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We studied implicit relational learning by embedding contextual relational information into a multiple-object tracking task. In two experiments, participants were instructed to track two or four out of eight moving objects and report at the end of the trial whether a single cued object was among those they tracked (yes/no task). The stimulus display also contained two background strips of different width. In the informative condition, the location of the cued object predicted the correct choice: If the answer was "yes", then the cued object was always located next to the narrower strip; otherwise, it was always located next to the wider strip (or vice versa). In the random condition, the location of the object did not predict the correct choice. Participants in the informative condition consistently displayed lower tracking accuracy than in the random condition, possibly due to attentional demands introduced by implicit relational task. At the same time, participants in the informative condition demonstrated no awareness of the task structure; instead, their reports were consistent with the attempts to track moving objects. Our task can provide a suitable model for studying implicit relational learning in adult participants that is essential for establishing generality of factors affecting relational learning. [ABSTRACT FROM AUTHOR]

The effects of reinforcement value and social control on instruction following under a negative-reinforcement (escape) schedule were studied. Initially, responding produced timeouts from pressing a force cell under a low and a high force requirement on a fixed-ratio 1 schedule of reinforcement. Next, participants were reexposed to the low and high force requirements, but were instructed that the experimenter expected them to decrease the number of timeouts relative to the previous exposures to the procedure. Even though following the instruction led to a decrease in number of timeouts and to an increase in effort (i.e., was non-efficient), instruction following occurred consistently for each participant and was modulated by reinforcement value. That is, the decrease in the number of timeouts (i.e., instruction following) was lower under the high force requirement than under the low force requirement. These results replicate and extend previous findings that instructions interact with social and nonsocial contingencies in controlling human behavior. [ABSTRACT FROM AUTHOR]

The present study demonstrates the contribution of spatial contiguity in the formation of associations between two neutral stimuli. Using human participants, we used visual conditioned stimuli (CSs) in a sensory preconditioning design in which simultaneous CS2-CS1 pairings and CS4-CS3 pairings were interspersed during Phase 1, followed by sequential CS1-US+ (i.e., CS1-pleasant US) and CS3-US- − (i.e., CS3-unpleasant US) pairings during Phase 2. The conditioned response was a shift in the gaze of the participants to the location where the US+ (i.e., short video clip) appeared. Distances between CS2 and CS1 and between CS4 and CS3 were manipulated. Our results showed a greater response to CS2 when the Phase 1 stimuli were adjacent rather than separated by 100 pixels. Implications for the role of spatial contiguity in associative learning are discussed. [ABSTRACT FROM AUTHOR]

Previously reinforced responses can reappear when reinforcement is withdrawn from current responding. This is known as resurgence. Although resurgence of response topography, spacing, and patterns over time has been demonstrated, there is no evidence of resurgence of response duration. This experiment explored resurgence of response duration in humans. In Phase 1 a multiple schedule of reinforcement with two components was used. In each component a chained variable-interval 30 s, variable-ratio 3 schedule was implemented. In the terminal link of the chained schedule, response durations between 0.1 and 0.5 s were reinforced during one component, and between 2 and 8 s in the other component. In Phase 2, response requirement during the terminal link of the chained schedule was inverted between components relative to Phase 1. In Phase 3 the chained schedule was changed to a variable-interval 30-s, extinction 30 s. Resurgence of the durations trained during Phase 1 was observed. It was concluded that duration is a response dimension that reappears during extinction. [ABSTRACT FROM AUTHOR]

The effects of instructions on the sensitivity of negatively reinforced (escape) behavior to extinction were studied. Initially, responding produced timeouts from pressing a force cell on a variable-ratio (VR) schedule, which was then discontinued (extinction). Based on extinction data, participants were distributed into two groups. Participants in the Extinction Group (for which response rates were low in extinction) were instructed that the experimenter expected them to continue responding in extinction after a second exposure to the VR schedule. Participants in the Persistence group (for which response rates were high in extinction) were instructed that the experimenter expected them to stop responding in extinction. Relative to the condition in which instructions were absent, extinction-response rates increased and decreased, respectively, for participants in the Persistence and Extinction groups. These results replicate and extend to negatively reinforced responding previous findings that showed behavioral control by instructions formulated as explicit experimenter demands or expectations. [ABSTRACT FROM AUTHOR]

The relation between persistence, as measured by resistance to change, and resurgence has been examined with nonhuman animals but not systematically with humans. The present study examined persistence and resurgence with undergraduate students engaging in a computer task for points exchangeable for money. In Phase 1, a target response was maintained on a multiple variable-interval (VI) 15-s (Rich) VI 60-s (Lean) schedule of reinforcement. In Phase 2, the target response was extinguished while an alternative response was reinforced at equal rates in both schedule components. In Phase 3, the target and the alternative responses were extinguished. In an additional test of persistence (Phase 4), target responding was reestablished as in Phase 1 and then disrupted by access to videos in both schedule components. In Phases 2 and 4, target responding was more persistent in the Rich than in the Lean component. Also, resurgence generally was greater in the Rich than in the Lean component in Phase 3. The present findings with humans extend the generality of those obtained with nonhuman animals showing that higher reinforcement rates produce both greater persistence and resurgence, and suggest that common processes underlie response persistence and relapse. [ABSTRACT FROM AUTHOR]

Three pigeons were trained to remember arrays of 2–6 colored squares and detect which of two squares had changed color to test their visual short-term memory. Procedures (e.g., stimuli, displays, viewing times, delays) were similar to those used to test monkeys and humans. Following extensive training, pigeons performed slightly better than similarly trained monkeys, but both animal species were considerably less accurate than humans with the same array sizes (2, 4 and 6 items). Pigeons and monkeys showed calculated memory capacities of one item or less, whereas humans showed a memory capacity of 2.5 items. Despite the differences in calculated memory capacities, the pigeons’ memory results, like those from monkeys and humans, were all well characterized by an inverse power-law function fit to d ’ values for the five display sizes. This characterization provides a simple, straightforward summary of the fundamental processing of visual short-term memory (how visual short-term memory declines with memory load) that emphasizes species similarities based upon similar functional relationships. By closely matching pigeon testing parameters to those of monkeys and humans, these similar functional relationships suggest similar underlying processes of visual short-term memory in pigeons, monkeys and humans. [ABSTRACT FROM AUTHOR]

