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.     

Overprediction and blocking in the McCollough aftereffect

The Rescorla-Wagner theory (Rescorla & Wagner, 1972) of associative learning offers specific predictions about the associative strength of CS-US pairs when two or more CSs are conditioned to the same US separately and subsequently paired in a compound with the same US. The magnitude of orientation-contingent color aftereffects (AEs) was used as an index of associative strength in this study. The results of experiments using an "overprediction" (Rescorla, 1970) and a "blocking" (Kamin, 1969) paradigm conformed to the predictions of the Rescorla-Wagner theory. In Experiment 1, AEs were established simultaneously for horizontal-vertical and diagonal patterns. When observers subsequently viewed compound induction patterns, AE magnitude was found to be significantly decreased, relative to a condition in which observers did not view such an induction pattern. In Experiment 2, AE magnitude for a given test pattern following inspection of compound induction stimuli was significantly reduced by inspection of the other component prior to viewing the compound induction stimuli. The applicability of associative learning and feature-adaptation models of the McCollough effect is discussed.     

Personality and Olfactory Sensitivity

Even though perceptional abilities have repeatedly been found to be associated with certain personality styles (e.g., extraversion), such connections were reported sparsely for the olfactory modality. Two studies were carried out to investigate the relationship between olfactory sensitivity and 12 personality dimensions (including extraversion and neuroticism). In the first study, single olfactory measurements were compared to repeated measurements. In the second study, twins were recruited as subjects to also examine the heredity of olfactory sensitivity. The results indicate that neuroticism is a stronger predictor for olfactory sensitivity than extraversion. Repeated measurements seem to be necessary to obtain valid data on olfactory performance.     

Categorization of visual stimuli in the honeybee Apis mellifera

Categorization refers to the classification of perceptual input into defined functional groups. We present and discuss evidence suggesting that stimulus categorization can also be found in an invertebrate, the honeybee Apis mellifera, thus underlining the generality across species of this cognitive process. Honeybees show positive transfer of appropriate responding from a trained to a novel set of visual stimuli. Such a transfer was demonstrated for specific isolated features such as symmetry or orientation, but also for assemblies (layouts) of features. Although transfer from training to novel stimuli can be achieved by stimulus generalization of the training stimuli, most of these transfer tests involved clearly distinguishable stimuli for which generalization would be reduced. Though in most cases specific experimental controls such as stimulus balance and discriminability are still required, it seems appropriate to characterize the performance of honeybees as reflecting categorization. Further experiments should address the issue of which categorization theory accounts better for the visual performances of honeybees.This contribution is part of the special issue “Animal Logics” (Watanabe and Huber 2006).     

Olfactory adaptation and recovery in old age

Four experiments are reported in which it is shown that elderly adults are more prone than young adults to olfactory adaptation and are slower to recover threshold sensitivity. The first three experiments differed in detail, but had in common an initial threshold determination for 1-butanol, a 30 s exposure to a concentration twenty-seven times threshold, followed by repeated presentation of the initial threshold level at various intervals after adaptation. In three experiments accuracy of forced-choice discrimination was poor immediately after adaptation but tended to improve with time, and considerably faster in the young than in the elderly. In the fourth experiment, groups of twenty-three elderly and twenty-five young subjects threshold-matched for pyridine were compared. The subjects participated in three sessions in which pyridine was infused into a test chamber at either 2.5, 1.25, or 0 L min-1 (sham session). At 2.5 L min-1 both groups were able to track the buildup of odor intensity during infusion and its decline after infusion. In contrast, at 1.25 L min-1 only the young were able to track odor intensity, even though the concentration rose above initial threshold levels.     

Transformation and alignment in similarity

This paper contrasts two structural accounts of psychological similarity: structural alignment (SA) and Representational Distortion (RD). SA proposes that similarity is determined by how readily the structures of two objects can be brought into alignment; RD measures similarity by the complexity of the transformation that “distorts” one representation into the other. We assess RD by defining a simple coding scheme of psychological transformations for the experimental materials. In two experiments, this “concrete” version of RD provides compelling fits of the data and compares favourably with SA. Finally, stepping back from particular models, we argue that perceptual theory suggests that transformations and alignment processes should generally be viewed as complementary, in contrast to the current distinction in the literature.     

