Visual categorization of natural stimuli by domestic dogs

One of the fundamental issues in the study of animal cognition concerns categorization. Although domestic dogs (Canis familiaris) are on the brink to become one of the model animals in animal psychology, their categorization abilities are unknown. This is probably largely due to the absence of an adequate method for testing dogs’ ability to discriminate between large sets of pictures in the absence of human cueing. Here we present a computer-automated touch-screen testing procedure, which enabled us to test visual discrimination in dogs while social cueing was ruled out. Using a simultaneous discrimination procedure, we first trained dogs (N = 4) to differentiate between a set of dog pictures (N = 40) and an equally large set of landscape pictures. All subjects learned to discriminate between the two sets and showed successful transfer to novel pictures. Interestingly, presentation of pictures providing contradictive information (novel dog pictures mounted on familiar landscape pictures) did not disrupt performance, which suggests that the dogs made use of a category-based response rule with classification being coupled to category-relevant features (of the dog) rather than to item-specific features (of the background). We conclude that dogs are able to classify photographs of natural stimuli by means of a perceptual response rule using a newly established touch-screen procedure. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Subtle activation of a social categorization triggers group-level emotions

Previous research [Smith, E. R., Seger, C. R., & Mackie, D. M. (2007). Can emotions be truly group-level? Evidence regarding four conceptual criteria. Journal of Personality and Social Psychology, 93, 431-446] has demonstrated that when people are explicitly asked about the emotions they experience as members of a particular group, their reported emotions converge toward a profile typical for that group. Two studies demonstrate that the same type of convergence occurs when a group identity is made situationally salient through priming, without an explicit request to report group-level emotions. People who identify more strongly with the group converge more, and show more similarity between their group-primed emotions and explicitly reported group-level emotions. This research confirms that activating a social identity produces convergence for emotions as well as for attitudes and behaviors. It also suggests that some previous emotion research may have tapped group rather than individual-level emotions, potentially requiring some reconceptualization.     

Effects of divided attention and social categorization on the own-race bias in face recognition

Perceivers remember own-race faces more accurately than other-race faces (i.e., Own-Race Bias). In the current experiments, we manipulated participants' attentional resources and social group membership to explore their influence on own and other-race face recognition memory. In Experiment 1, Chinese participants viewed own-race and Caucasian faces, and between-subjects we manipulated whether participants attention was divided during face encoding. We found that divided attention eliminated the Own-Race Bias in memory due to a reduction of memory accuracy for own-race faces, implicating that attention allocation plays a role in creating the bias. In Experiment 2, Chinese participants completed an ostensible personality test. Some participants were informed that their personality traits were most commonly found in Caucasian (i.e., other-race) individuals, resulting in these participants sharing a group membership with other-race targets. In contrast, other participants were not told anything about the personality test, resulting in the default own-race group membership. The participants encoded the faces for a subsequent recognition memory test either with or without performing a concurrent arithmetic distracting task. Results showed that other-race group membership and reducing attention during encoding independently eliminated the typical Own-Race Bias in face memory. The implications of these findings on perceptual-expertise and social-categorization models are discussed.     

Effects of stimulus duration and choice delay on visual categorization in pigeons

We [Lazareva, O. F., Freiburger, K. L., & Wasserman, E. A. (2004). Pigeons concurrently categorize photographs at both basic and superordinate levels. Psychonomic Bulletin and Review, 11, 1111-1117] previously trained four pigeons to classify color photographs into their basic-level categories (cars, chairs, flowers, or people) or into their superordinate-level categories (natural or artificial). Here, we found that brief stimulus durations had the most detrimental effect on the basic-level discrimination of natural stimuli by the same pigeons. Increasing the delay between stimulus presentation and choice responding had greater detrimental effect on the basic-level discrimination than the superordinate-level discrimination. These results suggest that basic-level discriminations required longer stimulus durations and were more subject to forgetting than were superordinate-level discriminations. Additionally, categorization of natural stimuli required longer stimulus durations than categorization of artificial stimuli, but only at the basic level. Together, these findings suggest that basic-level categorization may not always be superior to superordinate-level categorization and provide additional evidence of a dissociation between natural and artificial stimuli in pigeons’ categorization.     

