Exemplar accounts of blending and distinctiveness effects in perceptual old-new recognition

Recent findings from the perceptual old-new recognition literature indicate that observers have extremely high false-alarm rates to new items that are "blends" of old ones. In addition, evidence suggests that "distinctive" old items--that is, those located in isolated regions of the similarity space--are recognized with higher probability than are typical old items. Both types of phenomena challenge the predictions of global-familiarity exemplar models of perceptual old-new recognition, which posit that the probability that an observer judges an item as old is based on its summed similarity to previously presented exemplars. In the present research the authors pursued these blending and distinctiveness effects by testing paradigms in which similarity relations among objects are highly controlled and in which the variables of blending and distinctiveness are not confounded with other properties associated with the individual objects themselves. In contrast to previous results, the authors found effects of blending and distinctiveness that are compatible with the predictions of a pure summed-similarity exemplar model.     

Speeded recognition of ungrammaticality: Double violations

A model of sentence comprehension postulating that Subject-Verb-Object relations are specified prior to Noun-Adjective relations received support from a study of the speed at which sentences with various kinds of violations could be rejected. Compatible with the sequential model was the finding that Noun-Verb and Adjective-Noun double violations did not result in shorter RTs than Noun-Verb single violations — even though sentences with double violations were judged to be less acceptable.     

Cognitive processing of multidimensional stimuli in schizophrenia: formal modeling of judgment speed and content

This article presents a formal, mathematical account of relations between response times on simple cognitive tasks and content of complex judgments involving multiple stimulus dimensions for people with schizophrenia. Changes in multidimensional judgments were viewed as the result of interference from increased stages of encoding with respect to the individual dimensions. Information on dimensional properties encoded earlier in a judgment trial was considered to be more susceptible to loss over the rest of the trial, because of a larger number of encoding stages applied to the remaining dimensional properties. Model predictions were tested with samples of paranoid and nonparanoid schizophrenic participants and controls. Unidimensional encoding speed was assessed by reaction times in an explicit similarity ratings task, and multidimensional judgment content was assessed by the relative importance of different stimulus dimensions to participants' ratings in an implicit similarity ratings task. Results support validity of the model.     

Human perceptual performance with nonliteral imagery: region recognition and texture-based segmentation

In this study the authors address the issue of how the perceptual usefulness of nonliteral imagery should be evaluated. Perceptual performance with nonliteral imagery of natural scenes obtained at night from infrared and image-intensified sensors and from multisensor fusion methods was assessed to relate performance on 2 basic perceptual tasks to fundamental characteristics of the imagery. Specifically, single-sensor imagery and fused multisensor imagery (both achromatic and false color) were used to test performance on a region recognition task and a texture segmentation task. Results indicate that the use of color rendering and type of scene content play specific roles in determining perceptual performance allowed by nonliteral imagery. The authors argue that the usefulness of various image-rendering methods should be evaluated with respect to multiple perceptual tasks.     

A feature-sampling account of the time course of old-new recognition judgments

This article describes the feature-sampling theory of recognition (FESTHER), a new model of the time course of recognition judgments based on a model of the time course of perceptual processing in categorization (K. Lamberts, 1995, 1998). FESTHER is applied to previous results and to data from 4 old-new recognition experiments. Experiments 1 and 2 provided a preliminary test of the model's ability to explain recognition judgments of simple objects under response deadlines. Experiments 3 and 4 involved a response-signal procedure to elicit recognition judgments at different time lags after presentation of a stimulus. Simple objects and words were used as stimuli in Experiments 3 and 4, respectively. The new model accounts well for the data from the 4 experiments and offers a parsimonious account of the time course of recognition judgments based on the time-dependent availability of stimulus information.     

