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In the Mid-Session Reversal task (MSR), an animal chooses between two options, S1 and S2. Rewards follow S1 but not S2 from trials 1-40, and S2 but not S1 from trials 41-80. With pigeons, the psychometric function relating S1 choice proportion to trial number starts close to 1 and ends close to 0, with indifference (PSE) close to trial 40. Surprisingly, pigeons make anticipatory errors, choosing S2 before trial 41, and perseverative errors, choosing S1 after trial 40. These errors suggest that they use time into the session as the preference reversal cue. We tested this timing hypothesis with 10 Spotless starlings. After learning the MSR task with a T-s Inter-Trial Interval (ITI), they were exposed to either 2 T or T/2 ITIs during testing. Doubling the ITI should shift the psychometric function to the left and halve its PSE, whereas halving the ITI should shift the function to the right and double its PSE. When the starlings received one pellet per reward, the ITI manipulation was effective: The psychometric functions shifted in the direction and by the amount predicted by the timing hypothesis. However, non-temporal cues also influenced choice. published

In a variety of laboratory preparations, several animal species prefer signaled over unsignaled outcomes. Here we examine whether pigeons prefer options that signal the delay to impending reward over options that do not and how this preference changes with the ratio of the delays. We offered pigeons repeated choices between two alternatives leading to a short or a long delay to reward. For one alternative (informative), the short and long delays were reliably signaled by different stimuli (e.g. SS for short delays, SL for long delays). For the other (non-informative), the delays were not reliably signaled by the stimuli presented (S1 and S2). Across conditions, we varied the durations of the short and long delays while keeping the average delay to reward constant. Pigeons preferred the informative over the non-informative option and this preference became stronger as the ratio of the long to the short delay increased. A modified version of the Δ-Σ hypothesis (González et al., 2020a) incorporating a contrast-like process between the immediacies to reward signaled by each stimulus accounted well for our findings. Functionally, we argue that a preference for signaled delays hinges on the potential instrumental advantage typically conveyed by information.

Eckard and Lattal (2020) summarized the behavioristic view of hypothetical constructs and theories, and then, in a novel and timely manner, applied this view to a critique of internal clock models of temporal control. In our three-part commentary, we aim to contribute to the authors’ discussion by first expanding upon their view of the positive contributions afforded by constructs and theories. We then refine and question their view of the perils of reifying constructs and assigning them causal properties. Finally, we suggest to behavior analysts four rules of conduct for dealing with mediational theories: tolerate constructs proposed with sufficient reason; consider them seriously, both empirically and conceptually; develop alternative, behavior-analytic models with overlapping empirical domains; and contrast the various models. Through variation and selection, behavioral science will evolve.

Using signal detection theory, we investigated whether human participants represent time linearly or logarithmically in a bisection task. Participants saw a stimulus 1.0 to 1.5 s in duration, and then judged whether the stimulus duration was closer to 1.0 s or to 1.5 s, and how sure they were of their response. Whereas the mean of the subjective stimulus duration was a linear function of the objective stimulus duration, participants produced remarkably different psychophysical functions-linear for some participants, concave for others, and convex for still others. Hence, the appropriate question might not be whether humans encode time linearly or logarithmically, but for which participants and under which conditions is time encoded linearly, logarithmically, or even exponentially. (PsycINFO Database Record (c) 2018 APA, all rights reserved). 44

A meaningless symbol that repeatedly co-occurs with emotionally salient faces (US) can transform into a valenced symbol (CS). US-to-CS valence transformations have been observed for CS that have been directly (US→CS0) and indirectly (US→CS0→CS1→CS2) linked with face US. The structure of a US→CS0→CS1→CS2 series may be conceptualized in terms of “nodal distance,” where CS0, CS1, and CS2 are 0, 1, and 2 nodes from the US respectively. Increasing nodal distance between an evaluated CS and its linked US can reduce magnitude of observed CS valence transformations. We explored currently whether nodal distance can influence CS valence extinction, which describes reductions in CS valence following repeated exposures to CS without any accompanying US. In our study, faces with happy/neutral/sad expressions (US) were directly linked with nonsense words (US→CS0). The directly linked CS0 was concurrently linked with other words (CS0→CS1, CS1→CS2). Subjects evaluated all stimuli before and after conditioning, then continued to provide CS evaluations twice a week for 6 weeks. Bayesian factors provided credible evidence for the transformation and extinction of CS valences that were 0 and 1 nodes from US (all BF10’s > 100). The variability across post-conditioning CS evaluations provides indirect evidence for context-sensitive/propositional and structural/associative operations during CS evaluations.

Eckard and Lattal (2020) summarized the behavioristic view of hypothetical constructs and theories, and then, in a novel and timely manner, applied this view to a critique of internal clock models of temporal control. In our three-part commentary, we aim to contribute to the authors' discussion by first expanding upon their view of the positive contributions afforded by constructs and theories. We then refine and question their view of the perils of reifying constructs and assigning them causal properties. Finally, we suggest to behavior analysts four rules of conduct for dealing with mediational theories: tolerate constructs proposed with sufficient reason; consider them seriously, both empirically and conceptually; develop alternative, behavior-analytic models with overlapping empirical domains; and contrast the various models. Through variation and selection, behavioral science will evolve.

O presente documento constitui um relato teoricamente fundamentado da atividade desenvolvida enquanto estudante estagiário na Escola Secundária Inês de Castro, no âmbito da iniciação à prática profissional (Decreto-Lei n.º 79/2014 de 14 de maio). Este relatório consiste na descrição e análise dos acontecimentos importantes vividos ao longo deste ano letivo, responsáveis pela construção da identidade pessoal e profissional do futuro docente. N/A

Researchers have unraveled multiple cases in which behavior deviates from rationality principles. We propose that such deviations are valuable tools to understand the adaptive significance of the underpinning mechanisms. To illustrate, we discuss in detail an experimental protocol in which animals systematically incur substantial foraging losses by preferring a lean but informative option over a rich but non-informative one. To understand how adaptive mechanisms may fail to maximize food intake, we review a model inspired by optimal foraging principles that reconciles sub-optimal choice with the view that current behavioral mechanisms were pruned by the optimizing action of natural selection. To move beyond retrospective speculation, we then review critical tests of the model, regarding both its assumptions and its (sometimes counterintuitive) predictions, all of which have been upheld. The overall contention is that (a) known mechanisms can be used to develop better ultimate accounts and that (b) to understand why mechanisms that generate suboptimal behavior evolved, we need to consider their adaptive value in the animal’s characteristic ecology.

