Functional equivalence between same-different classifications and judged similarity of Markov patterns

This experiment represented an initial at tempt at comparing same-different classifications and similarity judgments of Markov histoforms sampled from three different schema families. A measure of individual stimulus variability was more strongfy related to classification responses than to judged similarity. Dichotomous responses, derived from the similarity data by imposing threshold criteria, were found to be highly similor to real classification responses when the threshold values were estimated directly from the latter; little correspondence, however, was obtained using optimal classification criteria. The results support the notion that somewhat different features are used in making classification responses and similarity judgments, and indicate the need for developing more sensitive tasks involving controlled scanning of pattem information.     

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.     

The face in the crowd revisited: a threat advantage with schematic stimuli

Schematic threatening, friendly, and neutral faces were used to test the hypothesis that humans preferentially orient their attention toward threat. Using a visual search paradigm, participants searched for discrepant faces in matrices of otherwise identical faces. Across 5 experiments, results consistently showed faster and more accurate detection of threatening than friendly targets. The threat advantage was obvious regardless of whether the conditions favored parallel or serial search (i.e., involved neutral or emotional distractors), and it was valid for inverted faces. Threatening angry faces were more quickly and accurately detected than were other negative faces (sad or "scheming"), which suggests that the threat advantage can be attributed to threat rather than to the negative valence or the uniqueness of the target display.     

A multidimensional scaling analysis of judged similarity of complex forms from two task situations

Ss provided judgments of pairwise stimulus similarities for 21 12-turn random forms in two experimental tasks: a scaling task, involving a variant of the method of graded dichotomies, and a sorting task, which simply required Ss to categorize the forms. The grouped data from both tasks, when analyzed using nonmetric multidimensional scaling techniques, yielded five-dimensional configurations with euclidean distances. The correspondence of these two spaces, assessed using canonical correlations, was extremely good. The psychological dimensions derived from both tasks 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. Physical cues of greatest importance involved size, dispersion, angularity, and rotation measures. The value of the tasks and the utility of the Brown and Owen measures were discussed.     

Absolute and relative effects of similarity and distance on grouping

Four experiments are reported, the aim of which was to explore the achromatic-colour and distance relations that determine the probability of achromatic surfaces grouping perceptually. The first two experiments were performed to test Wertheimer's conjecture that similarity and dissimilarity of achromatic colours jointly determine grouping. The results indicate that only similarity of achromatic colours determines grouping. Data from the other two experiments show that grouping is determined by absolute, relative, and Gillam's distances. These findings agree with previous literature showing that different algorithms or mechanisms determine grouping by similarity and grouping by distance. Additionally, these findings show that the single factor of grouping by distance also depends on multiple algorithms or mechanisms.     

Representation over time: the effects of temporal distance on similarity

Similarity is central in human cognition, playing a role in a wide range of cognitive processes. In three studies, we demonstrate that subjective similarity may change as a function of temporal distance, with some events seeming more similar when considered in the near future, while others increase in similarity as temporal distance increases. Given the ubiquity of inter-temporal thought, and the fundamental role of similarity, these results have important implications for cognition in general.     

Dimensional,similarity, and configurai classification of integral and separable stimuli

Subjects classified sets of two-dimensional stimuli into two or three groups in any way they wished. For integral stimuli, classification was based on numerical balance and the similarity structure. For separable stimuli, classification was based on the dimensional structure and the configurai properties of the stimulus set. These results replicate and extend those of Handel and Imai (1972). In addition, they suggest that no closed set of stimulus concepts is possible.     

Relation between judged and physical distance in multicue conditions as a function of instructions and tasks.

Using a rod adjustable in distance 48 Os produced equal depth intervals along a floor of a visual alley (interval reproduction) or bisected a given depth interval into two equal parts (bisection). Also, verbal reports were obtained of a depth interval located at a near and farther distance from O (absolute judgments). Two kinds of instructions, "apparent" and "objective," were used with different Os with each of the three tasks. There was an over-all tendency (p = .05 on two of three tasks) for apparent instructions to produce less over-constancy or more under-constancy of distance than that produced by objective instructions. This tendency is consistent with a cognitive interpretation of over-constancy of distance. Clear over-constancy was obtained only by the combination of objective instructions and the bisection task. Clear under-constancy was obtained only by the combination of apparent instructions and the method of absolute judgments. The reason for the effect of task on magnitude of distance constancy is not understood.     

