Search

The exponential race model embodied in the theory of visual attention (TVA) and the power law generalization of the sample size model (SSPL) provide competing accounts of the mechanisms that determine how exposure duration, set size, and attention influence how many items enter visual short-term memory (VSTM). In the exponential race model, items compete for entry into VSTM in a processing race with exponentially distributed processing times. The most recent version of the sample size model assumes that target sensitivity measured by d ' increases monotonically as a function of exposure duration and decreases as a power function of set size. Here we compare the two models in a new experiment with letters and Gabor patches and with data from five previously published experiments. This was done by applying TVA to the two-alternative forced-choice method (2AFC), which forms the basis of the experimental work on the sample size model. Both models fitted individual participants' proportions of correct trials quite well, and overall the fits by the two models were almost indistinguishable. This was confirmed by formal pairwise comparison of TVA and SSPL by the Akaike information criterion and the Bayesian information criterion measures. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Based on the simple what first comes to mind rule, the theory of visual attention (TVA; Bundesen, 1990) provides a comprehensive account of visual attention that has been successful in explaining performance in visual categorization for a variety of attention tasks. If the stimuli to be categorized are mutually confusable, a response rule based on the amount of evidence collected over a longer time seems more appropriate. In this paper, we extend the idea of a simple race to continuous sampling of evidence in favor of a certain response category. The resulting Poisson random walk model is a TVA-based response time model in which categories are reported based on the amount of evidence obtained. We demonstrate that the model provides an excellent account for response time distributions obtained in speeded visual categorization tasks. The model is mathematically tractable, and its parameters are well founded and easily interpretable. We also provide an extension of the Poisson random walk to any number of response alternatives. We tested the model in experiments with speeded and nonspeeded binary responses and a speeded response task with multiple report categories. The Poisson random walk model agreed very well with the data. A thorough investigation of processing rates revealed that the perceptual categorizations described by the Poisson random walk were the same as those obtained from TVA. The Poisson random walk model could therefore provide a unifying account of attention and response times. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The relationship between visual attentional selection of items in particular spatial locations and selection by nonspatial criteria was investigated in a partial report experiment with report of letters (as many as possible) from brief postmasked exposures of circular arrays of letters and digits. The data were fitted by mathematical models based on Bundesen's (Psychological Review, 97, 523-547, 1990) theory of visual attention (TVA). Both attentional weights of targets (letters) and attentional weights of distractors (digits) showed strong variations across the eight possible target locations, but for each of the ten participants, the ratio of the weight of a distractor at a given location to the weight of a target at the same location was approximately constant. The results were accommodated by revising the weight equation of TVA such that the attentional weight of an object equals a product of a spatial weight component (weight due to being at a particular location) and a nonspatial weight component (weight due to having particular features other than locations), the two components scaling the effects of each other multiplicatively.

Conventional wisdom on psychological experiments has held that when one or more independent variables are manipulated it is essential that all other conditions are kept constant such that confounding factors can be assumed negligible (Woodworth, 1938). In practice, the latter assumption is often questionable because it is generally difficult to guarantee that all other conditions are constant between any two trials. Therefore, the most common way to check for confounding violations of this assumption is to split the experimental conditions in terms of "trial types" to simulate a reduction of unintended trial-by-trial variation. Here, we pose a method which is more general than the use of trial types: use of mathematical models treating measures of potentially confounding factors and manipulated variables as equals on the single-trial level. We show how the method can be applied with models that subsume under the generalized linear item response theory (GLIRT), which is the case for most of the well-known psychometric models (Mellenbergh, 1994). As an example, we provide a new analysis of a single-letter recognition experiment using a nested likelihood ratio test that treats manipulated and measured variables equally (i.e., in exactly the same way) on the single-trial level. The test detects a confounding interaction with time-on-task as a single-trial measure and yields a substantially better estimate of the effect size of the main manipulation compared with an analysis made in terms of trial types.

Temporal expectation is expectation with respect to the timing of an event such as the appearance of a certain stimulus. In this paper, temporal expectancy is investigated in the context of the theory of visual attention (TVA), and we begin by summarizing the foundations of this theoretical framework. Next, we present a parametric experiment exploring the effects of temporal expectation on perceptual processing speed in cued single-stimulus letter recognition with unspeeded motor responses. The length of the cue-stimulus foreperiod was exponentially distributed with one of six hazard rates varying between blocks. We hypothesized that this manipulation would result in a distinct temporal expectation in each hazard rate condition. Stimulus exposures were varied such that both the temporal threshold of conscious perception (t0 ms) and the perceptual processing speed (v letters s(-1)) could be estimated using TVA. We found that the temporal threshold t0 was unaffected by temporal expectation, but the perceptual processing speed v was a strikingly linear function of the logarithm of the hazard rate of the stimulus presentation. We argue that the effects on the v values were generated by changes in perceptual biases, suggesting that our perceptual biases are directly related to our temporal expectations.

