Categorization by groups and individuals

Categorization is a core psychological process that is central to decision making. While a substantial amount of research has been conducted to examine individual categorization behavior, little is known about how the outputs of individual and group categorization may differ. Four experiments demonstrate that group categorization differs systematically from individual categorization in the structural dimension of category breadth: categorizing the same set of items, groups tend to create a larger number of smaller categories than individuals. This effect of social context is a function of both taskwork and teamwork. In terms of taskwork, groups’ greater available knowledge mediates differences in category breadth between individuals and groups by increasing utilized knowledge (study 2). In terms of teamwork, task conflict moderates the effect of social context on category breadth (study 3). Moreover, the experience of categorizing individually or in a group influences individuals’ subsequent judgments (study 4).     

Unsupervised categorization with a child sample: category cohesion development

Studies into categorization have demonstrated that the ability to form concepts is an essential ability in cognitive development. For example, before a decision about anything can be made, firstly category concepts need to be acquired in order to make efficient decisions about that situation. The present study explored a particular type of category learning, not previously explored in this particular context – unsupervised categorization with 16 items and two dimensions, and comparing specifically children vs. adults. Previous studies have typically focused on simpler designs such as three items of two dimensions in the triad tasks, or a greater number of dimensions but with much fewer items per category in other unsupervised settings. This study investigated unsupervised categorization with two levels of task difficulty, and compared two different populations, children and adults. The findings revealed that adults performed better for the easy condition but there was no difference between these groups for the more difficult category task. The findings also revealed that unsupervised categorization in more complex settings result in more one dimensional sorting, for both children and adults. The results are discussed in the context of unsupervised categorization development abilities in children.     

Transitive inference in pigeons: Control for differential value transfer

Transitive inference (TI) effects have been demonstrated in several nonhuman species using a nonverbal version of the task in which A is better than B is represented in a simple simultaneous discrimination, A+B?. Following five-term training (e.g., A+B?, B+C?, C+D?, D+E?), the choice of B over D on test trials is taken as evidence of TI. Recently, differential value transfer from the S+ to the S? in a simultaneous discrimination has been proposed as a noncognitive basis for these effects. Two experiments were conducted to control for differential value transfer. The results suggest that differential value transfer is not the only basis for nonhuman TI performance. An alternative account based on spatial mapping is discussed.     

Generalization hypothesis of abstract-concept learning: learning strategies and related issues in Macaca mulatta, Cebus apella, and Columba livia

The generalization hypothesis of abstract-concept learning was tested with a meta-analysis of rhesus monkeys (Macaca mulatta), capuchin monkeys (Cebus apella), and pigeons (Columba livia) learning a same/different (S/D) task with expanding training sets. The generalization hypothesis states that as the number of training items increases, generalization from the training pairs will increase and could explain the subjects' accurate novel-stimulus transfer. By contrast, concept learning is learning the relationship between each pair of items; with more training items subjects learn more exemplars of the rule and transfer better. Having to learn the stimulus pairs (the generalization hypothesis) would require more training as the set size increases, whereas learning the concept might require less training because subjects would be learning an abstract rule. The results strongly support concept or rule learning despite severely relaxing the generalization-hypothesis parameters. Thus, generalization was not a factor in the transfer from these experiments, adding to the evidence that these subjects were learning the S/D abstract concept.     

Encoding and retrieval processes in the memory for conceptually distinctive events

Memory for conceptually isolated (distinctive) words was investigated in two experiments. In Experiment 1, recognition of distinctive targets was compared with recognition of targets from homogeneous lists and with recognition of background information. Distinctive targets were better recognized than the same words presented in homogeneous lists. No effects of distinctiveness on the recognition accuracy of background items were observed. These results fail to support the hypothesis that distinctive information receives extra resources during encoding at the expense of surrounding background information. In Experiment 2 the effects of distinctiveness on recall were evaluated. Distinctive targets were more likely to be recalled than targets from homogeneous lists. However, unlike the effects found in recognition, background items were more poorly recalled from lists containing distinctive targets than from homogeneous lists. Organizational processes in recall were also evaluated. There was greater subjective organization for target and background items from lists containing distinctive targets than from lists containing nondistinctive targets. These results were discussed in terms of encoding and retrieval explanations of the effects of distinctiveness.     

Categorization in compulsive hoarding

Based on hypothesizing about the role of information processing, and in particular, underinclusive categorization in compulsive hoarding, this study examined categorization processes in people with clinically significant compulsive hoarding problems. Twenty-one participants with primary compulsive hoarding, 21 with OCD without hoarding, and 21 non-psychiatric controls completed three categorization tasks. Hoarding and OCD participants reported significantly more distress prior to each of the three tasks than did controls. On tasks sorting common household items, the groups did not differ on the number of piles created nor on the amount of time taken to sort. However, on a task sorting personally relevant items, hoarding participants took more time, created more piles, and reported more anxiety than non-psychiatric controls. Hoarders also took more time than the OCD group, and tended to create more piles. Hoarding severity was correlated with the number of piles created, but only when the objects were personally relevant. Results support under-inclusive categorizing for people with compulsive hoarding, but the effect was largely confined to objects of personal relevance.     