The generalized matching equation provides a good description of response allocation in concurrent schedules of positive reinforcement in nonhumans as well as in humans. The present experiment was conducted to further investigate the allocation of responding under concurrent schedules of negative reinforcement (i.e., timeouts from pressing a force cell) in humans. Each of three participants was exposed to different reinforcement ratios (9:1, 1:1 and 1:9) in the terminal links of a concurrent-chains schedule of negative reinforcement. The allocation of responding under this schedule was well described by the generalized matching equation, for each participant. These results replicate previous findings obtained with nonhumans and humans under concurrent schedules of positive reinforcement. In addition, they extend the results reported by Alessandri and Rivière (2013) showing that human behavior maintained by timeouts from an effortful response is sensitive to changes in relative reinforcement ratios as well as relative delays of reinforcement. [ABSTRACT FROM AUTHOR]

Freezing-like topographies of behavior are elicited in conditioned suppression tasks whereby appetitive behavior is reduced by presentations of an aversively conditioned threat cue relative to a safety cue. Conditioned suppression of operant behavior by a Pavlovian threat cue is an established laboratory model of quantifying the response impairment seen in anxiety disorders. Little is known however about how different response topographies indicative of conditioned suppression are elicited in humans. Here, we refined a novel virtual reality (VR) paradigm in which presentations of a threat cue of unpredictable duration occurred while participants performed an operant response of shooting and destroying boxes searching for hidden gold. The VR paradigm detected significant suppression of response topographies (shots, hits and breaks) for a Pavlovian threat cue relative to a safety cue and novel cue presentations. Implications of the present findings for translational research on appetitive and aversive conflict in anxiety disorders are discussed. [ABSTRACT FROM AUTHOR]

Resurgence occurs when a previously reinforced and then extinguished target response increases due to a worsening of reinforcement conditions for an alternative response. We conducted four crowdsourcing experiments to evaluate effects of alternative-reinforcer rate and magnitude on resurgence with humans. Contingent on an alternative response, we manipulated across groups either the rate of point delivery (Experiment 1) or number of points delivered per reinforcer (Experiments 2–3). Experiment 4 arranged combinations of high- or low-rate and high- or low-magnitude alternative reinforcement across four groups. When extinguishing alternative responding across experiments, we observed resurgence of target responding with relatively high rates of alternative reinforcement but differences in reinforcer magnitude did not influence resurgence. A quantitative model based on the concatenated matching law, Resurgence as Choice in Context (RaC2), provided a poor fit to the data, generally underpredicted target responding, and could not account for data from control groups experiencing extinction of target responding in the absence of alternative reinforcement. We then fit a modified version of RaC2 borrowing an assumption from theories of choice that suggest some proportion of reinforcers are misallocated between responses – this modified version of RaC2 provided a better account of these findings. • Examined effects of reinforcer rate and magnitude on resurgence through crowdsourcing. • In four experiments, greater reinforcer rates but not magnitudes increased resurgence. • We fit a quantitative model based on matching, Resurgence as Choice in Context (RaC2). • RaC2 fits improved when assuming reinforcers are misallocated between responses. • Misallocation also allowed RaC2 to be fit for the first time to simple extinction data. [ABSTRACT FROM AUTHOR]

Resurgence occurs when a worsening of conditions for an alternative response (e.g., extinction) increases a previously reinforced and subsequently extinguished target response. In contrast, renewal is an increase in a response previously eliminated by extinction following a contextual change. Moreover, arranging contextual changes during resurgence tests has enhanced relapse compared with the absence of contextual changes. Several laboratory studies evaluating resurgence in humans have included interruptions of operant tasks by presenting instructions or "blackouts" immediately prior to phase changes in which reinforcement contingencies change. Such interruptions could enhance relapse during testing similarly to changes in contextual stimuli. We tested this possibility in the present study with human participants recruited via Amazon Mechanical Turk by interrupting the task across groups with 1-s blackouts every 12 s, 60 s, between phases, or by arranging no blackouts in a control group. We found that blackouts prior to phase changes increased resurgence effects relative to no blackouts, suggesting that blackouts between phases are a type of contextual manipulation serving to increase the salience of contingency changes. • Evaluated whether blackouts serve as contextual stimuli to enhance resurgence. • Brief blackouts between phase changes increased resurgence compared to no blackouts. • Between-phase blackouts could increase salience of contingency changes. [ABSTRACT FROM AUTHOR]

Laboratory models of relapse provide methods for evaluating challenges to behavioral treatments with differential reinforcement of an alternative response (DRA). Resurgence occurs with the worsening of conditions of reinforcement for appropriate behavior and renewal occurs when transitioning out of a treatment context. Across five experiments, participants recruited via online crowdsourcing pressed onscreen buttons to earn points exchangeable for money and contexts sometimes changed through changes in the background image. Returning to the training context (ABA, Experiment 1) and transitioning to a novel context (ABC, Experiment 2) produced greater resurgence when removing alternative reinforcement in comparison with remaining in the treatment context (ABB). In contrast, we observed little difference in resurgence among AAA, ABB, and AAC context manipulations (Experiment 3) and ABA, ABC, and AAC context manipulations (Experiment 4). In Experiment 5, we evaluated relative contributions of the presence versus absence of context changes (ABA vs. ABB) in combination with or without the removal of alternative reinforcement. Both changing context and removing alternative reinforcement increased responding in isolation and the combination produced greater-than-additive effects. Overall, the present findings demonstrate a consistent effect of removing alternative reinforcement on relapse that, under certain conditions, can be enhanced by context change. • We evaluated effects of context changes on resurgence of a button press with humans. • ABA and ABC context changes enhanced resurgence relative to ABB context changes. • Similar levels of resurgence occurred with AAA, ABB, and AAC context changes. • Similar levels of resurgence occurred with ABA, ABC, and AAC context changes. • Context changes and extinction produced greater-than-additive response increases. [ABSTRACT FROM AUTHOR]