On the relation between decision rules and perceptual representation in multidimensional perceptual categorization

This article examines the relation between changing categorization decision rules and the nature of the underlying perceptual representation. Observers completed a matching task that required them to adjust the length and orientation of a single line stimulus until they perceived it to "match" a second line stimulus (Alfonso-Reese, 1996, 1997). The same observers then completed four categorization tasks with the same stimuli. Data from the matching task were used to estimate a perceptual representation for each stimulus and observer. Three hypotheses regarding potential interactions between categorization decision rules and perceptual representation were examined. One assumed that there was no interaction between decision rules and perceptual representation. The second assumed that linear categorization rules affect the perceptual representation differently from nonlinear categorization rules. The third assumed that dimensional integration rules affected the perceptual representation differently from decision rules that require the observer to set a criterion along one stimulus dimension while ignoring the other; this is referred to as decisional selective attention. The results suggested that (1) the matching task perceptual representation provided a good account of the categorization data, (2) decisional selective attention affected the perceptual representation differently from decisional integration, and (3) decisional selective attention generally decreased the perceptual variability along the attended dimension.     

Interpreting ambiguous stimuli: Separating perceptual and judgmental biases

Interpreting ambiguous situations is not a purely data-driven process but can be biased towards positive interpretations by top-down influences. The present study tries to identify the underlying processes of these top-down influences. There are two separable types of processes that can be influenced by motivational biases: A perceptual bias affects information uptake whereas a judgmental bias affects acceptance criteria for positive and negative outcomes. In the present study, motivated influences on perception and judgment were investigated with a simple color discrimination task in which ambiguous stimuli had to be classified according to their dominating color. One of two colors indicated a financial gain or a loss, whereas a third color was neutral. To separate perceptual and judgmental biases, Ratcliff’s [Ratcliff, R. (1978). A theory of memory retrieval. Psychological Review, 85, 59–108] diffusion model was employed. Results revealed motivational influences on perception and judgment.     

Direct estimation of multidimensional perceptual distributions: assessing hue and form

The procedures developed to assess the perceptual and decisional processes associated with detection in multidimensional space all require specialized statistical skills and analysis programs. The present article describes a regression model, designed to assess dimensional interactions, that is both computationally simpler and more accessible than those procedures. The papervalidates the regression model by comparing the perceptual space associated with the detection of hue and form mapped by the regression model with that mapped by Kadlec and Townsend's (1992a, 1992b) macro- and microanalyses. The results of both analyses showed that hue strongly influences the perception of form but that form only weakly influences the perception of hue. The parallel results of the two analyses suggest that the regression model is a valid alternative to multidimensional signal detection theory analysis.     

Preferential processing of self-relevant stimuli occurs mainly at the perceptual and conscious stages of information processing

Self-related stimuli, such as one’s own name or face, are processed faster and more accurately than other types of stimuli. However, what remains unknown is at which stage of the information processing hierarchy this preferential processing occurs. Our first aim was to determine whether preferential self-processing involves mainly perceptual stages or also post-perceptual stages. We found that self-related priming was stronger than other-related priming only because of perceptual prime-target congruency. Our second aim was to dissociate the role of conscious and unconscious factors in preferential self-processing. To this end, we compared the “self” and “other” conditions in trials where primes were masked or unmasked. In two separate experiments, we found that self-related priming was stronger than other-related priming but only in the unmasked trials. Together, our results suggest that preferential access to the self-concept occurs mainly at the perceptual and conscious stages of the stimulus processing hierarchy.     

Decision rules in the perception and categorization of multidimensional stimuli

This article examines decision processes in the perception and categorization of stimuli constructed from one or more components. First, a general perceptual theory is used to formally characterize large classes of existing decision models according to the type of decision boundary they predict in a multidimensional perceptual space. A new experimental paradigm is developed that makes it possible to accurately estimate a subject's decision boundary in a categorization task. Three experiments using this paradigm are reported. Three conclusions stand out: (a) Subjects adopted deterministic decision rules, that is, for a given location in the perceptual space, most subjects always gave the same response; (b) subjects used decision rules that were nearly optimal; and (c) the only constraint on the type of decision bound that subjects used was the amount of cognitive capacity it required to implement. Subjects were not constrained to make independent decisions on each component or to attend to the distance to each prototype.     