When offered a choice between 2 alternatives, animals sometimes prefer the option yielding less food. For instance, pigeons and starlings prefer an option that on 20% of the trials presents a stimulus always followed by food, and on the remaining 80% of the trials presents a stimulus never followed by food (the Informative Option), over an option that provides food on 50% of the trials regardless of the stimulus presented (the Noninformative Option). To explain this suboptimal behavior, it has been hypothesized that animals ignore (or do not engage with) the stimulus that is never followed by food in the Informative Option. To assess when pigeons attend to the stimulus usually not followed by food, we increased the probability of reinforcement, p, in the presence of that stimulus. Across 2 experiments, we found that the value of the Informative Option decreased with p. To account for the results, we added to the Reinforcement Rate Model (and also to the Hyperbolic Discounting Model) an engagement function, f(p), that specified the likelihood the animal attends to a stimulus followed by reward with probability p, and then derived the model predictions for 2 forms of f(p), a linear function, and an all-or-none threshold function. Both models predicted the observed findings with a linear engagement function: The higher the probability of reinforcement after a stimulus, the higher the probability of engaging the stimulus, and, surprisingly, the less the value of the option comprising the stimulus., This study was conducted at the Psychology Research Centre (UID/PSI/01662/2013) of the University of Minho, and supported by the Portuguese Foundation for Science and Technology (FCT) and the Portuguese Ministry of Science, Technology and Higher Education through national funds and cofinanced by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653). This work was also supported by an FCT Grant (PTDC/MHC-PCN/3540/2012) to AM. IF and CP were supported by FCT Doctoral Grants (SFRH/BD/77061/2011 and SFRH/BD/78566/2011, respectively).

In the natural environment, when an animal encounters a stimulus that signals the absence of food-a 'bad-news' stimulus-it will most likely redirect its search to another patch or prey. Because the animal does not pay the opportunity cost of waiting in the presence of a bad-news stimulus, the properties of the stimulus (e.g., its duration and probability) may have little impact in the evolution of the decision processes deployed in these circumstances. Hence, in the laboratory, when animals are forced to experience a bad-news stimulus they seem to ignore its duration, even though they pay the cost of waiting. Under certain circumstances, this insensitivity to the opportunity cost can lead to suboptimal preferences, such as a preference for an option yielding a low rather than a high rate of reinforcement. In 2 experiments, we tested Vasconcelos, Monteiro, and Kacelnik's (2015) assumption that, if given the opportunity, animals will escape the bad-news stimulus. To predict when an escape response should occur, we incorporated ideas from the prey choice model into Vasconcelos et al. (2015) model and made 2 novel predictions. Namely, both longer intertrial intervals and longer durations of signals predicting food or no food should lead to higher proportions of escape responses. The results of 2 experiments with pigeons supported these predictions., This study was conducted at the Psychology Research Centre, University of Minho, Portugal, and was supported by the Portuguese Foundation for Science and Technology (FCT) and the Portuguese Ministry of Education and Science through national funds cofinanced by FEDER under the PT2020 Partnership Agreement (UID/PSI/01662/2013). This work was also supported by FCT Grant PTDC/MHC-PCN/3540/2012 to Armando Machado. Ines Fortes was supported by FCT Doctoral Grant (SFRH/BD/77061/2011). We thank the members of the Animal Learning and Behavior Laboratory of University of Minho for their comments on a prior version of this paper., info:eu-repo/semantics/publishedVersion

The temporal bisection task, one of the most widely used to study time perception, has helped to understand the psychophysics of time and the mechanisms of timing across different species. We extended the temporal bisection task to dogs. Five dogs were reinforced for choosing a yellow but not a blue stimulus after a 1-s tone, and for choosing a blue but not a yellow stimulus after a 4-s tone. After they learned this conditional discrimination, the dogs chose between the blue and yellow stimuli after tones with intermediate durations (1.4, 2.0, and 2.8 s). The results showed that the proportion of “Long” choices increased monotonically with stimulus duration. Moreover, the point of subjective equality was slightly below the geometric mean of the trained tone durations. These psychophysical results are consistent with those obtained with other nonhuman species, and suggest that common mechanisms underlie timing across different mammals and birds., This research was part of the scientific program of Instituto Nacional de Ciência e Tecnologia Sobre Comportamento, Cognição e Ensino, with support from the Brazilian National Research Council (CNPq, Grant 465686/2014-1) and the São Paulo Research Foundation (Grant 2014/50909-8). Camila Domeniconi had a postdoctoral fellowship from the Foundation for Research Support in the State of São Paulo (FAPESP, 2009/ 18479-5). She has a research productivity fellowship bythe National Council for Scientific and Technological Development (CNPq, 301623/2012-0). Armando Machado was supported by grant PTDC/MHC-PCN/ 3540/ 2012 from the Portuguese Foundation for Science and Technology., info:eu-repo/semantics/publishedVersion

The ability to identify stimuli that signal important events is fundamental for an organism to adapt to its environment. In the present paper, we investigated how more than one stimulus could be used jointly to learn a temporal discrimination task. Ten pigeons were exposed to a symbolic matching-to-sample procedure with three durations as samples (2, 6, and 18 s of keylight) and two colors as comparisons (red and green hues). A 30-s intertrial interval (ITI), illuminated with a houselight, separated the trials. Both the houselight and the sample keylight could control responding, so two tests were run to assess how these stimuli influenced choice. In the no-sample test, the keylight was not presented; in the dark-ITI test, the houselight was not illuminated. Results suggest that both houselight and keylight controlled choice, and with the exception of one animal, the more a pigeon relied on one of these stimuli, the less it appeared to rely on the other., The present work was conducted at the Psychology Research Centre, University of Minho, and was supported by the Portuguese Foundation for Science and Technology (FCT) and the Portuguese Ministry of Education and Science through national funds and when applicable co-financed by FEDER under the PT2020 Partnership Agreement (UID/PSI/01662/2013). This work was also supported by FCT Doctoral Grants to Carlos Pinto (SFRH/BD/78566/2011) and Ines Fortes (SFRH/BD/77061/2011), and a FCT Grant (PTDC/MHC-PCN/3540/2012) to Armando Machado., info:eu-repo/semantics/publishedVersion

Responding by exclusion, one of the most robust phenomena in Experimental Psychology, describes a particular form of responding observed in symbolic, matching-to-sample tasks. Given two comparison stimuli, one experimentally defined and one experimentally undefined, the participant prefers the undefined comparison following an undefined sample. The goal of the present study was to determine whether responding by exclusion could be obtained using samples that varied along a single dimension. Using a double temporal bisection task, 10 university students learned to choose visual comparisons (colored circles) based on the duration of a tone. In tests of exclusion, sample stimuli with new durations were followed by comparison sets that included one previously trained, defined comparison (colored circle) and one previously untrained, undefined comparison (geometric shape). Participants preferred the defined comparisons following the defined samples and the undefined comparisons following the undefined samples, the choice pattern typical of responding by exclusion. The use of samples varying along a single dimension allows us to study the interaction between stimulus generalization gradients and exclusion in the control of conditional responding.