Highlights: [•] Substance-dependent subjects discount delayed rewards at higher rates than controls. [•] Cocaine- and nicotine-dependents discount more than those dependent on nicotine only. [•] Cocaine- and nicotine-dependents do not discount more than those dependent on cocaine only. [•] Delay discounting rates differ depending on the type of SUD. [•] No cumulative effect of number of SUD on delay discounting was observed. [Copyright &y& Elsevier]

Highlights: [•] Participants played a Paper Scissors Rock game against a computer or a fictitious human opponent. [•] Sensitivity to the relative reinforcer rate was higher for those in the “computer” condition than the “player” condition. [•] Perceived opponent type can alter the effect of reinforcer contingencies on human choice behaviour. [•] The generalised matching law was a good descriptor of three-alternative human choice behaviour. [Copyright &y& Elsevier]

Highlights: [•] A new procedure to study human operant conditioning is described using a rest force period as reinforcer when high force was required. [•] Experiment 1 reports evidence that the rest force period acts as a reinforcer. [•] Experiment 2 demonstrates sensitivity to delay as a parameter of choice in a self-control paradigm. [•] The results of the two experiments indicate a functional similarity between primary reinforcers used in non-human subjects and the present reinforcer. [•] So this procedure is well-suited to study operant conditioning in humans. [Copyright &y& Elsevier]

Highlights: [•] Effects of signaled reinforcer magnitude on delayed matching-to-sample performance were examined in individuals with intellectual disabilities. [•] Matching accuracy was overall higher when the signal indicated the upcoming reinforcer was rich. [•] Signaled reinforcer magnitude affected initial discriminability but not rate of forgetting. [Copyright &y& Elsevier]

Abstract: The relative-coding hypothesis of temporal discrimination asserts that humans learn to respond to the relative duration of stimuli (“short” and “long”). The most frequently used procedure to test the hypothesis is the double bisection task. In one task, participants learn that red and green are the correct comparisons following 2s (short) and 5s (long) samples respectively. In another task, participants learn that triangle and circle are the correct comparisons following 3.5s (short) and 6.5s (long) samples, respectively. Later the samples of one task are tested with the comparisons of the other task, and vice versa. According to the hypothesis, participants will choose red following a 3.5s sample because that sample is short and red is the comparison that goes with short. Similarly, they will choose circle following 5s samples because that sample is long and circle goes with long. We replicated this procedure and improved it by introducing several sample durations during testing to obtain the whole psychometric function of each task. Results from Experiment 1 only partially corroborated the relative-coding hypothesis. Results from Experiment 2 did not corroborate the hypothesis. The combined data from Experiments 1 and 2 partially corroborate the hypothesis. Alternatively, we present an explanation of relative-coding-like results that posits exclusively absolute coding of temporal stimuli. This article is part of a Special Issue entitled: SQAB 2012. [Copyright &y& Elsevier]

Abstract: We investigated the animal and human baby schema effect (BSE) in relation to gender, parental status, and individual features. In three, independent online surveys, conducted during three consecutive years, (N total =1389), ratings of photographs of human and animal infants as well as of adults, sociodemographic variables (age, gender, parental status) and personality attributes (empathy, attachment, interpersonal closeness, narcissism, and need to belong) were assessed. We demonstrated that humans are sensitive to the baby schemata of both humans and animals and that both are weakly positively correlated. BSE is positively associated with female gender and (affective) empathy. Higher interpersonal closeness and need to belong were additionally connected specifically to the human BSE. In contrast, narcissism and insecure attachment were not related to the BSE, suggesting a robustness of this phenomenon to possible negative influences of these two personality attributes. [Copyright &y& Elsevier]

Abstract: Functional relationships (from systematic manipulation of critical variables) are advocated for revealing fundamental processes of (comparative) cognition—through examples from my work in psychophysics, learning, and memory. Functional relationships for pigeon wavelength (hue) discrimination revealed best discrimination at the spectral points of hue transition for pigeons—a correspondence (i.e., functional relationship) similar to that for humans. Functional relationships for learning revealed: Item-specific or relational learning in matching to sample as a function of the pigeons’ sample-response requirement, and same/different abstract-concept learning as a function of the training set size for rhesus monkeys, capuchin monkeys, and pigeons. Functional relationships for visual memory revealed serial position functions (a 1st order functional relationship) that changed systematically with retention delay (a 2nd order relationship) for pigeons, capuchin monkeys, rhesus monkeys, and humans. Functional relationships for rhesus-monkey auditory memory also revealed systematic changes in serial position functions with delay, but these changes were opposite to those for visual memory. Functional relationships for proactive interference revealed interference that varied as a function of a ratio of delay times. Functional relationships for change detection memory revealed (qualitative) similarities and (quantitative) differences in human and monkey visual short-term memory as a function of the number of memory items. It is concluded that these findings were made possible by varying critical variables over a substantial portion of the manipulable range to generate functions and derive relationships. [Copyright &y& Elsevier]

Abstract: The present study examined whether equivalent discounting of delayed rewards is observed with different experimental procedures. If the underlying decision-making process is the same, then similar patterns of results should be observed regardless of procedure, and similar estimates of the subjective value of future rewards (i.e., indifference points) should be obtained. Two experiments compared discounting on three types of procedure: adjusting-delay (AD), adjusting-immediate-amount (AIA), and adjusting-delayed-amount (ADA). For the two procedures for which discounting functions can be established (i.e., AD and AIA), a hyperboloid provided good fits to the data at both the group and individual levels, and individuals’ discounting on one procedure tended to be correlated with their discounting on the other. Notably, the AIA procedure produced the more consistent estimates of the degree of discounting, and in particular, discounting on the AIA procedure was unaffected by the order in which choices were presented. Regardless of which of the three procedures was used, however, similar patterns of results were obtained: Participants systematically discounted the value of delayed rewards, and robust magnitude effects were observed. Although each procedure may have its own advantages and disadvantages, use of all three types of procedure in the present study provided converging evidence for common decision-making processes underlying the discounting of delayed rewards. [Copyright &y& Elsevier]