Focused attention in the perception and retrieval of multidimensional stimuli

This paper reports some further experiments on successive matching of multidimensional stimuli in which the correct conjunctions of features must be specified; it also modifies and extends the model proposed earlier by Treisman, Sykes, and Gelade (1977). The results obtained in the previous experiment were replicated despite a change from fixed to varied targets, and from spatial to temporal separation of the targets, thus extending their generality. The modified conjunction-matching model proposes that the subject progressively narrows his focus of attention, first to deal with a single display stimulus at a time and finally, if necessary, to a single target. The model was tested quantitatively by simulating the separate stages hypothesized to underlie conjunction-matching in some simpler, single-attribute-matching conditions, and using the differences between latencies in these conditions to predict differences between latencies in the appropriate conjunction-matching conditions. The results were consistent with the general hypothesis that one important role of focused attention and serial processing is to integrate separable attributes or features into the correct conjunctions, which correspond to the objects actually presented or stored.     

PsychoPro 2.0: Using multidimensional scaling to examine the perceptual categorization of race

Recently, researchers examining cognitive mechanisms involved in the detection of racial markers have been using psychophysics to examine perceptual thresholds delineating race using a program called PsychoPro (MacLin, MacLin, Peterson, Chowdhry, & Joshi, 2009). PsychoPro allows researchers to collect data using facial stimuli morphed along a racial continuum with psychophysical methodology. PsychoPro 2.0 was updated so researchers could collect paired-comparison data that can then be analyzed using multidimensional scaling (MDS). MDS allows researchers to examine the perceptions of racial boundaries along perceptual dimensions not bounded by the stimulus continuum, by having the observer make paired comparisons to racial stimuli based on their perceived similarity. Results indicate that ratings were made on the basis of at least six different racial dimensions that suggest the emergence of a third race not represented by the original morph starting images. Details of the software, the new paired-comparison feature and its relevance in psychophysical studies in general and racial categorization in particular are presented.     

Signal-detection models for multidimensional stimuli: Probability distributions and combination rules

Probabilistic independence among multiple random variables (e.g., among the outputs of multiple spatial-frequency channels) has been invoked to explain two effects found with many kinds of stimuli: increments in detection performance due to “probability summation” and decrements in detection and identification performance due to “extrinsic uncertainty.” Quantitative predictions of such effects, however, depend on the precise assumptions. Here we calculate predictions from multidimensional signal-detection theory assuming any of several different probability distributions characterizing the random variables (including two-state, Gaussian, exponential, and double-exponential distributions) and either of two rules for combining the multiple random variables into a single decision variable (taking the maximum or summing them). In general, the probability distributions predicting shallower ROC curves predict greater increments due to summation but smaller decrements due to extrinsic uncertainty. Some probability distributions yield steep-enough ROC curves to actually predict decrements due to summation in blocked-summation experiments. Probability distribution matters much less for intermixed-summation than for blocked-summation predictions. Of the two combination rules, the sum-of-outputs rule usually predicts both greater increments due to summation and greater decrements due to extrinsic uncertainty. Put another way, of the two combination rules, the sum-of-outputs rule usually predicts better performance on the compound stimulus under any condition but worse performance on simple stimuli under intermixed conditions.     

Classifying multidimensional stimuli: stimulus, task, and observer factors

When observers decide how to classify stimuli, they often employ one of two types of information: identity along one particular dimension or overall similarity. The present studies examined interrelations among the factors which determine the use of these types of information. Participants' classifications of certain types of materials (e.g., size and brightness, length and density) revealed strong individual differences, were related to the individual's response tempo and selective processing ability, and were influenced by task demands. Classifications of other materials (e.g., saturation and brightness) did not reveal individual differences, were not affected by response tempo and selective processing ability, and were unaffected by changes in task demands. The former, but not the latter, types of materials have also been found to be influenced by developmental differences. The results are consistent with the idea that differences in response tempo and selective processing ability underlie observer differences (both individual and developmental) and that certain types of stimuli which are not susceptible to such influences set boundary conditions for observer differences. The results are discussed within an integral-to-separable model of processing.     