To test the Learning-to-Time model, six pigeons learned two temporal bisection tasks. In one task they learned to choose a Red key over a Green key following 2-s samples and the Green key over the Red key following 6-s samples; in another task, they learned to choose a Blue key over a Yellow key following 6-s samples and the Yellow key over the Blue key following 18-s samples. After each task was learned, temporal generalization gradients were obtained with samples ranging from 0.7 s to 51.4 s. Finally, preference for Green over Blue - the keys associated with the common 6-s duration, was determined as a function of sample duration. Two issues were examined, whether the preference for Green over Blue increased with sample duration, a transposition-like effect reported before, and whether the preference for Green over Blue could be predicted from the generalization gradients for Green and Blue previously obtained. Results showed that preference for Green over Blue increased with sample duration and that the general shape of the function could be predicted from the generalization gradients. The Learning-to-Time model accounted well for the major trends in the data., The authors thank Saulo Missiaggia Velasco for all the valuable help given during the data collection at the University of Sao Paulo. The authors also thank the students from the Animal Learning and Behavior laboratory of the University of Minho for their helpful comments on the paper. Ana Catarina Vieira de Castro was supported by a PhD fellowship and Armando Machado by a grant from the Portuguese Foundation for Science and Technology (FCT). Gerson Yukio Tomanari was supported by a grant from the Brazilian National Council for Science and Technology (CNPq)., info:eu-repo/semantics/publishedVersion

Inspired by Spence's seminal work on transposition, we propose a synthetic approach to understanding the temporal control of operant behavior. The approach takes as primitives the temporal generalization gradients obtained in prototypical concurrent and retrospective timing tasks and then combines them to synthetize more complex temporal performances. The approach is instantiated by the learning-to-time (LeT) model. The article is divided into three parts. In the first part, we review the basic findings concerning the generalization gradients observed in fixed-interval schedules, the peak procedure, and the temporal generalization procedure and then describe how LeT explains them. In the second part, we use LeT to derive by gradient combination the typical performances observed in mixed fixed-interval schedules, the free-operant psychophysical procedure, the temporal bisection task, and the double temporal bisection task. We also show how the model plays the role of a useful null hypothesis to examine whether temporal control in the bisection task is relative or absolute. In the third part, we identify a set of issues that must be solved to advance our understanding of temporal control, including the shape of the generalization gradients outside the range of trained stimulus durations, the nature of temporal memories, the influence of context on temporal learning, whether temporal control can be inhibitory, and whether temporal control is also relational. These issues attest to the heuristic value of a Spencean approach to temporal control., The authors MPC, AM, and MV were supported by grants SFRH/BD/73875/2010, PTDC/MHC-PCN/3540/2012, and IF/01624/2013/CP1158/CT0012, respectively, from the Portuguese Foundation for Science and Technology. This study was conducted at the Psychology Research Centre, University of Minho, and partially supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Education and Science through national funds and when applicable co-financed by FEDER under the PT2020 Partnership Agreement (UID/PSI/01662/2013)., info:eu-repo/semantics/publishedVersion

In temporal discriminations tasks, more than one stimulus may function as a time marker. We studied two of them in a matching-to-sample task, the sample keylight and the houselight that signaled the intertrial interval (ITI). One group of pigeons learned a symmetrical matching-to-sample task with two samples (2 s or 18 s of a center keylight) and two comparisons (red and green side keys), whereas another group of pigeons learned an asymmetrical matching-to-sample task with three samples (2 s, 6 s, and 18 s) and two comparisons (red and green). In the asymmetrical task, 6-s and 18-s samples shared the same comparison. In a subsequent retention test, both groups showed a preference for the comparison associated with the longer samples, a result consistent with the hypothesis that pigeons based their choices on the duration elapsed since the offset of the houselight (i.e., sample duration + retention interval). Results from two no-sample tests further corroborated the importance of the ITI illumination as a time marker: When the ITI was illuminated, the proportion of choices correlated positively with the retention interval; when the ITI was darkened, choices fell to random levels. However, the absolute value of choice proportions suggested that the sample stimulus was also a time marker. How multiple stimuli acquire control over behavior and how they combine remains to be worked out., This work was conducted at the Psychology Research Centre, University of Minho, and was supported by the Portuguese Foundation for Science and Technology (FCT) and the Portuguese Ministry of Education and Science through national funds, and when applicable co-financed by FEDER under the PT2020 Partnership Agreement (UID/PSI/01662/2013). This work was also supported by a FCT Doctoral Grant (SFRH/BD/78566/2011) to Carlos Pinto and a FCT Grant (PTDC/MHC-PCN/3540/2012) to Armando Machado., info:eu-repo/semantics/publishedVersion

Several studies have shown that, when offered a choice between an option followed by stimuli indicating whether or not reward is forthcoming and an option followed by noninformative stimuli, animals strongly prefer the former even when the latter is more profitable. Though this paradoxical preference appears to question the principles of optimal foraging theory, Vasconcelos, Monteiro, and Kacelnik (2015) proposed an optimality model that shows how such preference maximizes gains under certain conditions. In this paper, we tested the model's core assumption that a stimulus signaling the absence of food should not influence choice independently of its other properties, such as probability or duration. In 2 experiments, pigeons chose between 2 options: the "informative option" delivered food on 20% of the trials after a 10-s delay, signaled by a "good-news" stimulus, and delivered no food on the remaining 80% of the trials, signaled by a "bad-news" stimulus. The "noninformative option" delivered food after 10 s on 50% of the trials, regardless of the signal shown. In Experiment 1, the probability of the bad-news stimulus was manipulated from 0.80 to 1.00; in Experiment 2, the duration of the bad-news stimulus was increased every time pigeons preferred the informative option, reaching at least 200 s. Consistent with the model's predictions, pigeons clearly preferred the informative option even when the noninformative option delivered 9 (Experiment 1) and 35 (Experiment 2) times more food., This study was conducted at the Psychology Research Centre, University of Minho, Portugal, and was supported by the Portuguese Foundation for Science and Technology (FCT) and the Portuguese Ministry of Education and Science through national funds cofinanced by FEDER under the PT2020 Partnership Agreement (Grant UID/PSI/01662/2013). This work was also supported by FCT Grant PTDC/MHC-PCN/3540/2012 to Armando Machado. Ines Fortes and Marco Vasconcelos were supported by an FCT Doctoral Grant SFRH/BD/77061/2011 and an FCT Investigator Grant IF/01624/2013, respectively. We are grateful to Thomas Zentall and the members of the Animal Learning and Behavior Laboratory of University of Minho for their helpful comments on a prior version of this paper., info:eu-repo/semantics/publishedVersion