Abstract: Spatial integration refers to the superimposition of two separate spatial relationships between cues (C1–C2 and C2–C3) by a common linking element (C2). This linkage creates a new spatial relationship between cues that were never paired together (C1–C3). Several authors obtained conflicting results on spatial integration in both humans and animals. Using a dynamic 3D virtual environment, we provide the first clear evidence that humans can integrate two spatial relationships into a new spatial relationship that guides spatial navigation. This research is discussed in light of a spatial version of the temporal coding hypothesis (). [Copyright &y& Elsevier]

Abstract: The present experiment examined whether, in a matching-to-sample (MTS) procedure, a relation between two stimuli, a sample and a comparison, could be established as a result of just stimulus–stimulus pairing, even if back up reinforcers were never provided for the conditional relation between the sample and comparison stimuli, but rather only for the comparison stimulus. A procedure called “pseudo matching-to-sample” was used in which, when S1 was presented as a sample stimulus, two comparison stimuli (C1 and C2) were presented, and only responses to C1 were reinforced. Conversely, when S2 was presented, only responses to C3 (and not C4) were reinforced. In other words, organisms experiencing this procedure could discriminate C1 from C2, and C3 from C4, by simple discrimination without regard to the conditional sample stimuli. In order to examine cross-species differences, responding by humans in this procedure was compared to that by pigeons. Although the humans developed a discriminative function for the sample stimuli, that is, the humans’ responding was affected by both the sample stimuli and the reinforcers, responding by the pigeons was affected solely by the reinforcers. These data suggest that, in this procedure, humans (but not pigeons) are able to learn relations among stimuli simply as a result of stimulus–stimulus pairing. [Copyright &y& Elsevier]

Abstract: The availability of alternative reinforcers reduces drug taking. Escalating alternative reinforcer values have been used to initiate and maintain abstinence from drug use. A reset in reinforcer value has been added to the schedule of alternative reinforcer presentation to discourage relapse. The purpose of this preliminary study was to test the influence of escalating and escalating and resetting alternative reinforcer value on cigarette choice in the human laboratory. Fourteen daily cigarette smokers completed this experiment, which required one practice and three experimental sessions. During each experimental session, subjects made six choices between smoking a cigarette and receiving money, available under Constant, Escalating or Escalating and Resetting conditions. The total number of cigarettes chosen and puffs taken, but not the maximum consecutive number of cigarettes choices, was decreased in the Escalating condition relative to the Constant condition. The maximum number of consecutive cigarettes chosen was decreased in the Escalating and Resetting condition relative to the Constant condition. The proportion of money earned was increased in the Escalating condition relative to the Constant and Escalating and Resetting conditions. These initial findings indicate that whereas an escalating alternative reinforcer schedule reduces cigarette smoking overall, an escalating and resetting alternative reinforcer schedule may reduce repeated cigarette smoking (i.e., relapse). [Copyright &y& Elsevier]

Abstract: Delay discounting refers to the tendency for outcomes that are remote in time to have less value than more immediate outcomes. Steep discounting of delayed outcomes is associated with a variety of social maladies. The degree of sensitivity to delayed outcomes may be a stable and pervasive individual characteristic. In analyses of archival data, the present study found positive correlations between the degree of delay discounting for one outcome (as measured by the Area Under the Curve), and the degree of discounting for other outcomes. Along with additional evidence reviewed, these data suggest that delay discounting may be considered a personality trait. Recent research in epigenetics, neuroscience, and behavior suggests delay discounting may prove to be a beneficial target for therapeutic attempts to produce global reductions in impulsivity related to delay discounting. [Copyright &y& Elsevier]

Abstract: When humans buy a lottery ticket or gamble at a casino they are engaging in an activity that on average leads to a loss of money. Although animals are purported to engage in optimal foraging behavior, similar sub-optimal behavior can be found in pigeons. They show a preference for an alternative that is associated with a low probability of reinforcement (e.g., one that is followed by a red hue on 20% of the trials and then reinforcement or by a green hue on 80% of the trials and then the absence of reinforcement) over an alternative that is associated with a higher probability of reinforcement (e.g., blue or yellow each of which is followed by reinforcement 50% of the time). This effect appears to result from the strong conditioned reinforcement associated with the stimulus that is always followed by reinforcement. Surprisingly, although it is experienced four times as much, the stimulus that is never followed by reinforcement does not appear to result in significant conditioned inhibition (perhaps due to the absence of observing behavior). Similarly, human gamblers tend to overvalue wins and undervalue losses. Thus, this animal model may provide a useful analog to human gambling behavior, one that is free from the influence of human culture, language, social reinforcement, and other experiential biases that may influence human gambling behavior. [Copyright &y& Elsevier]

Abstract: Recently, have advanced a behavior-economic approach to measure the value of reinforcers, in which demand elasticity is measured relative to the point at which price is zero, a technique that allows for comparisons across reinforcers that show different consumption patterns or across different dosages or magnitudes of the same reinforcer. The authors have proposed an exponential model in which the elasticity coefficient measures the essential value of reinforcers. The application of the exponential model in various experiments has shown that it provided a good fit to the data and supplied different theoretically consistent results. Considering that this previous research has either been experimentally based or has involved nonhuman participants, the present work examined the application of the model to the analysis of changes in consumption of brands with changes in prices, employing data from actual consumers buying brands of food products in grocery shopping, differing in the level of informational (i.e., socially mediated) and utilitarian (i.e., product mediated) reinforcement they offered. Purchase information concerning two products was obtained from a consumer panel, which included data related to purchases of more than 1600 consumers during 52 weeks. The model, calculated for different brands, fitted the data only moderately, but its parameters showed good reliability across stores. The essential value of brands showed significant increases with increases in brand informational reinforcement. The results indicate the reliability of the measure of essential value as its application is extended from the closed setting of the laboratory to the open settings of the marketplace and to symbolic secondary reinforcers. [Copyright &y& Elsevier]

