Exemplar effects in categorization and multiple-cue judgment.

Categorization and multiple-cue judgment are similar tasks, but the influential models in the two areas are different in terms of the computations, processes, and neural substrates that they imply. In categorization, exemplar memory is often emphasized, whereas multiple-cue judgment generally is interpreted in terms of integration of Cues that have been abstracted in training. In 3 experiments the authors investigated whether these conclusions derive from genuine differences in the processes or are accidental to the different research methods. The results revealed large individual differences and a shift from exemplar memory to cue abstraction when the criterion is changed from a binary to a continuous variable, especially for a probabilistic criterion. People appear to switch between qualitatively distinct processes in the 2 tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response-time tests of logical-rule models of categorization.

A recent resurgence in logical-rule theories of categorization has motivated the development of a class of models that predict not only choice probabilities but also categorization response times (RTs; Fifi?, Little, & Nosofsky, 2010). The new models combine mental-architecture and random-walk approaches within an integrated framework and predict detailed RT-distribution data at the level of individual participants and individual stimuli. To date, however, tests of the models have been limited to validation tests in which participants were provided with explicit instructions to adopt particular processing strategies for implementing the rules. In the present research, we test conditions in which categories are learned via induction over training exemplars and in which participants are free to adopt whatever classification strategy they choose. In addition, we explore how variations in stimulus formats, involving either spatially separated or overlapping dimensions, influence processing modes in rule-based classification tasks. In conditions involving spatially separated dimensions, strong evidence is obtained for application of logical-rule strategies operating in a serial-self-terminating processing mode. In conditions involving spatially overlapping dimensions, preliminary evidence is obtained that a mixture of serial and parallel processing underlies the application of rule-based classification strategies. The logical-rule models fare considerably better than major extant alternative models in accounting for the categorization RTs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construct validation and internal consistency of the geometric categorization task (GEOCAT) for measuring primary and secondary processes.

The GEOCAT is a short nonverbal test for measuring two types of cognition that tally with Freud's distinction between primary and secondary unconscious processes: attributional and relational similarity judgment. Attributional similarity judgment is a mode of cognitive categorization in which stimuli are classified based on perceptual resemblances between attributes and features, just like in primary processing. Relational similarity judgment is a mode of cognitive categorization that builds on higher order relationships between stimuli, just like in secondary processing. The GEOCAT can be used in diverse research contexts, and test administration takes 2 minutes. The present study investigates the construct validity and internal consistency of this instrument in a sample of Belgian university students. A confirmatory factor analysis for binary items indicates that a dimension reflecting relational or attributional categorization processes lies behind the GEOCAT items, that this model has a good fit to the data, and that all items are equally good indicators of these processes. We also compared the GEOCAT to an alternative measure that builds on a continuous scale for similarity judgment. Correlations between corresponding subscales were moderate and three GEOCAT items proved to be problematic. Internal consistency proved to be good. Suggestions for future research on similarity judgment and primary and secondary processes are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Adaptive categorization in unsupervised learning.

In 3 experiments, the authors provide evidence for a distinct category-invention process in unsupervised (discovery) learning and set forth a method for observing and investigating that process. In the 1st 2 experiments, the sequencing of unlabeled training instances strongly affected participants' ability to discover patterns (categories) across those instances. In the 3rd experiment, providing diagnostic labels helped participants discover categories and improved learning even for instance sequences that were unlearnable in the earlier experiments. These results are incompatible with models that assume that people learn by incrementally tracking correlations between individual features; instead, they suggest that learners in this study used expectation failure as a trigger to invent distinct categories to represent patterns in the stimuli. The results are explained in terms of J. R. Anderson's (1990, 1991) rational model of categorization, and extensions of this analysis for real-world learning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cue Patterns and Alcohol Expectancies: How Slight Differences in Stimuli Can Measurably Change Cognition.