We examined whether temporal learning in a bisection task is absolute or relational. Eight pigeons learned to choose a red key after a t-seconds sample and a green key after a 3t-seconds sample. To determine whether they had learned a relative mapping (short -> Red, long -> Green) or an absolute mapping (t-seconds -> Red, 3t-seconds -> Green), the pigeons then learned a series of new discriminations in which either the relative or the absolute mapping was maintained. Results showed that the generalization gradient obtained at the end of a discrimination predicted the pattern of choices made during the first session of a new discrimination. Moreover, most acquisition curves and generalization gradients were consistent with the predictions of the learning-to-time model, a Spencean model that instantiates absolute learning with temporal generalization. In the bisection task, the basis of temporal discrimination seems to be absolute, not relational., The authors were supported by grants from the Portuguese Foundation for Science and Technology (FCT SFRH/BD/73875/2010 and PTDC/MHC-PCN/3540/2012). The study was conducted at the Psychology Research Centre of the University of Minho, and was partially supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Education and Science through national funds and cofinanced by FEDER under the PT2020 Partnership Agreement (UID/PSI/01662/2013). The authors thank Catarina Soares and Margarida Monteiro for helping with data collection, and the members of the Animal Learning and Behavior Lab for comments on a first version of the manuscript. Results reported here were presented at the 26th Meeting of the Spanish Society for Comparative Psychology, Braga, Portugal, and at the 2014 Annual Symposium of the Society for the Quantitative Analysis of Behavior, Chicago, Illinois., info:eu-repo/semantics/publishedVersion

[Excerpt] Barba’s (2012) article deftly weaves three main themes in one argument about operant variability. From general theoretical considerations on operant behavior (Catania, 1973), Barba derives methodological guidelines about response differentiation and applies them to the study of operant variability. In the process, he uncovers unnoticed features of operant variability research (e.g., Neuringer, 2002) and proposes interesting modifications and extensions of current experimental practices. Barba’s article calls for renewed attention to important issues, and we find merit in his proposal to evaluate operant variability by comparing response distributions along a common continuous measure. We are less convinced, however, by the conceptual underpinnings that he brings to the task. [...]

We investigated the effects of interdimensional discrimination training in the temporal generalization gradient. In a matching-to-sample task, pigeons learned to choose key S after a T-s houselight sample and key NS in the absence of the houselight sample. For one group of pigeons, T = 20 s; for another, T = 10 s. Subsequently, houselight duration was varied to obtain temporal generalization gradients. Results showed that (a) proportion S increased as houselight duration ranged from 0 s to T s and then remained high for houselight durations longer than T; (b) the gradients were well described by negative-exponential functions; (c) these non-flat gradients were present from the beginning of testing, and; (d) the average gradients obtained with T = 20 s and T = 10 s overlapped when plotted in relative time. We conclude that temporal control does not require explicit discrimination training along the temporal dimension, and that temporal generalization gradients obtained with an interdimensional protocol show the scalar property of timing. We discuss how these findings challenge current models of timing., This work was supported by Portuguese Foundation for Science and Technology (FCT) [Grant number PTDC/MHC-PCN/3540/2012] to Armando Machado. Ana Catarina Vieira de Castro was supported by an FCT doctoral grant [Grant number SFRH/BD/43398/2008], by ERDF funds through the Operational Competitiveness Programme-COMPETE, and by National Funds through FCT under project FCOMP-01-0124-FEDER-029527 [Grant number PTDC/MHC ETI/4890/2012], and Marco Vasconcelos was supported by an FCT Investigator Grant [Grant number IF/01624/2013]., info:eu-repo/semantics/publishedVersion

To better understand short-term memory for temporal intervals, we re-examined the choose-short effect. In Experiment 1, to contrast the predictions of two models of this effect, the subjective shortening and the coding models, pigeons were exposed to a delayed matching-to-sample task with three sample durations (2, 6 and 18 s) and retention intervals ranging from 0 to 20 s. Consistent with the coding model, the results suggested a sudden forgetting of memories for duration. In Experiment 2, to test the confusion hypothesis, the characteristics of the ITI and the retention interval differed. Contrary to the confusion hypothesis, a choose-short effect was obtained. In both experiments, a test with only two of the three comparison keys was performed. The results suggest three effects that may be controlling the birds’ responses: stimulus generalization when no retention interval is present; an increase in random responding at longer retention intervals; and, similarly, an increase in preference for the “short-sample” key at longer retention intervals.

Pigeons were trained on two temporal bisection tasks, which alternated every two sessions. In the first task, they learned to choose a red key after a 1-s signal and a green key after a 4-s signal; in the second task, they learned to choose a blue key after a 4-s signal and a yellow key after a 16-s signal. Then the pigeons were exposed to a series of test trials in order to contrast two timing models, Learning-to-Time (LeT) and Scalar Expectancy Theory (SET). The models made substantially different predictions particularly for the test trials in which the sample duration ranged from 1 s to 16 s and the choice keys were Green and Blue, the keys associated with the same 4-s samples: LeT predicted that preference for Green should increase with sample duration, a context effect, but SET predicted that preference for Green should not vary with sample duration. The results were consistent with LeT. The present study adds to the literature the finding that the context effect occurs even when the two basic discriminations are never combined in the same session., Research was supported by a grant from the Portuguese Foundation for Science and Technology (FCT) to Armando Machado. Joana Arantes was supported by a Ph.D. scholarship from the Portuguese Foundation for Science and Technology (FCT). We thank John Staddon, Randolph Grace, and Luı´s Oliveira for helpful comments on earlier versions of the paper, and Alexandra Lima for assistance with data collection., info:eu-repo/semantics/publishedVersion

The primary goal was to compare results from a free-operant procedure with pigeons [Machado, A., Guilhardi, P., 2000. Shifts in the psychometric function and their implications for models of timing. J. Exp. Anal. Behav. 74, 25-54, Experiment 2] with new results obtained with rats. The secondary goal was to compare the results of both experiments with dependent variables that were not used in the original publication. As in the original study with pigeons, rats were trained on a two-alternative free-operant psychophysical procedure in which left lever press responses were reinforced during the first and second quarters of a 60-s trial, and right lever press responses were reinforced during the third and fourth quarters of the trial. The quarters were reinforced according to four independent variable interval (VI) schedules of reinforcement. The VI duration was manipulated in each quarter, and shifts in the psychophysical functions that relate response rate with time since trial onset were measured. The results obtained with rats were consistent with those previously obtained with pigeons. In addition, results not originally reported were also consistent between rats and pigeons, and provided insights into the perception, memory, and decision processes in Scalar Expectancy Theory and Learning-to-Time Theory., Uminho - Universidade do Minho(MH44234), This research was supported by National Institute of Mental Health Grant MH44234 to Brown University, and by a Research Grant from the Portuguese Science and Technology Foundation to Universidade do Minho. The authors thank. An Le for conversion of the primary data into compatible format., info:eu-repo/semantics/publishedVersion