Modulating the phonological similarity effect: The contribution of interlist similarity and lexicality

The classical phonological similarity effect (PSE) was studied with words and nonwords in two immediate serial recall (ISR) tasks. The relative contributions of intralist and interlist interference were compared, and differential effects on item and order memory were observed. PSE occurred with words and was reversed with nonwords. In addition, PSE was modulated by interlist similarity, which enhanced recall of rhyme items and impaired recall of distinct items. Finally, interlist similarity reduced item recall of words, whereas it improved serial recall of nonwords. The latter finding rules out the hypothesis that the reverse PSE for nonwords is due to interlist interference. It is concluded that two opposing effects of phonological intralist similarity cause the interaction between PSE and lexicality in ISR. With words, the positive effect on item recall is usually masked by a much more disruptive effect on position accuracy. With nonwords, however, the positive effect often masks the negative one. These findings are discussed in relation to current models of verbal short-term memory.     

Identity and similarity

The standard approach to the so-called paradoxes of identity has been to argue that these paradoxes do not essentially concern the notion of identity but rather betray misconceptions on our part regarding other metaphysical notions, like that of an object or a property. This paper proposes a different approach by pointing to an ambiguity in the identity predicate and arguing that the concept of identity that figures in many ordinary identity claims, including those that appear in the paradoxes, is not the traditional philosophical concept but one that can be defined in terms of relevant similarity. This approach to the paradoxes will be argued to be superior to the standard one.     

Cognitive architecture of a mini-brain: the honeybee

Honeybees have small brains, but their behavioural repertoire is impressive. In this article we focus on the extent to which adaptive behaviour in honeybees exceeds elementary forms of learning. We use the concept of modularity of cognitive functions to characterize levels of complexity in the honeybee brain. We show that behavioural complexity in the honeybee cannot be explained by independent functions of vertically arranged, domain-specific processing modules, but requires horizontal integration in a central state, and we identify neural mechanisms that may underlie domain-specific processing and central integration. The honeybee may serve as a useful model for the study of intermediate levels of complexity in cognitive functions and the search for their neural substrates.     

Belief similarity and attitude similarity as determinants of interpersonal attraction

It was predicted that attraction would be a function of both attitude similarity and belief similarity, but that attitude similarity would have the greater influence. In Expt I, 60 subjects were presented with strangers that were either similar or dissimilar on attitude and on belief. Attraction was a positive function of both attitude similarity (p < .05) and belief similarity (p < .01). Experiment II replicated and extended Expt I with the addition of a 50% similar group for both attitude and belief. Attraction was a positive linear function of both attitude similarity (p < .001) and belief similarity (p < .02); departure from linearity was not significant. Attitude similarity also had greater effects on other aspects of interpersonal evaluation than belief similarity. The results were discussed in terms of the locus of reinforcement of attitude similarity and of belief similarity.     

Olfactory self-recognition in a cichlid fish

Animal self-cognizance might be of importance in different contexts like territoriality, self-referent mate-choice or kin recognition. We investigated whether the cichlid fish Pelvicachromis taeniatus is able to recognize own olfactory cues. P. taeniatus is a cave breeding fish with pronounced brood care and social behavior. In the experiments we gave male cave owners the choice between two caves in which we introduced scented water. In a first experiment males preferred caves with their own odor over caves with the odor of an unfamiliar, unrelated male. To examine whether self-recognition is based rather on individual or on family cues we conducted two further experiments in which males could choose between their own odor and the odor of a familiar brother and between the odor of a familiar brother and an unfamiliar, unrelated male, respectively. Males preferred their own odor over that of a familiar brother suggesting individual self-referencing. Interestingly, males (at least outbred ones) preferred the odor of an unfamiliar, unrelated male over that of a familiar brother, maybe to avoid competition with kin. We discuss the results in the context of animal self-cognizance. All experiments were conducted with in- and outbred fish. Inbreeding did not negatively affect self-recognition.