Expectancy theory states that environmental cues provide the information necessary for organisms to predict what is upcoming in the world. Because this information is vast, mechanisms of simplification such as identification of cue patterns are thought to be necessary. This study tested the influence of 2 different cue patterns on alcohol-related cognition. By simply changing the 1st word (milk vs. beer) on a study list comprising alcohol expectancy and grocery words, content differences in recalled words were demonstrated. Additionally, differences were a product of experience with alcohol. Findings were consistent with what would be predicted by cognitive concepts such as hybrid cuing and point to the need to take context and individual experience into account when studying memory processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory capacity and categorization: Individual differences and modeling.

Working memory is crucial for many higher-level cognitive functions, ranging from mental arithmetic to reasoning and problem solving. Likewise, the ability to learn and categorize novel concepts forms an indispensable part of human cognition. However, very little is known about the relationship between working memory and categorization, and modeling in category learning has thus far been largely uninformed by knowledge about people's memory processes. This article reports a large study (N = 113) that related people's working memory capacity (WMC) to their category-learning performance using the 6 problem types of Shepard, Hovland, and Jenkins (1961). Structural equation modeling revealed a strong relationship between WMC and category learning, with a single latent variable accommodating performance on all 6 problems. A model of categorization (the Attention Learning COVEring map, ALCOVE; Kruschke, 1992) was fit to the individual data and a single latent variable was sufficient to capture the variation among associative learning parameters across all problems. The data and modeling suggest that working memory mediates category learning across a broad range of tasks. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Emotion concepts and emotional states in social judgment and categorization.

An objection to conclusions of research investigating effects of emotions on cognitive processes is that the effects are due to the activation of semantic concepts rather than to emotional feelings. A sentence unscrambling task was developed to prime concepts of happiness, sadness, or neutral ideas. Pilot studies demonstrated that unscrambling emotional sentences did not affect emotional state but did prime semantically related words. Experiment 1 showed that the induction of emotional state but not the sentence unscrambling task produced emotion-congruent judgments. Results of Experiment 2 showed that individuals in emotional states categorized according to emotional equivalence more often than participants in a neutral state. Sentence unscrambling had no effect on emotional response categorization. The influences of emotions and emotion knowledge in cognition and emotion are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The effect of embodied emotive states on cognitive categorization.

Research has uncovered that positive affect broadens cognitive categorization. The motivational dimensional model, however, posits that positive affect is not a unitary construct with only one cognitive consequence. Instead, this model puts forth that there are different positive affects varying in approach motivational intensity. According to this model, only positive affects lower in motivational intensity should broaden cognitive processes, whereas positive affects higher in motivational intensity should narrow cognitive processes. Consistent with these predictions, high approach positive affect has been shown to narrow attention, whereas low approach positive affect has been shown to broaden it (Gable & Harmon-Jones, 2008). High approach positive affect, therefore, might narrow categorization. Two experiments investigated this possibility by having participants respond to cognitive categorization tasks in 3 body postures designed to elicit different levels of approach motivation: reclining backward, which should evoke low approach motivation; sitting upright, which should evoke moderate approach motivation; and leaning forward, which should evoke high approach motivation. Participants smiled while in each posture in order to experience positive affect. Experiment 1 provided initial support for the idea that high approach positive affect narrows categorization and low approach positive affect broadens categorization. Experiment 2 replicated these findings with improved smiling instructions. These results extend previous work by showing that the motivational model's predictions hold for basic attentional processes as well as higher level cognitive processes such as categorization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning and attention in multidimensional identification and categorization: Separating low-level perceptual processes and high-level decisional processes.

Four observers completed identification and categorization tasks. Learning and attention processes were examined by applying general recognition theory (F. G. Ashby & J. T. Townsend, 1986), which separates perceptual, decisional, and attentional processes. Learning led to decision regions that became more nearly optimal. Learning had little effect on perceptual processes in identification and decisional integration categorization tasks but affected perceptual processes in decisional selective attention categorization tasks, leading to perceptual selective attention. These findings suggest that (a) identification and categorization invoke decision strategies that are localized in the striatum (F. G. Ashby, E. M. Waldron, W. W. Lee, & A. Berkman, 2001) and (b) perceptual and decisional attention systems exist and are mediated by distinct brain structures (M. I. Posner & S. E. Petersen, 1990). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causal status and coherence in causal-based categorization.

