Optional processes in similarity judgments

This research investigates the nature of similarity relations among three pairs of interacting dimensions: (1) the integral dimensions of auditory pitch and loudness, (2) the configurai dimensions of paired parentheses, and (3) the cross-modally corresponding dimensions of visual position and auditory pitch. We evaluated the rules by which information from each dimension combines in similarity judgments. Our claim is that, when judging similarity, processes that are obligatory, or what we call mandatory processes, can commingle with processes of choice, or what we call optional processes. By varying instructions, we found strong evidence of optional processing. Instructions to rate overall similarity encouraged subjects to attend to stimuli as wholes and led to a Euclidean rule in similarity scaling. Instructions to focus on dimensions encouraged subjects to consider each stimulus dimension separately and led to a city-block rule. We argue that optional processes may obscure mandatory ones, and so need to be identifled-beforernandatory processes can be understood.     

Optional processes in similarity judgments.

This research investigates the nature of similarity relations among three pairs of interacting dimensions: (1) the integral dimensions of auditory pitch and loudness, (2) the configural dimensions of paired parentheses, and (3) the cross-modally corresponding dimensions of visual position and auditory pitch. We evaluated the rules by which information from each dimension combines in similarity judgments. Our claim is that, when judging similarity, processes that are obligatory, or what we call mandatory processes, can commingle with processes of choice, or what we call optional processes. By varying instructions, we found strong evidence of optional processing. Instructions to rate overall similarity encouraged subjects to attend to stimuli as wholes and led to a Euclidean rule in similarity scaling. Instructions to focus on dimensions encouraged subjects to consider each stimulus dimension separately and led to a city-block rule. We argue that optional processes may obscure mandatory ones, and so need to be identified before mandatory processes can be understood.     

Relational similarity and the nonindependence of features in similarity judgments

Four experiments examined the hypothesis that simple attributional features and relational features operate differently in the determination of similarity judgments. Forced choice similarity judgments ("Is X or Y more similar to Z?") and similarity rating tasks demonstrate that making the same featural change in two geometric stimuli unequally affects their judged similarity to a third stimulus (the comparison stimulus). More specifically, a featural change that causes stimuli to be more superficially similar and less relationally similar increases judged similarity if it occurs in stimuli that already share many superficial attributes, and decreases similarity if it occurs in stimuli that do not share as many superficial attributes. These results argue against an assumption of feature independence which asserts that the degree to which a feature shared by two objects affects similarity is independent of the other features shared by the objects. The MAX hypothesis is introduced, in which attributional and relational similarities are separately pooled, and shared features affect similarity more if the pool they are in is already relatively large. The results support claims that relations and attributes are psychologically distinct and that formal measures of similarity should not treat all types of matching features equally.     

Structural alignment in similarity and difference judgments

Similarity is a central construct in models of cognitive processing, and as such has been the focus of psychological inquiry. This work has revealed that similarity and difference judgments are not always inverses. One explanation for this effect is that similarity judgments focus on matching relations between the items, while difference judgments focus on the mismatching attributes. A second explanation is that both similarity and difference judgments involve a process of structural alignment, and that they use the output of this process differently. These views are contrasted by using the one-shot mapping technique that places attribute similarity and relational similarity in competition. The results suggest that similarity and difference judgments both involve structural alignment.     

Sequences of similarity judgments as time series

Sequences of similarity judgments made to pairs of geometrical patterns with three variable elements were obtained from 22 subjects. Each subject made 100 judgments to a series which embodied random input, step transitions and impulse shifts. Three different instructions concerning the use of information from previous trials were used. Time series analyses gave linear transfer function coefficients whose ratios reflected the strategy employed by a subject. Evidence of local nonstationarity in the response gain functions is examined.     

A choice theory analysis of similarity judgments

The selection of one of several stimuli as most similar to a reference stimulus is assumed to satisfy a choice axiom that permits assigning ratio scale values to each variable-reference stimuli pair. The logarithm of this scale is treated as a distance measure, leading to the following testable conclusions about the pairwise choice probabilities as the reference stimulus is varied. First, the plot is a symmetrically truncated ogive with horizontal tails. Second, if two pairs of choice stimuli have the same midpoint, the ogive of one pair is part of the ogive of the other. In terms of this model, the hysteresis and midpoint displacement effects in the method of bisection are discussed, and relations with Coombs' unfolding techniques are explored.This work was supported in part by grant G-8864 from the National Science Foundation to the University of Pennsylvania. I wish to express my appreciation to Professors Robert R. Bush and Eugene Galanter, with whom I have had a number of very helpful discussions of these ideas.     

