The prioritization of perceptual processing in categorization

In three experiments, the effects of selective attention on perceptual processes in a complex multidimensional object categorization task were investigated. In each experiment, participants completed a perceptual-matching task to gain estimates of the perceptual salience of each stimulus dimension, then a categorization task using the same stimuli. In Experiments 1 and 2, the perceptual processing of stimulus dimensions was faster when dimensions were more diagnostic of category membership, regardless of their perceptual salience. Experiment 3 demonstrated that this prioritization of perceptual processing was evident even when stimuli were presented in unpredictable locations during categorization, indicating that the physical characteristics of the stimulus guide selective attention to diagnostic stimulus dimensions.     

Rate of perceptual processing

Summary The primary goal of Schulze and Schuster's (1977) experiment was to test Massaro's (1972) hypothesis that the rate of processing of the auditory image after the tone is turned off is equal to the rate of processing the stimulus code while the stimulus is present. The experiment was unsuccessful, however, since the authors did not take into account corresponding changes in the asymptote parameter of the model with changes in stimulus duration. This review discusses the problem in detail along with a general discussion of model testing and appropriate experimental procedure.This research was supported by Public Health Service Grant MH-19399. Wendy L. Idson provided valuable comments. Requests for offprints should be sent to Dominic W. Massaro, Department of Psychology, University of Wisconsin, Johnson at Charter Streets, Madison, Wisconsin 53706, USA     

The specificity of perceptual learning in speech processing

We conducted four experiments to investigate the specificity of perceptual adjustments made to unusual speech sounds. Dutch listeners heard a female talker produce an ambiguous fricative [?] (between [f] and [s]) in [f]- or [s]-biased lexical contexts. Listeners with [f]-biased exposure (e.g., [witlo?]; from witlof, "chicory"; witlos is meaningless) subsequently categorized more sounds on an [epsilonf]-[epsilons] continuum as [f] than did listeners with [s]-biased exposure. This occurred when the continuum was based on the exposure talker's speech (Experiment 1), and when the same test fricatives appeared after vowels spoken by novel female and male talkers (Experiments 1 and 2). When the continuum was made entirely from a novel talker's speech, there was no exposure effect (Experiment 3) unless fricatives from that talker had been spliced into the exposure talker's speech during exposure (Experiment 4). We conclude that perceptual learning about idiosyncratic speech is applied at a segmental level and is, under these exposure conditions, talker specific.     

The time course of perceptual choice: the leaky, competing accumulator model

The time course of perceptual choice is discussed in a model of gradual, leaky, stochastic, and competitive information accumulation in nonlinear decision units. Special cases of the model match a classical diffusion process, but leakage and competition work together to address several challenges to existing diffusion, random walk, and accumulator models. The model accounts for data from choice tasks using both time-controlled (e.g., response signal) and standard reaction time paradigms and its adequacy compares favorably with other approaches. A new paradigm that controls the time of arrival of information supporting different choice alternatives provides further support. The model captures choice behavior regardless of the number of alternatives, accounting for the log-linear relation between reaction time and number of alternatives (Hick's law) and explains a complex pattern of visual and contextual priming in visual word identification.     

Wholistic and analytic stimulus processing: The development of selective perceptual strategies

This experiment reports an investigation of the development of selective processing strategies as subjects become increasingly more practised at a serial self-paced RT task. It demonstrates the effect a preceding stimulus can have on the analysis of a current signal and the development of active analytic strategies in favour of passive wholistic processing, with practice. The stimuli used were letters with irrelevant visual noise dot patterns superimposed on them. The letter, or the dot pattern, or both, could be repeated on successive trials. Early in practice repetition of both stimulus components simultaneously produced short reponse latencies relative to repetition of the letter alone. The number of noise dots markedly affected RT. Late in practice, however, letter repetition RTs were small, irrespective of whether or not the noise dot pattern was repeated. Furthermore, the number of noise dots no longer had an effect on the RT to these stimulus transitions. The results suggest that subjects appear to be able to select relevant information to process as they become progressively more practised, even though there is evidence that they compare the current stimulus with an iconic representation of the immediately preceding one.     