Thought about actions in social domains: Morality,social conventions,and social interactions

Judgments about actual and hypothetical events were examined. The study, conducted in elementary (first, third, and fifth grades) and junior high (seventh grades) schools, included behavioral observations and assessments of judgments. Observations were conducted of 108 events classified as moral, as conventional, and as mixed type. Participants’ reactions and communications differed by domain of the event. Judgments and justifications of 312 participants in the events showed that they discriminated between the domains on several dimensions. Judgments and justifications corresponded with ones made about comparable hypothetical situations. The study supported the proposition that judgments in the domains of morality and social convention about actual events correspond with judgments about hypothetical situations. It was also found that the domains are associated with the ways children interact socially.     

社会分类的特性,维度及心理效应

社会分类是个体基于共享相似性将人群分为不同类别的一种主观心理过程, 具有自动化,灵活性和潜在模糊性等特性.社会分类的维度既包括性别,年龄和种族等自然线索, 也包括语言,职业和社会身份等重要社会线索.在社会分类过程中, 不同维度往往具有相对重要性, 表现为优势维度效应; 不同维度相互之间也会发生作用, 产生交叉分类效应, 研究者从不同的视角对这种交叉分类效应进行了解释.未来研究应该采用多样化的方法和技术从分类主体,分类目标,分类情境以及社会文化因素等多角度探讨社会分类的心理加工机制, 构建更具整合性的社会分类理论模型.     

Resource-dependent effects during sex categorization

The limited capacity of face perception resources in the left cerebral hemisphere was examined using a sex categorization task. One study tested the hypothesis that sex categorization is impeded whenever feature extraction resources in the left hemisphere are simultaneously being utilized by another task. This hypothesis was tested by presenting prime faces for either 32 ms or 320 ms to either the left or right visual-field just before centrally presented target faces were categorized by sex. Results showed that sex categorization was slower after prime faces were presented for 32 ms in the right visual-field compared to the left visual-field. This difference was not found after the 320 ms prime length. The results are interpreted in the context of a neurocognitive model of social perception and suggest that efficient sex categorization depends, in part, on the availability of facial feature extraction resources in the left hemisphere.     

The importance of feature distribution and correlation for simulating 3 to 4-month-old infants' visual categorization processes

Mareschal, French, and Quinn (2000) and Mareschal, Quinn, and French (2002) have proposed a connectionist model of visual categorization in 3- to 4-month-old infants that simulates and predicts previously unexplained behavioural effects such as the asymmetric categorization effect (French, Mareschal, Mermillod, & Quinn, 2004). In the current paper, we show that the model's ability to simulate the asymmetry depends on the correlational structure of the stimuli. These results are important given that adults (Anderson & Fincham, 1996) as well as infants (Younger & Cohen, 1986) are able to rely on correlation information to perform visual categorization. At a behavioural level, the current paper suggests that pure bottom-up processes, based on the correlational structure of the categories, could explain the disappearance of the asymmetry in older 10-month-old infants (Furrer & Younger, 2005). Moreover, our results also raise new challenges for visual categorization models that attempt to simulate the shift from asymmetric categorization in 3- to 4-month-old to symmetric categorization in 10-month-old infants (Shultz & Cohen, 2004; Westermann & Mareschal, 2004, 2012).     

Influence of warmth and competence on the promotion of safe in-group selection: Stereotype content model and social categorization of faces

Categorizing an individual as a friend or foe plays a pivotal role in navigating the social world. According to the stereotype content model (SCM), social perception relies on two fundamental dimensions, warmth and competence, which allow us to process the intentions of others and their ability to enact those intentions, respectively. Social cognition research indicates that, in categorization tasks, people tend to classify other individuals as more likely to belong to the out-group than the in-group (in-group overexclusion effect, IOE) when lacking diagnostic information, probably with the aim of protecting in-group integrity. Here, we explored the role of warmth and competence in group-membership decisions by testing 62 participants in a social-categorization task consisting of 150 neutral faces. We assessed whether (a) warmth and competence ratings could predict the in-group/out-group categorization, and (b) the reliance on these two dimensions differed in low-IOE versus high-IOE participants. Data showed that high ratings of warmth and competence were necessary to categorize a face as in-group. Moreover, while low-IOE participants relied on warmth, high-IOE participants relied on competence. This finding suggests that the proneness to include/exclude unknown identities in/from one's own in-group is related to individual differences in the reliance on SCM social dimensions. Furthermore, the primacy of the warmth effect seems not to represent a universal phenomenon adopted in the context of social evaluation.     