We examined whether temporal context influences how animals produce a time interval. Six pigeons pecked one key to start an interval and then another key to end the interval. Reinforcement followed whenever the interval duration fell within a range of values signaled by the keylight colors. During Phase 1, keylight colors S1 and L1, intermixed across trials, signaled the ranges (0.5-1.5 s) and (1.5- 4.5 s), respectively. During Phase 2, colors S2 and L2 signaled the ranges (1.5-4.5 s) and (4.5-13.5 s), respectively. We asked whether the intervals produced in the presence of L1 and S2, stimuli signalling the same range, varied with their temporal context, short in Phase 1, long in Phase 2. The results showed that a) the intervals produced in the presence of the different keylight colors accorded with the main properties of temporal differentiation, including Weber’s law, b) the L1 intervals had slightly higher means than the S2 intervals, a weak contrast effect, c) the L1 intervals also had higher variability than the S2 intervals. An extension of the learning-to-time model to temporal differentiation tasks reproduced some of the major features of the data but left unanswered how context might change the model parameters., MPC, AM, and MV benefited from grants from the Portuguese Foundation for Science and Technology (FCT SFRH/BD/73875/2010, PTDC/MHC-PCN/3540/2012, and IF/01624/2013/CP1158/CT0012, respectively). This study was conducted at the Psychology Research Centre, University of Minho, and partially supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Education and Science through national funds and when applicable co-financed by FEDER under the PT2020 Partnership Agreement (UID/PSI/01662/2013). The authors thank Catarina Soares, Margarida Monteiro, Francisca Cunha, Janete Silva, Lénia Amaral, Pilar Niño and Sofia Ribeiro for help collecting data., info:eu-repo/semantics/publishedVersion

To understand how effort, defined by number of responses required to obtain a reward, affects reward value, five pigeons were exposed to a self-control task. They chose between two alternatives, 2s of access to food after a delay of 10s, and 6s of access to food after an adjusting delay. The adjusting delay increased or decreased depending on the pigeons' choices. The delay at which the two alternatives were equally chosen defined the indifference point. To determine whether requiring responses during the delay led to more impulsive (smaller-sooner rewards) or self-controlled (larger-later rewards) choices, we varied the number of required pecks during the 10-s delay to the 2-s reinforcer, and assessed how the requirement affected the indifference points. In the High Rate Phase, they had to peck at least 10 times during the delay; in the Low Rate Phase, they could peck at most 5 times during the delay. For four pigeons the indifference point increased with the response requirement; for one pigeon it decreased. The results suggest that, in general, reward value varies inversely with effort., This work was supported by the Portuguese Foundation for Science and Technology (FCT) Grant (PTDC/MHC-PCN/3540/2012) to Armando Machado and Marco Vasconcelos. Ines Fortes and Marco Vasconcelos were supported by an FCT Doctoral Grant (SFRH/BD/77061/2011) and an FCT Investigator Grant (IF/01624/2013), respectively. We are grateful to the members of the Animal Learning and Behavior Laboratory of University of Minho for their helpful comments on a prior version of this paper., info:eu-repo/semantics/publishedVersion

To contrast the classic version of the Scalar Expectancy Theory (SET) with the Behavioral Economic Model (BEM), we examined the effects of trial frequency on human temporal judgments. Mathematical analysis showed that, in a temporal bisection task, SET predicts that participants should show almost exclusive preference for the response associated with the most frequent duration, whereas BEM predicts that, even though participants will be biased, they will still display temporal control. Participants learned to emit one response (R[S]) after a 1.0-s stimulus and another (R[L]) after a 1.5-s stimulus. Then the effects of varying the frequencies of the 1.0-s and 1.5-s stimuli were assessed. Results were more consistent with BEM than with SET. Overall, this research illustrates how the impact of non-temporal factors on temporal discrimination may help us to contrast associative models such as BEM with cognitive models such as SET. Deciding between these two classes of models has important implications regarding the relations between associative learning and timing. This article is part of a Special Issue entitled: Associative and Temporal Learning., This research was supported by NIH grant MH033881. Jeremie Jozefowiez and Armando Machado acknowledge support from the Fundacao para a Ciencia e a Tecnologia as well as from the European project COST ISCH Action TD0904 "Time in Mental activity" (www.timely-cost.eu). We would like to thank Sean Gannon and Sarah Sterling for help running parts of the experiments, Mario Laborda, Bridget McConnell, Gonzalo Miguez, and James Witnauer for comments on an earlier version of this manuscript. Correspondence concerning this article should be addressed to Jeremie Jozefowiez, laboratoire URECA, Universite Lille Nord de France, Campus de Lille3, Domaine Universitaire du Pont de Bois, BP 60149, 58653 Villeneuve d'Ascq Cedex, France. jeremie.jozefowiez@univ-lille3fr.

This study examined how two models of timing, scalar expectancy theory (SET) and learning to time (LeT), conceptualize the learning process in temporal tasks, and then reports two experiments to test these conceptualizations. Pigeons responded on a two-alternative free-operant psychophysical procedure in which responses on the left key were reinforceable during the first two, but not the last two, quarters of a 60-s trial, and responses on the right key were reinforceable during the last two, but not the first two, quarters of the trial. In Experiment 1 three groups of birds experienced a difference in reinforcement rates between the two keys only at the end segments of the trial (i.e., between the first and fourth quarters), only around the middle segments of the trial (i.e., between the second and third quarters), or in both end and middle segments. In Condition 1 the difference in reinforcement rate favored the left key; in Condition 2 it favored the right key. When the reinforcement rates differed in the end segments of the trial, the psychometric function--the proportion of right responses across the trial--did not shift across conditions; when it occurred around the middle of the trial or in both end and middle segments, the psychometric function shifted across conditions. Experiment 2 showed that the psychometric function shifts even when the overall reinforcement rate for the two keys is equal, provided the rates differ around the middle of the trial. This pattern of shifts of the psychometric function is inconsistent with SET. In contrast, LeT provided a good quantitative fit to the data.