The role of perceptual load in processing distractor faces

It has been established that successful ignoring of irrelevant distractors depends on the extent to which the current task loads attention. However, the previous load studies have typically employed neutral distractor stimuli (e.g., letters). In the experiments reported here, we examined whether the perception of irrelevant distractor faces would show the same effects. We manipulated attentional load in a relevant task of name search by varying the search set size and found that whereas congruency effects from meaningful nonface distractors were eliminated by higher search load, interference from distractor faces was entirely unaffected by search load. These results support the idea that face processing may be mandatory and generalize the load theory to the processing of meaningful and more complex nonface distractors.     

Linguistic cues enhance the learning of perceptual cues

When language is correlated with regularities in the world, does it enhance the learning of these regularities? This question lies at the core of both notions of linguistic bootstrapping in children and the Whorfian hypothesis. Support for an affirmative answer is provided in an artificial-noun-learning task in which 2-year-old children were taught to distinguish categories of solid and nonsolid things with and without supporting correlated linguistic cues.     

Holistic processing of faces: perceptual and decisional components

Researchers have used several composite face paradigms to assess holistic processing of faces. In the selective attention paradigm, participants decide whether one face part (e.g., top) is the same as a previously seen face part. Their judgment is affected by whether the irrelevant part of the test face is the same as or different than the relevant part of the study face. This failure of selective attention implies holistic processing. However, the authors show that this task alone cannot distinguish between perceptual and decisional sources of holism. The distinction can be addressed by the complete identification paradigm, in which both face parts are judged to be same or different, combined with analyses based on general recognition theory (F. G. Ashby & J. T. Townsend, 1986). The authors used a different paradigm, sequential responses, to relate these 2 paradigms empirically and theoretically. Sequential responses produced the same results as did selective attention and complete identification. Moreover, disruptions of holistic processing by systematic misalignment of the faces corresponded with systematic and significant changes in the decisional components, but not in the perceptual components, that were extracted using general recognition theory measures. This finding suggests a significant decisional component of holistic face processing in the composite face task.     

Global perceptual processing in problem solving: The case of the traveling salesperson

The traveling salesperson problem (TSP) consists of finding the shortest tour around a set of locations and is an important task in computer science and operations research. In four experiments, the relationship between processes implicated in the recognition of good figures and the identification of TSP solutions was investigated. In Experiment 1, a linear relationship was found between participants’ judgments of good figure and the optimality of solutions to TSPs. In Experiment 2, identification performance was shown to be a function of solution optimality and problem orientation. Experiment 3 replicated these findings with a forced-pace method, suggesting that global processing, rather than a local processing strategy involving point-by-point analysis of TSP solutions, is the primary process involved in the derivation of best figures for the presented TSPs. In Experiment 4, the role of global precedence was confirmed using a priming method, in which it was found that short (100 msec) primes facilitated solution identification, relative to no prime or longer primes. Effects of problem type were found in all the experiments, suggesting that local features of some problems may disrupt global processing. The results are discussed in terms of Sanocki’s (1993) global-to-local contingency model. We argue that global perceptual processing may contribute more generally to problem solving and that human performance can complement computational TSP methods.     

The effects of perceptual load on semantic processing under inattention

Inattentional blindness refers to a failure to consciously detect an irrelevant object that appears without any expectation when attention is engaged with another task. The perceptual load theory predicts that task-irrelevant stimuli will reach awareness only when the primary task is of low load, which allows processing resources to spill over to processing task-irrelevant stimuli as well. We studied whether perceptual load has an effect on inattentional blindness for a task-irrelevant stimulus whose meaning is or is not relevant to the attentional goals of the observer. In the critical trial, a word appeared without any expectation in the center of a display of attended pictures. The results showed that, under both high and low load, unexpected words belonging to the attended semantic category were detected more often than semantically unrelated words. These results imply that task-irrelevant stimuli, whose meanings are relevant to the observer’s task, enter awareness irrespective of perceptual load.     