The relationship between anti-gay prejudice and the categorization of sexual orientation

A relatively large literature has demonstrated that sexual orientation can be judged accurately from a variety of minimal cues, including facial appearance. Untested in this work, however, is the influence that individual differences in prejudice against gays and lesbians may exert upon perceivers’ judgments. Here, we report the results of a meta-analysis of 23 unpublished studies testing the relationship between anti-gay bias and the categorization of sexual orientation from faces. Aggregating data from multiple measures of bias using a variety of methods in three different countries over a period of 8 years, we found a small but significant negative relationship between accuracy and prejudice that was homogeneous across the samples tested. Thus, individuals reporting higher levels of anti-gay bias appear to be less accurate judges of sexual orientation.     

The role of social categorization and identity threat in the perception of migrants

This paper investigates how the categorization of migrant workers shapes their reception. In an experiment with Northern Irish Protestants we manipulated the representation of Poland to make the Catholicism of Polish migrants either more, or less, salient. Furthermore, judgements of Polish migrants were obtained under conditions designed to encourage participants to believe that sectarian conflict in Northern Ireland was either resolved, or still a strong feature of the present social landscape. Overall, results showed that when Poland's Catholicism was salient, participants were less welcoming of Polish migrants. Furthermore, this effect was mediated by increases in the level of symbolic threat participants believed the migrants posed to participants' (Protestant) community identity. Copyright © 2009 John Wiley & Sons, Ltd.     

Examining differences in minority versus majority preschoolers on social categorization and perceived intergroup distance

We examined the differences between majority and minority children (i.e., group membership) on racial categorization and perceived cultural distance, among 4‐ to 6‐year‐old children, in low diversified schools. We used a spontaneous social categorization task using pictures of children from three different racial groups broadly represented in France (Europeans, Black‐, and North‐Africans), and an evaluation of the perceived cultural distance between participants' in‐group and the racial group represented in the picture, adapted to children and based on three factors (language, eating habits, and music). Results revealed an effect of age on racial categorization: the older the children, the more successful they are in this task. They showed a significant effect of the racial group represented in the photos on perceived cultural distance: members of minority groups (i.e., Black‐ and North‐Africans) were evaluated as more different compared to those of the majority group on each of the factors. Finally, we got an interaction between participants' in‐group and the racial group represented in the pictures, for the language factor: members of the majority group perceived as more different photographs representing minorities peers than those representing majority peers, while participants belonging to minority groups perceived no differences between photographs, according to the racial criteria.     

Contextual control of stimulus generalization and stimulus equivalence in hierarchical categorization

The purpose of this study was to determine whether hierarchical categorization would result from a combination of contextually controlled conditional discrimination training, stimulus generalization, and stimulus equivalence. First, differential selection responses to a specific stimulus feature were brought under contextual control. This contextual control was hierarchical in that stimuli at the top of the hierarchy all evoked one response, whereas those at the bottom each evoked different responses. The evocative functions of these stimuli generalized in predictable ways along a dimension of physical similarity. Then, these functions were indirectly acquired by a set of nonsense syllables that were related via transitivity relations to the originally trained stimuli. These nonsense syllables effectively served as names for the different stimulus classes within each level of the hierarchy.     

The social face of emotion recognition: Evaluations versus stereotypes

The goal of the present paper was to demonstrate the influence of general evaluations and stereotype associations on emotion recognition. Earlier research has shown that evaluative connotations between social category members and emotional expression predict whether recognition of positive or negative emotional expressions will be facilitated (e.g. Hugenberg, 2005). In the current paper we tested the hypothesis that stereotype associations influence emotion recognition processes, especially when the difference between valences of emotional expressions does not come into play. In line with this notion, when participants in the present two studies were asked to classify positive versus negative emotional expressions (i.e. happy versus anger, or happy versus sadness), valence congruency effects were found. Importantly, however, in a comparative context without differences in valence in which participants were asked to classify two distinct negative emotions (i.e. anger versus sadness) we found that recognition facilitation occurred for stereotypically associated discrete emotional expressions. With this, the current results indicate that a distinction between general evaluative and cognitive routes can be made in emotion recognition processes.     