Expectancy,controlled attention and automatic attention in prospective temporal judgments

Two experiments indicate that prospective judgments of a temporal target are influenced by nontarget temporal features. The basic task was to reproduce a target interval marked by visual events. In addition, visual or auditory interfering events were delivered. Experiment 1 showed that temporal reproduction is shorter when the interfering events occupy a late rather than early position during the target interval, a result explained in terms of expectancy, which causes attention shifts. This study also revealed that similar trends are obtained whether the interfering event involves a specific task or is irrelevant. Experiment 2 confirmed the position effect, and showed that the duration of an irrelevant cue can influence judgment of the target interval, as if it were also timed without appropriate control.     

Localization judgments under various levels of attention

We investigated the effects of attention on localization with two converging manipulations of attention. The results indicated that whereas attention improved localization, minimally attended stimuli were nonetheless localized fairly accurately. The distributions of localization responses around peripheral stimuli were asymmetric, with a greater dispersion along the axis linking fixation to stimulus location relative to its perpendicular axis. We propose that the unattended field comprises attentional receptive fields that are mediated by coarse location detectors. We speculate that attention produces fine localization by facilitating computations that integrate the relative activation of overlapping detectors.     

Relative judgments affect assessments of stimulus duration

Humans were trained on two independent temporal discriminations, with correct choice dependent on the initial stimulus duration. In Experiment 1, the durations were 1.0 and 4.0 sec, with one set of choice stimuli, and 2.0 and 8.0 sec, with a different set of choice stimuli. The 2.0- and 4.0-sec values were selected to be the geometric mean of the two values in the other discrimination. In Experiment 2, the durations were 2.0 and 5.0 sec for one discrimination and 3.5 and 6.5 sec for the other. The 3.5- and 5.0-sec values were selected to be the arithmetic mean of the two values in the other discrimination. In both experiments, participants showed evidence for relational coding of the duration pairs. That is, the test durations were selected to be at the presumed bisection point (i.e., they should have produced indifferent choice), but instead the shorter test duration from the longer duration pair produced a “short” bias (in both experiments), whereas the longer duration from the shorter duration pair produced a “long” bias (in the second experiment). Results were similar to those from Zentall, Weaver, and Clement (2004) with pigeons.     

Predicting similarity judgments in intertemporal choice with machine learning

Similarity models of intertemporal choice are heuristics that choose based on similarity judgments of the reward amounts and time delays. Yet, we do not know how these judgments are made. Here, we use machine-learning algorithms to assess what factors predict similarity judgments and whether decision trees capture the judgment outcomes and process. We find that combining small and large values into numerical differences and ratios and arranging them in tree-like structures can predict both similarity judgments and response times. Our results suggest that we can use machine learning to not only model decision outcomes but also model how decisions are made. Revealing how people make these important judgments may be useful in developing interventions to help them make better decisions.     

On the prediction of confusion matrices from similarity judgments

Three observers viewed visual representations of eight complex sounds in both a pairwise similarity-judgment task and an identification task. A multidimensional scaling procedure applied to the similarity judgments yielded a three-dimensional perceptual space and the relative positions of the stimuli in that space. A probabilistic decision model based on weighted interstimulus distances served to predict well the confusion matrices of the identification task. Three conditions of the identification task, calling for identification of different subsets of the eight stimuli, led the observers to vary the weights they placed on the dimensions; they apparently adjusted the weights to maximize the percent correct identification. An additional group of 14 subjects, participating only in the similarity-judgment task, manifested the same three dimensions as the observers (corresponding to the locus of low-frequency energy, the locus of midfrequency energy, and visual contrast), and also a fourth dimension (corresponding to the periodicity, or waxing and waning, of the sound). Although not evident in the scaling analysis for the three observers, our utilization of the additional dimension increased significantly the variance accounted for in their identification responses. The overall accuracy of the predictions from a perceptual space to identification responses supplies a substantial validation of the use of multidimensional scaling procedures to reveal perceptual structure in demonstrating the ability of that structure to account for behavior in an independent task. The empirical success of this approach, furthermore, suggests a relatively simple and practical means of predicting, and possibly enhancing, identification performance for a given set of visual or auditory stimuli.     

Naloxone modulates visual judgments of similarity but not dissimilarity

Endogenous opioids have been implicated in mediating (placebo) analgesia, in reward processes, and in the regulation of socially relevant emotions. To explore their potential contributions to higher cognitive functions, we used a novel task with tachistoscopically presented (for 150 ms) pairs of meaningless figures. Healthy right-handed men judged the similarities and dissimilarities between the two figures on a visual analogue scale (VAS) in two separate runs. In a double-blind, between-subjects design, subjects were administered intravenously either 0.2-mg/kg naloxone or placebo 10 min prior to the task, and VAS judgments and response latencies were measured. We found a significant interaction between substance group and type of judgment: The magnitude of the similarity judgments was lower in the naloxone than in the placebo group, while dissimilarity judgments remained uninfluenced by the treatment. Reaction latencies and mood scores, assessed before and after substance administration, did not differ between the two groups, indicating that the findings did not rely on altered motor performance or motivation. We suggest that naloxone decreased the “similarity criterion” in comparative judgments, indicating its potentially modulatory effect on visual cognition. The task introduced here could be used for the implicit study and quantification of subtle affective–cognitive processes beyond the level of mere questionnaire data.     