Abstract: Disoriented men and women were trained to search for a goal hidden in front of one of four objects forming a rectangular-shaped array. The angular properties of these objects (either 50° or 75°) served as local geometric cues and the rectangular shape of the array served as global geometric cues. Upon successful completion of training, transformation tests were conducted during which either the local angle cues were removed and the global geometry was preserved (Global Cues test) or the local angles were preserved and the global geometry was removed (Local Cues test). A Cue Conflict test was also conducted which placed the local geometry in direct competition with the global geometry for control of search behavior. Results from testing showed that neither men nor women could successfully use only the global geometric cues provided by the shape of the array to reorient. Analyses of sex differences for the use of local cues revealed that men showed clear evidence that they had successfully encoded the local angular cues whereas women did not. Furthermore, the size of the training angle may have affected the encoding of local cues. [Copyright &y& Elsevier]

Abstract: A comparative study was conducted to investigate whether the search for a target letter was facilitated when the target and prime (preceding stimulus) letters were identical. Pigeons (Section ) and human participants (Section ) were first trained to search for “A” among “Y”s and “E” among “D”s in a condition in which a square shape appeared as the prime (Neutral condition). In subsequent testing, a prime was identical either to the corresponding target (Target-priming condition) or to the distractor (Distractor-priming condition). Humans and pigeons responded differently to the two priming conditions. On early trials, the Target prime facilitated search in humans, reducing reaction times (RTs) to targets. In pigeons, however, RTs were longer with Target primes, suggesting that pre-exposure to target letters may directly inhibit the search for targets in subsequent search displays. Furthermore, pre-exposure to the distractor letters may inhibit the processing of the distractor. On later trials, RTs of humans were faster in both priming conditions than in the Neutral condition, suggesting that expectation of a target facilitated search (“Y” predicted “A” and “D” predicted “E”). In contrast, the pigeons showed no evidence of expectation-based facilitation, with constant slowing effects of the Target prime extending across sessions. Possible mechanisms underlying such a slowing priming effect in pigeons were discussed. [ABSTRACT FROM AUTHOR]

Abstract: Past studies using the concurrent-chain procedure showed that pigeons and humans generally prefer an unsegmented schedule to a segmented schedule. This finding is ostensibly inconsistent with theories of conditioned reinforcement such as delay-reduction theory. In the present study with humans, two changes in the basic segmented schedule were implemented to resolve this inconsistency. The first change was that in the segmented schedule the terminal-link stimulus (S+ stimulus) changed late in the terminal-link, close to reinforcement presentation. The second change was that the presentation of the segmenting stimulus, S+, was brief allowing a reinstatement of the early terminal-link stimulus, which is contiguous with reinforcement. Our data constitute the first demonstration of preference for the segmented schedule when a brief S+ is correlated with a greater reduction in delay to reinforcement. [Copyright &y& Elsevier]

Abstract: Dog owners were surveyed for observations of social behaviors in their dogs, using questions adapted from the human Autism Diagnostic Observation Schedule (ADOS) pre-verbal module. Using 939 responses for purebred and mixed-breed dogs, three factors were identified: initiation of reciprocal social behaviors (INIT), response to social interactions (RSPNS), and communication (COMM). There were small or no effects of sex, age, breed group or training. For six breeds with more than 35 responses (Border Collie, Rough Collie, German Shepherd, Golden Retriever, Labrador Retriever, Standard Poodle), the behaviors eye contact with humans, enjoyment in interactions with human interaction, and name recognition demonstrated little variability across breeds, while asking for objects, giving/showing objects to humans, and attempts to direct humans’ attention showed higher variability across these breeds. Breeds with genetically similar backgrounds had similar response distributions for owner reports of dog response to pointing. When considering these breeds according to the broad categories of “herders” and “retrievers,” owners reported that the “herders” used more eye contact and vocalization, while the “retrievers” used more body contact. Information regarding social cognitive abilities in dogs provided by owner report suggest that there is variability across many social cognitive abilities in dogs and offers direction for further experimental investigations. [Copyright &y& Elsevier]

Abstract: This experiment was conducted to study the effect of changes in the retention interval (RI) on spontaneous recovery within an acquisition-test interference task. College students learned a reversal conditional discrimination to solve a task involving conflicting phases across two training phases. When the test was conducted immediately after training, participants’ performance revealed recency, behaving according to the information received during the last phase. Performance after retention interval averaged the information received across phases, regardless of the length of the RI (1.5, 3, 24 or 48h). These results are not in agreement with traditonal theories of spontaneous recovery as they predict a recency to primacy shift effect of the RI. An interpretation of spontaneous recovery based on a temporal weighting rule (TWR) is discussed. [Copyright &y& Elsevier]

Abstract: The goal was to identify training conditions under which temporal intervals that are signaled by different stimuli are memorized (i.e., the temporal behavior is readily shown to be under stimulus control). Undergraduate students were trained on three signaled temporal discriminations using a peak procedure. The intervals were trained in either blocks of trials or with trials intermixed within the session, and then they were given a transfer test with intermixed trials. There were two levels of stimulus discriminability, defined by the similarity of the stimuli. Most participants memorized the intervals when the discriminations were intermixed within the session, or were easy, but not when the discriminations occurred in blocks and were difficult. In the transfer tests, those participants trained in the difficult discrimination that occurred in blocks of trials typically continued to perform as they did during the last-trained interval, regardless of the stimulus presented. These results are better explained by a memory retrieval than a memory storage account. [Copyright &y& Elsevier]