Great expectations: Temporal expectation modulates perceptual processing speed

In a crowded dynamic world, temporal expectations guide our attention in time. Prior investigations have consistently demonstrated that temporal expectations speed motor behavior. We explore effects of temporal expectation on perceptual speed in three nonspeeded, cued recognition paradigms. Different hazard rate functions for the cue-stimulus foreperiod were used to manipulate temporal expectations. By computational modeling we estimated two distinct components of visual attention: the temporal threshold of conscious perception (t? ms) and the speed of subsequent encoding into visual short-term memory (v items/s). Notably, these components were measured independently of any motor involvement. The threshold t? was unaffected by temporal expectation, but perceptual processing speed v increased with increasing expectation. By employing constant hazard rates to keep expectation constant over time, we further confirmed that the increase in perceptual speed was independent of the cue-stimulus duration. Thus, our results strongly suggest temporal expectations optimize perceptual performance by speeding information processing. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Configural processing at birth: evidence for perceptual organisation

We report a series of ten experiments aimed to investigate the newborn's ability to discriminate the components of a visual pattern and to process the visual information that specifies the global configuration of a stimulus. The results reveal that: (i) newborn babies are able to distinguish individual elements of a stimulus (experiments 1A, 1B, 1C, and 1D); (ii) they can group individual elements into a holistic percept on the basis of Gestalt principles (experiments 2A and 3A); (iii) their spontaneous preferences cannot be easily modified by habituation (experiments 2B and 3B); and (iv) when horizontal stimuli are paired with vertical stimuli, they prefer the horizontal ones (experiments 4A and 4B).     

The supplementary motor area in motor and perceptual time processing: fMRI studies

The neural bases of timing mechanisms in the second-to-minute range are currently investigated using multidisciplinary approaches. This paper documents the involvement of the supplementary motor area (SMA) in the encoding of target durations by reporting convergent fMRI data from motor and perceptual timing tasks. Event-related fMRI was used in two temporal procedures, involving (1) the production of an accurate interval as compared to an accurate force, and (2) a dual-task of time and colour discrimination with parametric manipulation of the level of attention attributed to each parameter. The first study revealed greater activation of the SMA proper in skilful control of time compared to force. The second showed that increasing attentional allocation to time increased activity in a cortico-striatal network including the pre-SMA (in contrast with the occipital cortex for increasing attention to colour). Further, the SMA proper was sensitive to the attentional modulation cued prior to the time processing period. Taken together, these data and related literature suggest that the SMA plays a key role in time processing as part of the striato-cortical pathway previously identified by animal studies, human neuropsychology and neuroimaging.     

Heterosocial perceptual organization: application of the choice model to sexual coercion

Luce's (1959, 1963) choice model was used to characterize individual differences in men's perception of women's affect as friendly, sexually interested, sad, or rejecting. Women's clothing styles were associated with differences in the model's parameters. Sensitivity to sadness, rejection, and friendliness declined when women were dressed provocatively, whereas sensitivity to sexual interest increased. Provocative clothing was also associated with an increased bias to assume that positive affect was sexual interest rather than friendliness. Men at risk for perpetrating sexual aggression were less sensitive to women's affect than low-risk men were. They were also more likely than low-risk men to associate provocative clothing with sexual interest, and conservative clothing with friendliness. Results indicate that heterosocial perception may help to predict sexually coercive behavior and may be an important target for intervention.     