On the processing of simple visual and auditory stimuli at distinct levels

Two RT studies explored the possibility that identification of a single stimulus can take place through more than one perceptual route. In the first experiment, mean RT to color was systematically changed by varying type of catch stimulus. In the second experiment, the form of the RT distribution to a tone was changed by varying type of catch stimulus. Considerations of distribution means and shapes led to the conclusion that detection and discrimination are two of the alternative levels of perceptual processing which can be evoked in rapid identification of these stimuli.     

Restricting the field of view: perceptual and performance effects

Visual perception involves both the high acuity of foveal vision and the wide scope of overlapping peripheral information. The role of peripheral vision in competent performance of the adult visuomotor activities of walking, reaching, and forming a cognitive map of a room was examined using goggles which limited the scope of the normal field of view to 9 degrees, 14 degrees, 22 degrees, or 60 degrees. Each restriction of peripheral field information resulted in some perceptual and performance decrements, with the 9 degrees and 14 degrees restriction producing the most disturbance. In addition, bodily discomfort, dizziness, unsteadiness and disorientation, were reported as the subjects moved around with restricted fields of view.     

Perceptibility of schematic face stimuli: Evidence for a perceptual Gestalt

The perceptibility of face, scrambled face, and single-feature stimuli was investigated in three experiments. Stimuli were presented tachistoscopically, followed by a visual noise mask and a forced-choice test of one of three features (eyes, nose, and mouth). In Experiment I, two processing strategies which have been proposed for word perception (involving expectancy and redundancy) were investigated for the stimuli employed here. In Experiments II and III, experimentally induced familiarity was studied for its effect on recognition and perception, and an immediate and delayed perceptual test was employed. Across all three experiments, perception of single-feature and face stimuli were consistently superior to scrambled faces; in Experiment III, differences between single features and faces were eliminated. The effects of perceptual expectancy, internal feature redundancy, familiarity, guessing biases, etc., were shown to be insufficient to account for the superiority of face to scrambled face stimuli. It was argued that the perceptibility of nonredundant features are enhanced when those features are aligned in a well-defined form class. The view that familiarity operates directly on recognitive processes but indirectly on perceptual ones was discussed.     

Selective attention in the speeded classification and comparison of multidimensional stimuli

Selective attention was studied when subjects were required to make either speeded classifications of single stimuli or comparisons of pairs of multidimensional stimuli. Experiment 1 established that subjects were able to attend selectively to form when the irrelevant dimension of size or shading varied in a speeded-classification (card-sorting) task. Experiment 2 confirmed this finding in a discrete-trials task. However, subjects werenot able to filter out irrelevant dimensional disparity in a comparably designed simultaneous-comparison (i.e., “same”-“different”) task. Mean “same” reaction time increased monotonically with increases in disparity between the two stimuli on the irrelevant dimension. Experiment 3 also revealed a monotonie increase in “same” RT as a function of irrelevant disparity in a successive-comparison task. These results were discussed in terms of a normalization model proposed by Dixon and Just (1978) in which it is assumed that a subject equates the two stimuli on the irrelevant dimension before deciding that they are the same along the relevant dimension. It was concluded that: (1) although subjects can efficiently filter out irrelevant disparity in a speeded-classification task, interference due to irrelevant disparity is obtained in the comparison tasks, (2) a common process such as normalization does not necessarily underlie performance in the speeded-classification and comparison tasks, (3) the ability to attend selectively to a stimulus dimension may be task determined as well as stimulus determined, and (4) contrary to the Dixon and Just proposal, normalization of irrelevant disparity occurs in a comparison task, even when the relevant dimension is represented as a separate encoding feature.