Abstract: Previously, we () showed that two-parameter hyperboloid models () provide significantly better fits to delay discounting data than simple, one-parameter hyperbolic and exponential models. Here, we extend this effort by comparing fits of the two-parameter hyperboloid models to data from a larger sample of participants (N =171) who discounted probabilistic as well as delayed rewards. In particular, we examined the effects of amount on the exponents in the two hyperboloid models of delay and probability discounting in order to evaluate key theoretical predictions of the standard psychophysical scaling interpretation of these exponents. Both the Rachlin model and the Green and Myerson model provided very good fits to delay and probability discounting of both small and large amounts at both the group and individual levels (all R 2s>.97 at the group level; all median R 2s>.92 at the individual level). For delay discounting, the exponent in both models did not vary as a function of delayed amount, consistent with the psychophysical scaling interpretation. For probability discounting, however, the exponent in both models increased as the probabilistic amount increased—a finding inconsistent with the scaling interpretation. [Copyright &y& Elsevier]

Abstract: The present experiment provided a replication in humans of an experimental procedure that has been used frequently with nonhumans to investigate choice behaviour in a changing environment. Six volunteers played a computer game, which required tracking of a moving balloon on two simultaneously available response panels for monetary reinforcers. Each of the 15 sessions randomly arranged the following concurrent variable-interval reinforcement schedules, which were in effect until six reinforcers had been obtained: 27:1, 9:1, 3:1, 1:1, 1:3, 1:9, and 1:27. Although many aspects of human performance appeared to be qualitatively similar to that of nonhumans on this procedure, such as the rapid preference shifts towards the within-session reinforcer ratios and the presence of local effects of reinforcers, values of sensitivity to reinforcement were very variable in the present study, as commonly reported in human choice studies. Future variations and refinements of the experimental methods are needed to explore how this variability may be reduced. [Copyright &y& Elsevier]

Abstract: Adult human subjects engaged in a simulated Rock/Paper/Scissors game against a computer opponent. The computer opponent''s responses were determined by programmed probabilities that differed across 10 blocks of 100 trials each. Response allocation in Experiment 1 was well described by a modified version of the generalized matching equation, with undermatching observed in all subjects. To assess the effects of instructions on response allocation, accurate probability-related information on how the computer was programmed to respond was provided to subjects in Experiment 2. Five of 6 subjects played the counter response of the computer''s dominant programmed response near-exclusively (e.g., subjects played paper almost exclusively if the probability of rock was high), resulting in minor overmatching, and higher reinforcement rates relative to Experiment 1. On the whole, the study shows that the generalized matching law provides a good description of complex human choice in a gaming context, and illustrates a promising set of laboratory methods and analytic techniques that capture important features of human choice outside the laboratory. [Copyright &y& Elsevier]

Abstract: The modality of a stimulus and its intermittency affect time estimation. The present experiment explores the effect of a combination of modality and intermittency, and its implications for internal clock explanations. Twenty-four participants were tested on a temporal bisection task with durations of 200–800ms. Durations were signaled by visual steady stimuli, auditory steady stimuli, visual flickering stimuli, and auditory clicks. Psychophysical functions and bisection points indicated that the durations of visual steady stimuli were classified as shorter and more variable than the durations signaled by the auditory stimuli (steady and clicks), and that the durations of the visual flickering stimuli were classified as longer than the durations signaled by the auditory stimuli (steady and clicks). An interpretation of the results is that there are different speeds for the internal clock, which are mediated by the perceptual features of the stimuli timed, such as differences in time of processing. [Copyright &y& Elsevier]

Abstract: The present study compared four prominent models of delay discounting: a one-parameter exponential decay, a one-parameter hyperbola [Mazur, J.E., 1987. An adjusting procedure for studying delayed reinforcement. In: Commons, M.L., Mazur, J.E., Nevin, J.A., Rachlin, H. (Eds.), Quantitative Analyses of Behavior: The Effect of Delay and of Intervening Events on Reinforcement Value, vol. 5. Erlbaum, Hillsdale, NJ, pp. 55–73], a two-parameter hyperboloid in which the denominator is raised to a power [Green, L., Myerson, J., 2004. A discounting framework for choice with delayed and probabilistic rewards. Psychol. Bull. 130, 769–792], and a two-parameter hyperbola in which delay is raised to a power [Rachlin, H., 2006. Notes on discounting. J. Exp. Anal. Behav. 85, 425–435]. Sixty-four college undergraduates made choices between hypothetical monetary rewards, one immediate and one delayed, and the fit of the four models to their data was assessed. All four equations accounted for a large proportion of the variance at both the group and the individual levels, but the exponents of both two-parameter models were significantly less than 1.0 at the group level, and frequently so at the individual level. Taken together, these results strongly suggest that more than one parameter is needed to accurately describe delay discounting by humans. Notably, both the Rachlin and the Green and Myerson models accounted for more than 99% of the variance at the group level and for 96% of the variance in the median individual. Because both models provide such good descriptions of the data, model selection will need to be based on other grounds. [Copyright &y& Elsevier]

Abstract: Davison and Baum [Davison, M., Baum, W. M., 2000. Choice in a variable environment: every reinforcer counts. Journal of the Experimental Analysis of Behavior 74, 1–24.] developed a concurrent-schedule procedure where, within each session, different reinforcer ratios were arranged across components separated by brief black-outs. Behaviour adapted quickly to the reinforcer ratios and reinforcers also had local effects on responding. This procedure has been used with pigeons and rats. In the present experiment, we adapted the Davison and Baum procedure to study the effects of reinforcement on human choice behaviour. Eighteen participants were presented with four different reinforcer ratios within a single 50-minute session. Mean sensitivity to the reinforcer ratios increased within components, and preference was greater for the just-reinforced response alternative immediately following reinforcer delivery, similar to the results from non-human experiments. Although there were limitations to the current procedure, the local time scale analyses are a novel way of examining human operant behaviour. [Copyright &y& Elsevier]