Research has documented two effects of interfeature causal knowledge on classification. A causal status effect occurs when features that are causes are more important to category membership than their effects. A coherence effect occurs when combinations of features that are consistent with causal laws provide additional evidence of category membership. In this study, we found that stronger causal relations led to a weaker causal status effect and a stronger coherence effect (Experiment 1), that weaker alternative causes led to stronger causal status and coherence effects (Experiment 2), and that “essentialized” categories led to a stronger causal status effect (Experiment 3), albeit only for probabilistic causal links (Experiment 4). In addition, the causal status effect was mediated by features' subjective category validity, the probability they occur in category members. These findings were consistent with a generative model of categorization but inconsistent with an alternative model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distinguishing prototype-based and exemplar-based processes in dot-pattern category learning.

The authors contrast exemplar-based and prototype-based processes in dot-pattern categorization. In Experiments 1A and 1B, participants provided similarity ratings of dot-distortion pairs that were distortions of the same originating prototype. The results show that comparisons to training exemplars surrounding the prototype create flat typicality gradients within a category and small prototype-enhancement effects, whereas comparisons to a prototype center create steep typicality gradients within a category and large prototype-enhancement effects. Thus, prototype and exemplar theories make different predictions regarding common versions of the dot-distortion task. Experiment 2 tested these different predictions by having participants learn dot-pattern categories. The steep typicality gradients, the large prototype effects, and the superior fit of prototype models suggest that participants refer to-be-categorized items to a representation near the category's center (the prototype), and not to the training exemplars that surround the prototype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cue reactivity in cannabis-dependent adolescents.

The authors measured event-related potentials with a craving manipulation to investigate the neural correlates of drug cue reactivity in 13 adolescents who are cannabis dependent (CD; ages 14–17). The P300 responses to marijuana (MJ) pictures (MJ-P300) and control pictures (C-P300) were assessed after handling neutral objects and again after handling MJ paraphernalia (MJP). Self-reported drug craving and heart rates also were measured. MJ-P300 were larger than C-P300 (p p = .002 and p = .003, respectively), with no association between the magnitude of craving and MJ-P300. Heart rates were not affected by handling MJP. The results showed that adolescents who are CD have an attentional bias to MJ stimuli that increases after handling marijuana paraphernalia. Generally, the results are consistent with what has been reported for adult heavy chronic cannabis smokers, although there were some differences that require further investigation. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effect of Cue Exposure, Urge to Smoke, and Nicotine Deprivation on Cognitive Performance in Smokers.

The primary aim of this investigation was to test the hypothesis that the urge to smoke interferes directly with cognitive performance. Fifty-four smokers were randomly assigned to 1 of 3 groups: (a) ad lib, (b) deprived, or (c) nicotine patch. Participants rated their urge to smoke on continuous visual analogue scales. Cognitive performance was determined by measuring reaction times (RTs) on a Sternberg task. The deprived group reported a higher urge and had longer RTs than the ad lib group when exposed to smoking-related cues. However, the nicotine patch group reported a higher urge in the absence of longer RTs. The results indicated that nicotine deprivation affects cognitive performance and that the urge to smoke only partially mediated RTs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modulation of the Impairment of Hippocampectomized Rats on the Radial-Arm Maze Cue Task by Visual Characteristics and Subicular Damage.

Rats with N-methyl-D-aspartate lesions of the hippocampus that partially damaged the subiculum and controls were trained on 2 versions of the radial-arm maze cue task, with either proximal or distal visual stimuli. In Experiment 1, the relative positions of the stimuli varied across trials. Lesioned rats were impaired when trained on the distal version, as opposed to transiently slowed down when trained on the proximal version. In Experiment 2, the relative positions of the stimuli were fixed throughout training. Lesioned rats were impaired when trained on the distal or the proximal version. Further analyses showed that combined damage to the hippocampus and the subiculum was required to impair performance in the proximal, but not the distal, version. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feature and rule selection in categorization tasks.