This study examined how pigeons discriminate the relative frequencies of events when the events occur serially. In a discrete-trials procedure, 6 pigeons were shown one light nf times and then another nl times. Next, they received food for choosing the light that had occurred the least number of times during the sample. At issue were (a) how the discrimination was related to two variables, the difference between the frequencies of the two lights, D = nf - nl, and the total number of lights in the sample, T = nf + nl; and (b) whether a simple mathematical model of the discrimination process could account for the data. In contrast with models that assume that pigeons count the stimulus lights, engage in mental arithmetic on numerons, or remember the number of stimuli, the present model assumed only that the influence of a sample stimulus on choice increases linearly when the stimulus is presented, but decays exponentially when the stimulus is absent. The results showed that, overall, the pigeons discriminated the relative frequencies well. Their accuracy always increased with the absolute value of the difference D and, for D > 0, it decreased with T. Performance also showed clear recency, primacy, and contextual effects. The model accounted well for the major trends in the data.

Two theories of timing, scalar expectancy theory (SET) and learning to time (LeT), make substantially different assumptions about what animals learn in temporal tasks. In a test of these assumptions, pigeons learned two discriminations: On Type 1 trials, they learned to choose a red key after a 1-s signal and a green key after a 4-s signal; on Type 2 trials, they learned to choose a blue key after a 4-s signal and a yellow key after a 16-s signal. Then, two psychometric functions were obtained by presenting them with intermediate durations (1 to 4 s and 4 to 16 s). The two functions did not superpose, and most bisection points were not at the geometric mean of the training stimuli (contra SET); for most birds, the function for Type 2 trials was to the left of the function for Type 1 trials (contra LeT). Finally, the birds were exposed to signals ranging from 1 to 16 s and given a choice between novel key combinations (e.g., red vs. blue). The results with the novel key combinations were always closer to LeT's than to SET's predictions. Observations of the birds' behavior also suggest that, more than being a mere expression of an internal clock, behavior constitutes the clock.

Overshadowed by more popular disciplines, the study of learning seems to have lost its prominent place in the undergraduate psychology curriculum. In the first part of this essay, we argue that one reason for this state of affairs is the current content of psychology of learning courses, namely, its disproportionate emphasis on facts, procedures, and everyday examples at the expense of functional and conceptual investigations. In the second part of the essay, we outline an alternative approach to the teaching of learning, one that emphasizes basic contents such as the conceptualization of learning as a biological adaptation or the study of temporal regulation, critical methodological issues such as the logic of experimental designs or the difficulties of measuring behavior, and broad epistemological problems such as the role of hypothetical constructs, the advantages of quantitative reasoning, or the origins of knowledge and its integration. By using learning as a means towards more fundamental ends, the splendor of the discipline and its prominent place in the undergraduate curriculum may be restored.

Three experiments compared the amounts of behavioral variability generated with two reinforcement rules. In Experiments 1 and 2 pigeons received food whenever they generated a sequence of eight pecks, distributed over two keys, provided that the sequence contained a certain number of change-overs between the keys. Although no variability was required-the birds could obtain all reinforcers by repeating the same sequence-the pigeons emitted a large number of different sequences. In Experiment 3 pigeons received food whenever they generated a sequence that had not occurred during the last 25 trials. After prolonged training, the birds showed more sequence variability than in the first two experiments. The analysis of the internal structure of the response sequences revealed that, in general, (a) the location of the first peck was highly stereotyped; (b) as the trial advanced, the probability of switching to the initially preferred key decreased whereas the probability of switching to the other key increased; and (c) a first-order Markov chain model with transition probabilities given by a logistic function accounted well for the internal structure of the birds' response sequences. These findings suggest that, to a large extent, the variability of response sequences is an indirect effect of adjustments in changeover frequency.

Models of timing differ on two fundamental issues, the form of the representation and the content of learning. First, regarding the representation of time some models assume a linear encoding, others a logarithmic encoding. Second, regarding the content of learning cognitive models assume that the animal learns explicit representations of the intervals relevant to the task and that their behavior is based on a comparison of those representations, whereas associative models assume that the animal learns associations between its representations of time and responding, which then drive performance. In this paper, we show that some key empirical findings (timescale invariant psychometric curves, bisection point at the geometric mean of the trained durations in the bisection procedure, and location of the indifference point in the time-left procedure) seem to make these two issues interdependent. That is, cognitive models seem to entail a linear representation of time, and at least a certain class of associative models seem to entail a log representation of time. These interdependencies suggest new ways to compare and contrast timing models., Jeremie Jozefowiez and Armando Machado acknowledge support from the Fundacao para a Ciencia e a Tecnologia as well as from the European project COST ISCH Action TD0904 "Time in Mental activity" (www.timely-cost.eu)., info:eu-repo/semantics/publishedVersion

In two experiments, we investigated emergent conditional relations in pigeons using a symbolic matching-to-sample task with temporal stimuli as the samples and hues as the comparisons. Both experiments comprised three phases. In Phase I, pigeons learned to choose a red keylight (R) but not a green keylight (G) after a 1-s signal. They also learned to choose G but not R after a 4-s signal. In Phase II, correct responding consisted of choosing a blue keylight (B) after a 4-s signal and a yellow keylight (Y) after a 16-s signal. Comparisons G and B were both related to the same 4-s sample, whereas comparisons R and Y had no common sample. In Phase III, R and G were presented as samples, and B and Y were presented as the comparisons. The choice of B was correct following G, and the choice of Y was correct following R. If a relation between comparisons that shared a common sample were to emerge, then responding to B given G would be more likely than responding to Y given R. The results were generally consistent with this prediction, suggesting, for the first time in pigeons, the emergence of novel relations that involve temporal stimuli as nodal samples., This research was supported by doctoral grants to E.M.H. (FAPESP 60678-4/05 and CAPES 0103/08 0) and S.M.V. (CNPq 142544/2005-1 and CAPES 4457 07 2). G.Y.T. and D.G.d.S. were supported by a research productivity fellowship from The National Council for Scientific and Technological Development (CNPq, Brazil). A.D.M. was funded by the Portuguese Foundation for Science and Technology (FCT). All of the Brazilian authors are currently affiliated with the National Institute of Science and Technology on Behavior, Cognition and Teaching, supported by FAPESP (Grant No. 08/57705-8) and CNPq (Grant No. 573972/2008-7). The data were collected in the Animal Learning and Behavior Laboratory, University of Minho, Portugal, and were presented at the 36th Annual Meeting of the Brazilian Society of Psychology (SBP), Goiania, Brazil, in October 2009. E.M.H. is currently a college professor at the Universidade Federal de Minas Gerais., info:eu-repo/semantics/publishedVersion