The attentional weight of a visual object depends on the contrast of the features of the object to its local surroundings (feature contrast) and the relevance of the features to one's goals (feature relevance). We investigated the dependency in partial report experiments with briefly presented stimuli but unspeeded responses. The task was to report the letters from a mixture of letters (targets) and digits (distractors). Color was irrelevant to the task, but many stimulus displays contained an item (target or distractor) in a deviant color (a color singleton). The results showed concurrent effects of feature contrast (color singleton vs. nonsingleton) and relevance (target vs. distractor). A singleton target had a higher probability of being reported than did a nonsingleton target, and a singleton distractor interfered more strongly with report of targets than did a nonsingleton distractor. Measured by use of Bundesen's (1990) computational theory of visual attention, the attentional weight of a singleton object was nearly proportional to the weight of an otherwise similar nonsingleton object, with a factor of proportionality that increased with the strength of the feature contrast of the singleton. This result is explained by generalizing the weight equation of Bundesen's (1990) theory of visual attention such that the attentional weight of an object becomes a product of a bottom-up (feature contrast) and a top-down (feature relevance) component., (PsycINFO Database Record (c) 2013 APA, all rights reserved.)

Many researchers interpret switch costs in the explicit task-cuing procedure as reflecting endogenous task-set reconfiguration. G. D. Logan and C. Bundesen (2003) challenged this interpretation empirically and theoretically. They argued that many experiments confounded cue encoding benefits with switch costs and they showed that unconfounded switch costs could be vanishingly small. They proposed a theory in which subjects use a single task set in the explicit task-cuing procedure and switch costs reflect cue encoding benefits, not reconfiguration. S. Monsell and G. A. Mizon (2006) responded to these challenges, describing conditions under which substantial switch costs could be observed in the explicit task-cuing procedure and providing a theoretical account of performance in which reconfiguration occurred in G. D. Logan and C. Bundesen's experiments. This article is a response to S. Monsell and G. A. Mizon's challenge that highlights empirical problems with their evidence and reports an experiment that challenges critical assumptions of their theoretical account., ((c) 2007 APA, all rights reserved)

A neural theory of visual attention (NTVA) is presented. NTVA is a neural interpretation of C. Bundesen's (1990) theory of visual attention (TVA). In NTVA, visual processing capacity is distributed across stimuli by dynamic remapping of receptive fields of cortical cells such that more processing resources (cells) are devoted to behaviorally important objects than to less important ones. By use of the same basic equations used in TVA, NTVA accounts for a wide range of known attentional effects in human performance (reaction times and error rates) and a wide range of effects observed in firing rates of single cells in the primate visual system. NTVA provides a mathematical framework to unify the 2 fields of research--formulas bridging cognition and neurophysiology.

In two experiments, subjects were given arbitrary letter cues or meaningful word cues that specified the task to be performed on a subsequent target stimulus. Letter and word cues were presented in separate blocks. There were two cues of each type for each task. Three kinds of transitions separated tasks: cue repetitions, in which both the cue and the task repeated; task repetitions, in which the cue changed but the task repeated; and task alternations, in which both the cue and the task changed. Responses were faster for cue than for task repetitions for both cue types. With word cues, task repetitions were not reliably faster than task alternations. With letter cues, task repetitions were reliably faster than task alternations in the first block but not in the second block. The results suggest that subjects responded to the compound of the cue and the target rather than switching task set between trials.

Does the explicit task-cuing procedure require an endogenous a act of control? In 5 experiments, cues indicating which task to perform preceded targets by several stimulus onset asynchronies (SOAs). Two models were developed to account for changes in reaction time (RT) with SOA. Model 1 assumed an endogenous act of task switching for cue alterations but not for cue repetitions. Model 2 assumed no such act. In Experiments 1 and 2, the cue was masked or not masked. Masking interacted underadditively with repetition and alternation, consistent with Model 2 but not Model 1. In Experiments 3 and 4, 2 cues were used for each task. RT was slower for task repetition than for cue repetition and about the same as RT for task alternation, consistent with Model 2 but not Model 1. The results suggest that the explicit task-cuing procedure does not require an endogenous act of control.

In a partial-report experiment, subjects reported the digits from a circular array of digits and letters terminated by a pattern mask. Individual frequency distributions of the number of correctly reported digits were analyzed as functions of number of digits (2, 4, or 6) and number of letters (0, 2, 4, 6, or 8) at nine exposure durations ranging from 10 to 200 ms. The distributions (hundreds of data points per subject) were accurately predicted by a four-parameter fixed-capacity independent race model that assumes exponentially distributed processing times, limitations in both processing capacity and storage capacity, and time-invariant selectivity. Estimated from the data, processing capacity C was 45 items/s, selectivity alpha (ratio between the amount of processing capacity devoted to a distractor and the amount devoted to a target) was 0.48, short-term storage capacity K was 3.5 items, and the longest ineffective exposure duration t0 was 18 ms.