Effect of the similarity between target and global and local levels in hierarchical stimuli processing

The hypothesis of global precedence was investigated by manipulating the similarity between target and relevant level, and between target and global and local levels of hierarchical stimuli, both in divided and selective attention conditions. The similarity was measured on the basis of the amount of shared contour between two visual forms. The stimuli were circles, right-facing semicircles, i.e., 1/2 of the circumference missing, and right-facing partial circles with a 1/4 of the circumference missing. The circle was used as a target and, consequently, the similarity between target and semicircle and between it and the partial circle was 50% and 75%, respectively. In the divided attention condition, the results showed a local advantage in the two similarity conditions between target and distractor level (50% and 75%) and a bidirectional and symmetrical interference at both levels of similarity. However, in the 'selective attention condition', a local reaction time advantage was only found when the similarity between target and irrelevant level was of 50%. When attention was directed towards the global level, local interference increased depending on the decrease in the degree of the local level similarity. When the attention was directed towards the local level, there was global interference but it was independent of the degree of the global level similarity. These results show the importance of the physical shape of the local elements used in experiments with hierarchical stimuli, since they may determine the relative speed of global processing, facilitating or impairing it.     

Similar as well as dissimilar contextual stimuli increase rated similarity

Contextual stimuli from one category increase the rated similarity of stimuli from a second category. In Experiment 1, associates of one of the members of pairs of target words increased the rated similarity of the members slightly more than did much less similar contextual stimuli. In Experiment 2, contextual category names and good exemplars increased the rated similarity of pairs of poor to medium target exemplars and were also rated as more similar to these targets than the targets were to each other. In both cases, the category names resulted in the stronger effect. This ability of contextually similar stimuli to increase rated similarity opposes the distance-density and averaging-judgmental theories of the effect of context on similarity. However, the theory that a positive association exists between the perceived similarity of stimuli and the strength of the category to which they belong explains how both contextually dissimilar and contextually similar stimuli can increase rated similarity.     

Apparent distance in a horizontal plane with tactile-kinesthetic stimuli

In the study of active tactile-kinesthetic space perception apparent distance has been found to vary as a function of the direction of the line segment in a horizontal plane. The present data indicate that the error is not consistently related to the same frame of reference as the visual illusion. Rather, with movement of the extended arm to determine the relative distances between pairs of points, radial distances are overestimated in relation to tangential ones, whether parallel or perpendicular to the medial plane. Interpretations are in terms of kinesthetic stimulus patterns and the structure of perceptual representation.     

WINDSOR: Windsor improved norms of distance and similarity of representations of semantics

Lexical co-occurrence models of semantic memory form representations of the meaning of a word on the basis of the number of times that pairs of words occur near one another in a large body of text. These models offer a distinct advantage over models that require the collection of a large number of judgments from human subjects, since the construction of the representations can be completely automated. Unfortunately, word frequency, a well-known predictor of reaction time in several cognitive tasks, has a strong effect on the co-occurrence counts in a corpus. Two words with high frequency are more likely to occur together purely by chance than are two words that occur very infrequently. In this article, we examine a modification of a successful method for constructing semantic representations from lexical co-occurrence. We show that our new method eliminates the influence of frequency, while still capturing the semantic characteristics of words.     

The effect of similarity between elemental stimuli and compounds in olfactory patterning discriminations

We studied the ability of honeybees to discriminate between single odorants and binary olfactory mixtures. We analyzed the effect of the number of common elements between these two stimulus classes on olfactory discrimination. We used olfactory conditioning of the honeybees' proboscis extension reflex (PER), a paradigm in which odors can be associated with a reinforcement of sucrose solution. Bees were asked to discriminate reinforced from nonreinforced olfactory stimuli. They were trained with two elemental odors (A and B) versus a binary olfactory mixture. The mixture was either AB (group 2CE, two common elements), AC (group 1CE, one common element A), or CD (group 0CE, no common element). Three groups followed a positive patterning schedule (mixture reinforced and elements nonreinforced: groups 2CE+, 1CE+, and 0CE+) and three other groups a negative patterning schedule (mixture nonreinforced and elements reinforced: groups 2CE-, 1CE-, and 0CE-). We showed that a reduction of similarity (number of common elements) between elemental odors and compounds enhanced the ability to discriminate elements from compounds and that the kind of compound processing used by the bees supports theories that assume nonelemental compound processing (i.e., that exclude the mere summation of the elemental associative strengths upon compound presentation).     

Content and distance similarity models: a correction to Sjöberg

Corrections are made to a statement by Sjöberg (1977) concerning the compatibility of results obtained by him and by Gregson (1976).