Causal status as a determinant of feature centrality

One of the major problems in categorization research is the lack of systematic ways of constraining feature weights. We propose one method of operationalizing feature centrality, a causal status hypothesis which states that a cause feature is judged to be more central than its effect feature in categorization. In Experiment 1, participants learned a novel category with three characteristic features that were causally related into a single causal chain and judged the likelihood that new objects belong to the category. Likelihood ratings for items missing the most fundamental cause were lower than those for items missing the intermediate cause, which in turn were lower than those for items missing the terminal effect. The causal status effect was also obtained in goodness-of-exemplar judgments (Experiment 2) and in free-sorting tasks (Experiment 3), but it was weaker in similarity judgments than in categorization judgments (Experiment 4). Experiment 5 shows that the size of the causal status effect is moderated by plausibility of causal relations, and Experiment 6 shows that effect features can be useful in retrieving information about unknown causes. We discuss the scope of the causal status effect and its implications for categorization research.     

Acquiring principles of semantic organization

One hundred and forty third and seventh grade children (ages 9 and 13 years) learned familiar animal terms organized and presented either hierarchically, in lists, or randomly. Following multitrial free recall of list items, subjects performed four sorting tasks with the same item set to test for transfer of the organizational principles employed in the original learning. A no-training group at each level also sorted. There was a training effect at both grade levels on the sorting tasks. Groups receiving structured presentations had essentially learned a new lexical organization for the items. As expected, older children applied the learned structures more spontaneously and more accurately than younger children in the same conditions. The importance of a transfer task in assessing changes in subjective organization is stressed.     

Actual and Perceived Group Performance as a Function of Group Composition: The Moderating Role of the Type A and B Behavior Patterns1

This study examined the moderating influence of the Type A and B behavior patterns on group performance and group functioning. Type As and Bs were assigned to different roles in groups given the task of deciding what items to transfer from a sinking ship to a life raft. Results indicated that groups with Type A leaders in conflict with a Type A group member arrived at relatively poor decisions. Type A leaders, however, also were perceived by their groups to be more competent than were Type B leaders. These results suggested that the Type A behavior pattern can have the paradoxical effects of hindering group problem-solving and of leading others to view Type As as more competent than Type Bs because of their active dynamic style.     

Object identification as a function of discriminability and learning presentations: the effect of stimulus similarity and canonical frame alignment on aircraft identification

Aircraft that were relatively similar (homogeneous) and relatively dissimilar (heterogeneous) in appearance were studied at orientations either consistent (canonical) or inconsistent (noncanonical) with the environmental frame of reference. At test, participants' identification performance was measured with stimuli rotated to novel orientations within the picture plane. During learning and testing, identification of heterogeneous aircraft was better than that of homogeneous aircraft. At test, only identification of homogeneous aircraft revealed a strong linear degradation of performance as angular disparity between the novel test orientations and the original learning orientations increased. During learning and testing, identification was better for aircraft studied at canonical orientations than for those studied at noncanonical orientations. The results are discussed in terms of object identification, aircraft recognition training, categorization, mental representations, and visual mental rotation.     

Categorization and cognitive deficits in compulsive hoarding

According to the cognitive-behavioural model of compulsive hoarding, information-processing deficits in the areas of attention, memory, decision-making, and categorization contribute to hoarding behaviour. The purpose of the current study was to examine whether individuals with compulsive hoarding exhibited impairment on executive functioning and categorization tasks. Three groups of participants were recruited (N = 60): individuals with compulsive hoarding syndrome, individuals with an Axis I mood or anxiety disorder, and non-clinical control participants. All participants completed self-report measures of cognitive difficulties, neuropsychological tests of executive functioning and decision-making, and four categorization tasks. Results suggested that hoarding participants reported more cognitive failures and more problems with attention and decision-making than non-clinical control participants. In addition, hoarding participants performed worse than both control groups on the Stockings of Cambridge (SOC), a neuropsychological test of planning ability, and were slower and more anxious during a categorization task. These findings suggest that specific deficits in executive functioning may be associated with the difficulties hoarding patients have organizing their possessions.     