Familiarity effects on categorization levels of faces and objects

It is well established that faces, in contrast to objects, are categorized as fast or faster at the individual level (e.g., Bill Clinton) than at the basic-level (e.g., human face). This subordinate-shift from basic-level categorization has been considered an outcome of visual expertise with processing faces. However, in the present study we found that, similar to familiar faces, categorization of individually-known familiar towers is also faster at the individual level than at the basic-level in naïve participants. In addition, category-verification of familiar stimuli, at basic and superordinate levels, was slower and less accurate compared to unfamiliar stimuli. Thus, the existence of detailed semantic information, regardless of expertise, can induce a shift in the default level of object categorization from basic to individual level. Moreover, the individually-specific knowledge is not only more easily-retrieved from memory but it might also interfere with accessing more general category information.     

The role of functional information for infant categorization

This report examines whether knowledge about function influences the formation of artifact categories in 11-12- month old infants. Using an object-examination task, a set of artificial stimuli was presented that could either be grouped according to overall similarity or according to similarity in one functionally relevant part. Experiment 1 revealed that infants categorized the objects according to overall similarity but not part similarity under control conditions. Experiment 2 showed that after having seen the experimenter demonstrating the functional use of the critical part, infants later categorized the stimuli according to part similarity. When the same actions were performed without producing any effect, infants failed to categorize according to the critical part. This set of findings suggests that 11-12-month old infants use functional information as a cue to categorization.     

Representations and social knowledge: An integrative effort through a normative structural perspective

The structural approach on social representations is known for the development of central core theory and its similarity with cognition-oriented sociopsychological perspectives, which has been a target of criticism. The approach has difficulty in dealing with the social dimension of knowledge and adopts a static notion of structure. Acknowledging those shortcomings, we present a revised structural conceptual model of social knowledge and social representations based on the consideration of normative and social identity processes, compatible with contributions of authors external to the classical structural approach, such as Wagner (holomorphy) and Lahlou (propagation model). After redefining the concepts of cognem and structure, we tackle thinking processes and the differences between personal and social representations, conceiving the latter as conventional codes linked to groups. Limitations of the perspective are discussed and research directions are indicated based on an understanding of structure that is broader than the one adopted by the classical approach.     

Modelling individual difference in visual categorization

Recent years has seen growing interest in understanding, characterizing, and explaining individual differences in visual cognition. We focus here on individual differences in visual categorization. Categorization is the fundamental visual ability to group different objects together as the same kind of thing. Research on visual categorization and category learning has been significantly informed by computational modelling, so our review will focus both on how formal models of visual categorization have captured individual differences and how individual difference have informed the development of formal models. We first examine the potential sources of individual differences in leading models of visual categorization, providing a brief review of a range of different models. We then describe several examples of how computational models have captured individual differences in visual categorization. This review also provides a bit of an historical perspective, starting with models that predicted no individual differences, to those that captured group differences, to those that predict true individual differences, and to more recent hierarchical approaches that can simultaneously capture both group and individual differences in visual categorization. Via this selective review, we see how considerations of individual differences can lead to important theoretical insights into how people visually categorize objects in the world around them. We also consider new directions for work examining individual differences in visual categorization.     

Evidence for task-dependent categorization in infancy

Two experiments compared infants' attention to the categorical distinction between people and animals in object-examining and sequential-touching tasks. In Experiment 1, 10- and 13-month-old infants distinguished between animals and people in an object-examining task. In this task, infants are familiarized with individual exemplars from one category, and then their response to exemplars from another category is measured. In Experiment 2, 13- and 16-month-old infants, but not 10-month-old infants, attended to the same distinction in a sequential-touching task. In this task, infants are presented with several exemplars from two categories simultaneously, and the order in which they touch those objects is assessed. Evaluation of infants' touching behavior in Experiment 2 also revealed developmental changes in how they approached this task. The combined results of these two experiments confirm the general trend reported in the literature and begin to provide insight into developmental changes that contribute to infants' ability to apply their categorization skills in different task contexts.     

Victim’s innocence, social categorization, and the threat to the belief in a just world

This research studies people’s reactions to the suffering of victims, examining the hypothesis of the belief in a just world (BJW) (Lerner, 1980) according to which the awareness of innocent victims threatens people’s BJW, and extending the scope of BJW theory to intergroup contexts. An implicit measure of the threat to the BJW (Hafer, 2000a) is used in this research. After participants viewed a videotaped film containing the victimization story they performed an emotional modified Stroop task. Study 1 examined the threat to the BJW as function of the innocence of the victim at an interpersonal level of analysis. Results show that only the innocent victim threatens the observer’s BJW. Study 2 examined the threat to the BJW as function of the victim’s group and of the victim’s innocence. Results show that an ingroup victim threatens the participant’s BJW more than a victim belonging to an outgroup.