Abstract: In an experiment involving a new behavioural preparation the role played by similarity in discrimination learning was examined using visual patterns (i.e., paintings) that might share common elements (specifically, A, BC, and ABC). A–C were small stars of three specific colours (target colours), which were intermixed with other stars of two different colours (distracting colours). The target colours were balanced through A–C. Students received discrimination training in which a fictitious painter was the author of paintings A and BC, while paintings ABC were assigned to a second fictitious painter. During training, the students had to make a choice, in the presence of each pattern, between two response keys, each of them indicating one of the painters. The time taken to respond was also measured. Feedback was always given after each key-press. The results showed that while at times the A+ ABC− discrimination was acquired more readily than was the BC+ ABC− discrimination, on other occasions the reverse was also true, the critical factor being the way in which the colours were combined. [Copyright &y& Elsevier]

Abstract: This experiment investigated the effects of visual flicker on subjective time in humans using a temporal bisection task. A 200–800ms duration range and 400–1600ms duration range were presented. Each duration range was presented separately in three different conditions: (1) filled stimuli were presented in both the training and the testing phases, (2) flickering stimuli were presented in the training phase and filled stimuli were presented in the testing phase, and (3) filled stimuli were presented in the training phase and flickering stimuli were presented in the testing phase. Psychophysical functions displacements and bisection point values suggested that flicker increased the speed of the clock; however the direction of the displacement and bisection point changes depended on the phase of the task in which the flicker was presented. This result agrees with the specific storage in either working or reference memory components of Scalar Expectancy Theory of the increased number of pulses from the clock. Weber fractions and difference limens suggested that flicker did not affect subjects’ temporal sensitivity. [Copyright &y& Elsevier]

Abstract: In Experiment 1, each of three humans knowledgeable about operant schedules used mouse clicks to respond to a “work key” presented on a monitor. On a random half of the presentations, work-key responses that completed a variable ratio (VR) 12 produced a tone. After five tones, the work key was replaced by two report keys. Pressing the right or left report key, respectively, added or subtracted ¥50 from a counter and produced the work key. On the other half of the presentations, a variable interval (VI) associated with the work key was defined so its interreinforcer intervals approximated the time it took to complete the variable ratio. After five tone-producing completions of this schedule, the report keys were presented. Left or right report-key presses, respectively, added or subtracted ¥50 from the counter. Subjects achieved high yen totals. In Experiment 2, the procedure was changed by requiring an interresponse time after completion of the variable interval that approximated the duration of the reinforced interresponse time on the variable ratio. Prior to beginning, subjects were shown how a sequence of response bouts and pauses could be used to predict schedule type. Subjects again achieved high levels of accuracy. These results show humans can discriminate ratio from interval schedules even when those schedules provide the same rate of reinforcement and reinforced interresponse times. [Copyright &y& Elsevier]

Abstract: Humans and macaques are more sensitive to differences in nonaccidental image properties, such as straight vs. curved contours, than to differences in metric properties, such as degree of curvature [Biederman, I., Bar, M., 1999. One-shot viewpoint invariance in matching novel objects. Vis. Res. 39, 2885–2899; Kayaert, G., Biederman, I., Vogels, R., 2003. Shape tuning in macaque inferior temporal cortex. J. Neurosci. 23, 3016–3027; Kayaert, G., Biederman, I., Vogels, R., 2005. Representation of regular and irregular shapes in macaque inferotemporal cortex. Cereb. Cortex 15, 1308–1321]. This differential sensitivity allows facile recognition when the object is viewed at an orientation in depth not previously experienced. In Experiment 1, we trained pigeons to discriminate grayscale, shaded images of four shapes. Pigeons made more confusion errors to shapes that shared more nonaccidental properties. Although the images in that experiment were not well controlled for incidental changes in metric properties, the same results were apparent with better controlled stimuli in Experiment 2: pigeons trained to discriminate a target shape from a metrically changed shape and a nonaccidentally changed shape committed more confusion errors to the metrically changed shape, suggesting that they perceived it to be more similar to the target shape. Humans trained with similar stimuli and procedure exhibited the same tendency to make more errors to the metrically changed shape. These results document the greater saliency of nonaccidental differences for shape recognition and discrimination in a non-primate species and suggest that nonaccidental sensitivity may be characteristic of all shape-discriminating species. [Copyright &y& Elsevier]

Abstract: Any attempt to understand the nature of behaviorism as a philosophy of science, to depict the essence of its distinctive explanatory system, or to delimit the scope of its capacity to explicate behavior, requires an appreciation of how its practitioners use language. Three behaviorist theories that are especially relevant to the explanation of economic behavior – radical behaviorism, teleological behaviorism, and picoeconomics – provide a necessary array of theoretical perspectives in that each contributes uniquely to understanding consumer choice. Despite the differences that separate them at a methodological level, and the internecine disputes in which their adherents sometimes address one another, these three perspectives play complementary roles in the depiction of everyday consumer behavior. Moreover, this combination of behavior theories owes much to the way in which each has responded to the challenge of intentional explanation. In order to demonstrate this, the paper proposes a framework of analysis which portrays the essential differences between intentional explanation and the extensional approach towards which many behaviorists have striven, and argues that while radical behaviorism scrupulously avoids intentional terms, teleological behaviorism and picoeconomics have in differing ways come to terms with the necessity of combining a behaviorist perspective with the explanatory value of intentional terminology. This continuum of explanations is applied to recent findings of consumer behavior analysis on consumer choice in natural environments. [Copyright &y& Elsevier]