The relational versus collective “We” and intergroup allocation: The role of nested group categorization

Intergroup research has focused primarily, if not solely, on how an intergroup comparative context primes social categorization. The current research examines how individual differences, in terms of distinct forms of social self (the relational versus collective self), differentially drive social categorization and zero-sum resource allocation across groups nested within a superordinate group. Results show that the relational self exhibited more ingroup-biased allocations than the collective self; superordinate categorization mediated this relationship. Moreover, the relational self showed more ingroup-biased allocations under the condition of intergroup competition than cooperation; whereas the collective self showed equally unbiased allocations under the conditions of intergroup competition and cooperation. Our research suggests that competition worsens nested group relations for the relational self, but not for the collective self.     

Does practice in category learning increase rule use or exemplar use—or both?

Categorization research has demonstrated the use of both rules and remembered exemplars in classification, although there is disagreement over whether learners shift from one to the other or use both strategies simultaneously. Theoretical arguments can motivate predictions for both rule use and exemplar use increasing with more practice. We describe a single large experiment (n = 190) that manipulated the number of training items (category size), the number of presentations of each training item, and the similarity between the training and the transfer stimuli in order to discover when rules and exemplars are most likely to be used. Results showed that rules and exemplars both influenced classification and that exemplars were used more often with smaller categories, with more training on items, and when test items were similar to training items. There was no consistent evidence of a shift from rule-based to exemplar-based categorization with more learning. Importantly, we found a number of conditions in which rules and exemplars were both used, even within individual participants. We discuss our results in terms of hybrid models of classification.     

Training attention improves decision making in individuals with elevated self-reported depressive symptoms

Depression is often characterized by attentional biases toward negative items and away from positive items, which likely affects reward and punishment processing. Recent work has reported that training attention away from negative stimuli reduced this bias and reduced depressive symptoms. However, the effect of attention training on subsequent learning has yet to be explored. In the present study, participants were required to learn to maximize reward during decision making. Undergraduates with elevated self-reported depressive symptoms received attention training toward positive stimuli prior to performing the decision-making task (n = 20; active training). The active-training group was compared to two other groups: undergraduates with elevated self-reported depressive symptoms who received placebo training (n = 22; placebo training) and a control group with low levels of depressive symptoms (n = 33; nondepressive control). The placebo-training depressive group performed worse and switched between options more than did the nondepressive controls on the reward maximization task. However, depressives that received active training performed as well as the nondepressive controls. Computational modeling indicated that the placebo-trained group learned more from negative than from positive prediction errors, leading to more frequent switching. The nondepressive control and active-training depressive groups showed similar learning from positive and negative prediction errors, leading to less-frequent switching and better performance. Our results indicate that individuals with elevated depressive symptoms are impaired at reward maximization, but that the deficit can be improved with attention training toward positive stimuli.     

Fostering understanding of multimedia messages through pre-training: evidence for a two-stage theory of mental model construction

Students received a narrated animation explaining the workings of a car's braking system (Experiments 1 and 2) or a bicycle tire pump (Experiment 3) and then took retention and transfer tests. Some students received pre-training concerning each of the components in the system before receiving the narrated animation (pre-training group), whereas others received no pre-training (no pre-training group) or--only in Experiment 3--training after the narrated animation (post-training group). The pre-training described or depicted the possible states of each part. Students in the pre-training group performed better than did students in other groups on tests of transfer (in all 3 experiments) and retention (in Experiments 1 and 2). Results are consistent with a 2-stage theory of mental model construction.     

The double‐edged sword of diversity: Toward a dual pathway model

Williams and O'Reilly (1998) published a seminal review of diversity research that has become a classic resource for researchers and practitioners alike. In the current review, we update the theoretical record by discussing traditional views of, as well as recent developments to, the 3 prominent frameworks used to understand diversity: social categorization, similarity‐attraction, and information and decision‐making. Furthermore, we propose a dual pathway model of diversity's effects that integrates all 3 frameworks. In our model, both positive and detrimental effects of diversity stem from processes of social categorization. Whereas these processes disrupt group functioning when intergroup bias is activated, when bias is not activated, we propose that social categorization and reduced attraction to dissimilar others will allow individuals in diverse rather than homogeneous groups to focus more on the task, anticipate differences in task‐relevant opinions and perspectives, and engage in more effortful information processing. Finding the balance is key.     

Effects of part-set cuing on experienced and novice chess players' reconstruction of a typical chess midgame position

A typical midgame chess position was presented to participants for 30 sec. Participants then reconstructed the presented position on a second board from memory. Following a brief distraction phase, participants were asked to reconstruct the position a second time with 0, 6, or 12 of the original pieces present. It was hypothesized that cue presentation during second reconstruction would be more disruptive to experienced players' recall than to novices'. Recall was measured in terms of correct pieces placed, new items generated (reminiscence), and previously recalled items omitted (forgetting). Analysis indicated that cues neither facilitated nor inhibited recall: experienced players performed better than novice players across recall indices, with the exception of reminiscence at which both groups performed similarly.