The experiment examined how pigeons differentiate response patterns along the dimension of number. Seven pigeons received food after pecking the left key at least N times and then switching to the right key (Mechner’s Fixed Consecutive Number schedule). Parameter N was set according to a percentile schedule, which is a form of automatic shaping. Our aim was twofold: on the empirical side to determine how run length on the left key would evolve under this shaping procedure and how it would change during a subsequent extinction phase; and on the theoretical side to compare the data with the predictions of a theoretical model of response differentiation. Results showed that during shaping, run length on the left key increased and then, for some pigeons, it stabilized, whereas for others pigeons it remained variable. Some pigeons ceased to respond when average run length reached a highvalue. There were substantial within-session trends in run length. In extinction, before the pigeons ceased to respond altogether, they emitted the same distribution of run lengths as during the last sessions of shaping with the exception, in some birds, of a large number of runs of length zero. These results are interpreted at the light of the theoretical model of numerosity differentiation.Keywords: Mathematical Model, Response Numerosity, Percentile Schedule, Shaping, Pigeon, O presente estudo analisa a diferenciação numérica de padrões de resposta. Em uma caixa de Skinner com duas teclas, sete pombos receberam comida após bicarem pelo menos N vezes na tecla esquerda e depois uma vez na tecla direita (programa “Fixed Consecutive Number” de Mechner). Em cada ensaio, o parâmetro N era ajustado por um programa de reforço percentil (uma forma de shaping automático). O estudo teve dois objetivos. Primeiro, determinar como é que varia o tamanho das corridas na tecla da esquerda durante o procedimento de modelagem (shaping) e durante uma fase de extinção que se seguiu. Segundo, comparar os dados obtidos com as previsões de um modelo teórico de diferenciação da resposta. Os resultados mostraram que, durante a modelagem, o tamanho das corridas na tecla esquerda aumentou e depois, para alguns pombos, estabilizou, enquanto para outros pombos permaneceu variável. Alguns pombos pararam de responder quando o tamanho médio da corrida atingiu valores elevados. Observaram-se ainda variações sistemáticas nos tamanhos das corridas no interior de cada sessão como, por exemplo, o aumento do tamanho da corrida ao longo da sessão. Durante a fase de extinção os pombos produziram distribuições de tamanhos de corrida semelhantes às distribuições produzidas durante as últimas sessões de modelagem com exceção, em alguns sujeitos, do elevado número de corridas de tamanho zero. Estes resultados são interpretados à luz do modelo teórico de diferenciação numérica das respostas. Palavras-chave: Modelo matemático, numerosidade, esquema percentil, modelagem, pombo

In a temporal double bisection task, animals learn two discriminations. In the presence of Red and Green keys, responses to Red are reinforced after 1-s samples and responses to Green are reinforced after 4-s samples; in the presence of Blue and Yellow keys, responses to Blue are reinforced after 4-s samples and responses to Yellow are reinforced after 16-s samples. Subsequently, given a choice between Green and Blue, the probability of choosing Green increases with the sample duration_the context effect. In the present study we asked whether this effect could be predicted from the stimulus generalization gradients induced by the two basic discriminations. Six pigeons learned to peck Green following 4-s samples (S+) but not following 1-s samples (S2) and to peck Red following 4-s samples (S+) but not following 16-s samples (S2). Temporal generalization gradients for Green and Red were then obtained. Finally, the pigeons were given a choice between Green and Red following sample durations ranging from 1 to 16 s. Results showed that a) the two generalization gradients had the minimum at the S2 duration, an intermediate value between the S2 and the S+ durations, and the maximum at the S+ as well as more extreme durations; b) on choice trials, preference for Green over Red increased with sample duration, the context effect; and c) the two generalization gradients predicted the average context effect well. The Learning-to-Time model accounts for the major trends in the data., The authors thank the students from the Animal Learning and Behavior laboratory of the University of Minho for their helpful comments on the paper. Ana Catarina Vieira de Castro was supported by a PhD fellowship and Armando Machado by a grant from the Portuguese Foundation for Science and Technology (FCT).

In a discrete-trials procedure, a frequency-dependent schedule shaped left-right choice proportion toward various equilibrium values between 0 and 1. At issue was (1) whether pigeons match when the overall reinforcement probabilities for two responses depend inversely on their recent frequency, and (2) how pigeons meet the schedule constraint in terms of local responding. That is, do they respond quasi-randomly (Bernoulli mode), or do they learn the stable pattern of the schedule (stable-pattern mode)? Molar choice behavior always tracked the equilibrium solution of the schedule, but the molecular response patterns varied substantially. Markov chains applied to the data revealed that responding was generally intermediate between the memoryless Bernoulli mode, and the perfect memory stable-pattern mode. The polymorphism of molecular patterns, despite molar regularities in behavior, suggests that (1) in order to engender the Bernoulli or stable-pattern modes, the reinforcement rule must strongly discourage competing response patterns (e.g., perseveration), and (2) under frequency-dependent schedules, molar matching is apparently not the outcome of momentary maximizing.

When subjects learn to associate two sample durations with two comparison keys, do they learn to associate the keys with the short and long samples (relational hypothesis), or with the specific sample durations (absolute hypothesis)? We exposed 16 pigeons to an ABA design in which phases A and B corresponded to tasks using samples of 1s and 4 s, or 4 s and 16 s. Across phases, we varied the mapping between the samples and the keys. For group Relative, short and long samples were always associated with the same keys (e.g., Phase A: ‘1s--> Left, 4 s--> Right’; Phase B: ‘4 s--> Left, 16 s--> Right’); for group Absolute, the 4-s sample was associated always with the same key (e.g., Phase A: ‘1s--> Left, 4 s--> Right’; Phase B: ’16 s--> Left, 4 s--> Right”). If temporal control is relational, group Relative should learn the new task faster than group Absolute, but if temporal control is absolute, the opposite should occur. We compared the results with the predictions of the Learning-to-Time (LeT) model, which accounts for temporal discrimination in terms of absolute stimulus control and stimulus generalization. The acquisition curves of the two groups were generally consistent with LeT and therefore more consistent with the absolute than the relative hypothesis., The authors thank the members of the Animal Learning and Behavior Lab of the University of Minho for their helpful comments. The work was supported by grants to the two authors from the Portuguese Foundation for Science and Technology (FCT).

In the present study we extended errorless learning to a conditional temporal discrimination. Pigeons’ responses to a left–red key after a 2-s sample and to a right–green key after a 10-s sample were reinforced. There were two groups: One learned the discrimination through trial and error and the other through an errorless learning procedure. Then, both groups were presented with three types of tests. First, they were exposed to intermediate durations between 2 s and 10 s, and given a choice between both keys (stimulus generalization test). Second, a delay from 1 s to 16 s was included between the offset of the sample and the onset of the choice keys (delay test). Finally, pigeons learned a new discrimination in which the stimuli were switched (reversal test). Results showed that pigeons from the Errorless group made significantly fewer errors than those in the Trial-and-Error group. Both groups performed similarly during the stimulus generalization test and the reversal test, but results of the delay test suggested that, on long stimulus trials, responding in the errorless training group was less disrupted by delays., This research was presented in part at the 33rd Annual Convention of the Association of Behavioral Analysis (ABA) in San Diego, California. The authors were supported by the Portuguese Foundation for Science and Technology (FT). The authors thank Herbert S. Terrace for his valuable thoughts at the 31st Annual Meeting of the Society for the Quantitative Analyses of Behavior (SQAB) about this research.