Abstract: Two experiments were conducted with the aim of designing a videogame for the study of human conditioned avoidance. Participants had to destroy enemy spaceships with the goal of increasing the score in a counter. Coloured signals might announce the launching of a bomb that could hit participant''s spaceship producing a 30 points decrease in participant''s score. Three groups of participants were trained in discriminating between a warning signal (W) and a safety signal (S) in Experiment 1. Instrumental group could avoid the loss of points by hiding the spaceship before the offset of W. Participants in the Yoked group received the same treatment received by their instrumental partners, regardless of their behaviour. In the Pavlovian group, W was always followed by the loss of points, regardless of participant''s behaviour. Discrimination between W and S was better in the Instrumental groups than in the Yoked and Pavlovian control groups. Experiment 2 found extinction of avoidance when the warning signal was not followed by the bomb. Temporal discrimination was found within the participants that received the instrumental contingency in both experiments, with higher avoidance response towards the end of the warning signal. Temporal discrimination disappeared after extinction in Experiment 2. [Copyright &y& Elsevier]

Abstract: Two distinct conceptualisations of processing mechanisms have been proposed in the research on the perception of temporal order, one that assumes a central-timing mechanism that is involved in the detection of temporal order independent of modality and stimulus type, another one assuming feature-specific mechanisms that are dependent on stimulus properties. In the present study, four different temporal-order judgement tasks were compared to test these two conceptualisations, that is, to determine whether common processes underlie temporal-order thresholds over different modalities and stimulus types or whether distinct processes are related to each task. Measurements varied regarding modality (visual and auditory) and stimulus properties (auditory modality: clicks and tones; visual modality: colour and position). Results indicate that the click and the tone paradigm, as well as the colour and position paradigm, correlate with each other. Besides these intra-modal relationships, cross-modal correlations show dependencies between the click, the colour and the position tasks. Both processing mechanisms seem to influence the detection of temporal order. While two different tones are integrated and processed by a more independent, possibly feature-specific mechanism, a more central, modality-independent timing mechanism contributes to the click, colour and position condition. [Copyright &y& Elsevier]

A group of 15 college students was exposed to repeated trials of a task in which money was available for choosing among three colors (blue, red, and green). The amount of winning tokens for each color was varied across phases to test whether group distribution would track the ratio of winning tokens between patches. Confirming previous reports on ideal free performance in humans, group choice proved sensitive to the available resources but tended to undermatch the ratio of winning tokens. The difference-equalization rule of Sokolowski, Tonneau, and Freixa i Baque´ [Psychonom. Bull. Rev. 6 (1999) 157] gave a satisfactory fit to the data. [Copyright &y& Elsevier]

An experiment explored the effects of context change (renewal) and presentation of the outcome (reinstatement) upon retroactive interference in causal learning. An interference task was used where a sequential relationship between the name of a food and two different outcomes was established (A+|A*). Renewal and reinstatement effects appeared as partial attenuation of retroactive interference. The combination of both treatments produced complete recovery of first-learned information (A+). This complete reversal on the estimations of participants suggests that renewal and reinstatement effects within this paradigm imply partial recovery of the first-learned information, rather than response at a chance level emitted by confused participants. On the other hand, additivity between reinstatement and renewal suggests that reinstatement may be due to the combined effect of different underlying processes. [Copyright &y& Elsevier]

Two experiments attempted to manipulate the decision processes used in a temporal generalisation task with humans. In Experiment 1, payoffs (points awarded or deducted) were used to try to alter behaviour when the standard duration was 400 ms, and the comparison durations ranged from 100 to 700 ms in 100 ms steps. Two conditions which either encouraged or discouraged the subject to identify a comparison duration as the standard were compared with a neutral condition. Encouraging identifications of the standard increased the proportion of identifications of the standard, whereas the discouraging manipulation had more ambiguous effects. Using the “modified Church and Gibbon” model, it was shown that the effect of the encourage manipulation was an increase in the response threshold, consistent with the information-processing version of scalar timing theory. A second experiment compared encourage and discourage manipulations with a more difficult discrimination (comparison durations spaced in 50 ms steps around the 400 ms standard), and with more distinct payoff differences for the different conditions. Behavioural effects were much more marked in Experiment 2, with the encourage condition producing more identifications of a comparison duration as the standard for all comparison durations except the shortest, compared with the discourage condition. Modelling showed that the main theoretical difference between the two conditions was in a change in the response threshold, in a manner consistent with the scalar timing model. [Copyright &y& Elsevier]

This article summarizes the potential role of evolved brain emotional systems in the mediation of music appreciation. A variety of examples of how music may promote behavioral change are summarized, including effects on memory, mood, brain activity as well as autonomic responses such as the experience of ‘chills’. Studies on animals (e.g. young chicks) indicate that musical stimulation have measurable effects on their behaviors and brain chemistries, especially increased brain norepinephrine (NE) turnover. The evolutionary sources of musical sensitivity are discussed, as well as the potential medical-therapeutic implications of this knowledge. [Copyright &y& Elsevier]

The prisoner''s dilemma is much studied in social psychology and decision-making because it models many real-world conflicts. In everyday terms, the choice to ‘cooperate’ (maximize reward for the group) or ‘defect’ (maximize reward for the individual) is often attributed to altruistic or selfish motives. Alternatively, behavior during a dilemma may be understood as a function of reinforcement and punishment. Human participants played a prisoner''s-dilemma-type game (for points exchangeable for money) with a computer that employed either a teaching strategy (a probabilistic version of tit-for-tat), in which the computer reinforced or punished participants’ cooperation or defection, or a learning strategy (a probabilistic version of Pavlov), in which the computer''s responses were reinforced and punished by participants’ cooperation and defection. Participants learned to cooperate against both computer strategies. However, in a second experiment which varied the context of the game, they learned to cooperate only against one or other strategy; participants did not learn to cooperate against tit-for-tat when they believed that they were playing against another person; participants did not learn to cooperate against Pavlov when the computer''s cooperation probability was signaled by a spinner. The results are consistent with the notion that people are biased not only to cooperate or defect on individual social choices, but also to employ one or other strategy of interaction in a pattern across social choices. [Copyright &y& Elsevier]