Spatial attention is necessary for object-based attention: Evidence from temporal-order judgments

Attentional selection is a dynamic process that relies on multiple types of representations. That object representations contribute to attentional selection has been known for decades; however, most evidence for this contribution has been gleaned from studies that have relied on various forms of spatial cueing (some endogenous and some exogenous). It has thus remained unclear whether object-based attentional selection is a direct result of spatial cuing, or whether it still emerges without any spatial marker. Here we used a novel method—the temporal-order judgment (TOJ)—to examine whether object-based guidance emerges in the absence of spatial cuing. Participants were presented with two rectangles oriented either horizontally or vertically. Following a 150-ms preview time, two target stimuli were presented on the same or on different objects, and participants were asked to report which of the two stimuli had appeared first. The targets consisted of stimuli that formed a percept of a “hole” or a “hill.” First, we demonstrated that the “hill” target was indeed processed faster, as evidenced by a positive perceived simultaneity (PSS) measure. We then demonstrated that if two targets appeared with equal probabilities on the same and on different objects, the PSS values, although positive, were not modulated by the objects. In a subsequent set of experiments, we showed that objects can modulate attentional allocation—however, only when they are biased by a spatial (endogenous) cue. In other words, in the absence of a spatial cue or bias, object representations do not guide attentional selection. In addition to providing new constraints for theories of object-based attentional guidance, these experiments introduce a novel paradigm for measuring object-based attentional effects.     

Disentangling similarity judgments from pragmatic judgments: Response to Sloutsky and Fisher (2012)

Sloutsky and Fisher (2012) attempt to reframe the results presented in Noles and Gelman (2012) as a pure replication of their original work validating the similarity, induction, naming, and categorization (SINC) model. However, their critique fails to engage with the central findings reported in Noles and Gelman, and their reanalysis fails to examine the key comparison of theoretical interest. In addition to responding to the points raised in Sloutsky and Fisher's (2012) critique, we elaborate on the pragmatic factors and methodological flaws present in Sloutsky and Fisher (2004) that biased children's similarity judgments. Our careful replication of that study suggests that, rather than measuring the influence of labels on judgments of perceptual similarity, the original design measured sensitivity to the pragmatics of task demands. Together, the results reported in Noles and Gelman and the methodological problems highlighted here represent a serious challenge to the validity of the SINC model specifically and the words-as-features view more generally. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

An analysis of individual differences in similarity judgments about complex random forms

A variation of the method of graded dichotomies was used to obtain judgments of interstimulus similarity for all pairings of 21 12-turn random shapes. Using the Tucker-Messick procedure, a six-dimensional spatial model, representing individual variation in performance on the task, was derived. Six “idealized individuals” (IIs) were isolated. A five-dimensional Euclidean spatial model was obtained for each II using the Shepard-Kruskal scaling technique. The resulting psychological dimensions of perceived form were related to two sets of physical measures on the forms: the factor space suggested by Brown and Owen and a set of more basic physical measures. These basic measures allowed interpretation of most of the psychological dimensions and revealed differences between IIs in patterns of cue utilization.     

Role of structure and component in judgments of visual similarity of Chinese characters

Skilled readers of Chinese participated in sorting and visual search experiments. The sorting results showed that under conditions of conflicting information about structure and component, subjective judgments of the visual similarity among characters were based on the characters' overall configurations (i.e., structures) rather than on the common components the characters possessed. In visual search, both structure and component contributed to the visual similarity reflected by the search efficiency. The steepest search slopes (thus the most similar target-distractor pairs) were found when the target and the distractor characters had the same structure and shared 1 common component, compared with when they had different structures and/or shared no common components. Results demonstrated that character structure plays a greater role in the visual similarity of Chinese characters than has been considered.     

The role of similarity and dissimilarity focus in sequential judgments of physical attractiveness

The present results indicate that procedurally priming comparison focus can change the contrast effect in judgments of physical attractiveness (Kenrick & Gutierres, 1980). Participants were primed to search for similarities vs. differences between target and standard of comparison in a task using material irrelevant to the subsequent physical attractiveness judgment. Focusing participants on similarities testing produced the assimilation effect: evaluation of target and comparison standard as being similar. Focusing participants on dissimilarity testing produced the contrast effect: evaluating the target as different from the standard of comparison.