The attentional blink is susceptible to concurrent perceptual processing demands

In a rapid serial visual presentation stream processing of a first target (T1) impairs detection or identification of a second target (T2) that appears within 500 ms after T1. This effect characterizes the so-called attentional blink (AB). To evaluate contemporary information-processing accounts of the AB phenomenon in terms of the underlying processing mechanisms the present study examined the potential influence of Task 1 difficulty on the AB effect. To this end, T1 contrast and T1 response requirements were systematically varied across four experiments. Experiment 1 ruled out a mere sensory basis of the contrast manipulation on T2 performance. When only T2 had to be reported (Experiment 2) an AB effect occurred that was slightly modulated by T1 contrast. When report of both T1 and T2 was required in a standard AB task (Experiment 3), the magnitude of the AB depended to a larger extent on stimulus contrast, and it increased further when speeded T1 choice responses were additionally required (Experiment 4). On the basis of the present impact of Task 1 difficulty on the AB effect we conclude that processing limitations cause the AB phenomenon. We discuss such limitations in terms of perceptual (T1 consolidation) and central (response selection) bottleneck processes.     

Discrete vs. continuous processing: The fate of an incompletely processed perceptual dimension

A relevant issue in the debate on continuous vs. discrete processing of information is whether incompletely processed information does or does not affect a subsequent reaction. Two stimuli (SL, SR) were presented on eye level, subtending a visual angle of 45 degrees. SL was always inspected first, followed by a saccade to SR and finally by a same/different response. The fixation time of SL (TL), the saccadic time (TM) and the time from fixating SR to the response (TR) were separately measured. SL and SR consisted of two-dimensional stimuli (size and letter shape) constructed in such a way that encoding size took longer for one group and encoding shape took longer for another group of 10 subjects. All subjects were tested in three conditions: Shape was relevant in one, size in the second, and both dimensions were relevant in the third condition.

TL was less when encoding the relevant dimension was fast. When both dimensions were relevant, TL was about as long as when only the slow dimension was relevant, suggesting parallel and interference-free processing during TL. When only the slow dimension was relevant, TR (same) was much longer when the fast dimension differed. When the fast dimension was relevant, TR (same) was slightly longer when the slow dimension differed, which can be handled by either model. The experiment was repeated with three well-practiced and less variable subjects who carried out sufficient trials to measure TR as a function of TL. The results of this study were in line with the discrete model: A different slow and irrelevant dimension did not affect the same response regardless of the duration of TL. Interestingly, subjects were capable of retrieving the slow dimension, suggesting a code which can be used for retrieval but which does not affect the same/different response.     

Enhanced perceptual processing of speech in autism

Theories of autism have proposed that a bias towards low-level perceptual information, or a featural/surface-biased information-processing style, may compromise higher-level language processing in such individuals. Two experiments, utilizing linguistic stimuli with competing low-level/perceptual and high-level/semantic information, tested processing biases in children with autism and matched controls. Whereas children with autism exhibited superior perceptual processing of speech relative to controls, and showed no evidence of either a perceptual or semantic processing bias, controls showed a tendency to process speech semantically. The data provide partial support to the perceptual theories of autism. It is additionally proposed that the pattern of results may reflect different patterns of attentional focusing towards single or multiple stimulus cues in speech between children with autism and controls.     

Task-set reconfiguration and perceptual processing: behavioral and electrophysiological evidence

Oriet and Jolic?ur (2003) proposed that an endogenous task-set reconfiguration process acts as a hard bottleneck during which even early perceptual processing is impossible. We examined this assumption using a psychophysiological approach. Participants were required to switch between magnitude and parity judgment tasks within a predictable task sequence while event-related potentials (ERPs) were recorded. Stimulus contrast and response stimulus interval (RSI) were manipulated. Behavioral data demonstrated typical task switch costs that decreased as RSI increased. However, whereas ERP analysis of visual ERP component latencies sensitively revealed the contrast effect, a switch-specific postponement of perceptual processing during task-set reconfiguration at short RSIs was not observed. The present findings indicate that the process of task-set reconfiguration does not constitute a hard bottleneck that delays perceptual processing.