The present experiment investigated whether pigeons can show associative symmetry on a two-alternative matching to-sample procedure The procedure consisted of a within subject sequence of training and testing with reinforcement and It provided (a) exemplars of symmetrical responding and (b) all prerequisite discriminations among test samples and comparisons After pigeons had learned two arbitrary matching tasks (A B and C D) they were given a reinforced symmetry test for half of the baseline relations (B1-A1 and D1-C1) To control for the effects of reinforcement during testing two novel nonsymmetrical responses were concurrently reinforced using the other baseline stimuli (D2-A2 and B2-C2) Pigeons matched at chance on both types of relations thus indicating no evidence for symmetry These symmetrical and nonsymmetrical relations were then directly trained in order to provide exemplars of symmetry and all prerequisite discriminations for a second test The symmetrical test relations were now B2-A2 and D2-C2 and the nonsymmetrical relations were D1-A1 and B1-C1 On this test 1 pigeon showed clear evidence of symmetry 2 pigeons showed weak evidence and 1 pigeon showed no evidence The previous training of all prerequisite discriminations among stimuli and the within subject control for testing with reinforcement seem to have set favorable conditions for the emergence of symmetry in nonhumans However the variability across subjects shows that methodological variables still remain to be controlled, This research was supported by Doctoral Grant (CNPq 142544/2005-1) and Doctoral Sandwich Grant (CAPES 4457-07 2) to Saulo M Velasco Doctoral Grant (FAPESP 60678-4/05) and Doctoral Sandwich Grant (CAPES 0103/08-0) to Edson M Huziwara Researcher Grant (CNPq 302640/2007-0) and Research Support (CNPq 471953/2004-0) to Gerson Y Tomanari Armando Machado was funded by the Portuguese Foundation for Science and Technology (FCT), info:eu-repo/semantics/publishedVersion

In the time-left procedure, a task used to study prospective timing, animals choose between two stimuli that signal different delays to reinforcement. Trials begin with one stimulus signaling C seconds to reinforcement and, at different moments since its onset, another stimulus, signaling S seconds to reinforcement, with C>S, is introduced. Optimal performance consists in choosing the stimulus signaling the shorter time to reinforcement. Animals have been found to perform in this optimal way. However, this procedure is complex and variables other than time may be responsible for the results. In two experiments with pigeons we sought to improve the time-left procedure to better isolate the effect of time in the animals' behavior. We attempted to control for two confounding variables, the asymmetry in the time markers from training to testing and the cost of switching between the two response alternatives. We conclude that in the time-left task pigeons seem indeed to regulate their behavior based on time because, with our improved procedure, they still chose the stimulus associated with the shorter time to food. However, our version of the procedure created new interpretative difficulties, strengthening the idea that the time-left procedure may be too complex to study timing., The authors would like to thank Luis Oliveira for his help in developing the present study and Jeremie Jozefowiez for comments on an earlier version of the manuscript. Work supported by the Portuguese Foundation for Science and Technology (FCT) grants SFRH/BD/43398/2008 and PTDC/PSI/65678/2006., info:eu-repo/semantics/publishedVersion

O objetivo deste modelo é apresentar um planejamento financeiro de execução de obras da construção civil, usando apenas recursos próprios, sem comprometer o prazo de entrega, nem a imagem da construtora, com otimização utilizando o simplex. Um melhor resultado para a filial de Recife é perseguido exaustivamente. A realidade do mercado imobiliário da cidade de Recife e as práticas existentes num grupo construtor são descritas e servem de pano para a problemática do planejamento e a solução adotada, a partir da sustentação teórica. Os resultados alcançados são analisados de forma aberta. As novas realidades, oriundas da implantação do planejamento, bem como os melhoramentos no modelo que se fizeram necessários são apresentados e analisados, na sua ordem cronológica. Além de tudo, é um registro interessante de como uma empresa preocupada na melhoria de sua gestão, aprende com seus erros e se adapta a novas realidades, sem perder seu foco

In the last decades, researchers have proposed a large number of theoretical models of timing. These models make different assumptions concerning how animals learn to time events and how such learning is represented in memory. However, few studies have examined these different assumptions either empirically or conceptually. For knowledge to accumulate, variation in theoretical models must be accompanied by selection of models and model ideas. To that end, we review two timing models, Scalar Expectancy Theory (SET), the dominant model in the Field, and the Learning-to-Time (LeT) model, one of the few models dealing explicitly with learning. In the first part of this article, we describe how each model works in prototypical concurrent and retrospective timing tasks, identify their structural similarities, and classify their differences concerning temporal learning and memory. In the Second part, we review a series of studies that examined these differences and conclude that both the memory structure postulated by SET and the state dynamics postulated by LeT are probably incorrect. In the third part, we propose a hybrid model that may improve on its parents. The hybrid model accounts for the typical findings in fixed-interval schedules, the peak procedure, mixed fixed interval schedules, simple and double temporal bisection, and temporal generalization tasks. In the fourth and last part, we identify seven challenges that any timing model trust meet., Fundação para a Ciência e a Tecnologia (FCT)

We examined if the representation of time intervals in a temporal discrimination task is based not only on their absolute but also on their relative durations. Six pigeons learned two temporal discriminations. In the first, red and green choices were correct following 2-s and 8-s samples, respectively. In the second, vertical and horizontal bar choices were correct following 4-s and 16-s samples, respectively. In a previous study [Zentall, T.R., Weaver, J.E., Clement, T.S., 2004. Pigeons group time intervals according to their relative duration. Psychon. Bull. Rev. 11, 113-117.]. tests with 4-s samples and red/green comparisons revealed a bias for red, whereas tests with 8-s samples with vertical/horizontal comparisons revealed a bias for horizontal. These results were interpreted in terms of relative encoding of sample durations. We attempted to replicate this finding but instead of testing with only 4-s or 8-s samples, we tested with several other sample durations to obtain a psychometric function. Results were inconsistent with the relative encoding hypothesis., Part of the work reported here was included in a Masters thesis submitted by the first author to the University of Minho, Portugal. Research supported by a grant from the Portuguese Foundation for Science and Technology (FCT) to the second author., info:eu-repo/semantics/publishedVersion