The process by which stimuli are assigned to categories has been traditionally conceptualized as bottom-up. Accordingly, stimulus features are supposed to be the fundamental units of analysis, and categorization to be accomplished on the basis of feature category correlations (cue validities). Alternatively, top-down processes are invoked, in which case one begins with a given categorization rule and then assigns stimuli to categories on that basis. Bottom-up and top-down views share a fundamental weakness, namely, they are unable to specify how features or rules, respectively, are acquired. This difficulty can be overcome if it is assumed that the process starts with neither features nor rules, but with stimuli. Then, as a result of experience with stimuli belonging to different categories, the cognitive system discovers and uses locally constructed features that maximally discriminate between the categories at hand. According to this view, the relationship between a target and a contrast category is the main factor affecting what subjects learn about each. Two experiments were conducted to explore this hypothesis. Both experiments support the notion that the relationship between the target and contrast category significantly determines which critical features are extracted as being defining of either category. In particular, it determines the level of generality of these features. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus type, level of categorization, and spatial-frequencies utilization: Implications for perceptual categorization hierarchies.

The type of visual information needed for categorizing faces and nonface objects was investigated by manipulating spatial frequency scales available in the image during a category verification task addressing basic and subordinate levels. Spatial filtering had opposite effects on faces and airplanes that were modulated by categorization level. The absence of low frequencies impaired the categorization of faces similarly at both levels, whereas the absence of high frequencies was inconsequential throughout. In contrast, basic-level categorization of airplanes was equally impaired by the absence of either low or high frequencies, whereas at the subordinate level, the absence of high frequencies had more deleterious effects. These data suggest that categorization of faces either at the basic level or by race is based primarily on their global shape but also on the configuration of details. By contrast, basic-level categorization of objects is based on their global shape, whereas category-specific diagnostic details determine the information needed for their subordinate categorization. The authors conclude that the entry point in visual recognition is flexible and determined conjointly by the stimulus category and the level of categorization, which reflects the observer’s recognition goal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Specific exemplar retention and prototype abstraction in young and old adults.

Examined the effects of age differences in retention of information about specific concept members on 40 older adults' (mean age 72.3 yrs) and 40 younger adults' (mean age 20.6 yrs) ability to abstract central tendency information. The mean Wechsler Adult Intelligence Scale—Revised (WAIS—R) Vocabulary scaled score for the young adults was significantly lower than that of the older adults. Ss were presented with a series of visual patterns that were organized around a prototype and were then presented with these same patterns plus a set of new patterns varying in prototype similarity in a recognition test. It was found that young Ss retained more information about specific acquisition set exemplars, which resulted in slightly different recognition responses for new patterns. However, the recognition behavior of both young and older Ss appeared to be governed by the same rules. It is suggested that the organization of conceptual information does not change with age but that the poorer retention of specific item information in older adults may result in a less complete representation. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related deficits in component processes of working memory.

Working memory deficits in normal aging have been well documented, and studies suggest that high memory load plus the presence of distraction negatively impacts successful memory performance to a greater degree in older individuals. However, characterization of the component processes that are impaired by these task manipulations is not clear. In this behavioral study, younger and older subjects were tested with a delayed-recognition and recall task in which the encoding and delay period were both manipulated. During the encoding period, the subjects were presented with either a single letter or multiple letters at their predetermined forward letter span, and the delay period was either uninterrupted or interrupted with a visual distraction. There was an age-related impairment of working memory recognition accuracy only in the combination of high memory load and distraction. These results suggest that when working memory maintenance systems are taxed, faulty recognition processes may underlie cognitive aging deficits in healthy older individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decoupling object detection and categorization.

We investigated whether there exists a behavioral dependency between object detection and categorization. Previous work (Grill-Spector & Kanwisher, 2005) suggests that object detection and basic-level categorization may be the very same perceptual mechanism: As objects are parsed from the background they are categorized at the basic level. In the current study, we decouple object detection from categorization by manipulating the between-category contrast of the categorization decision. With a superordinate-level contrast with people as one of the target categories (e.g., cars vs. people), which replicates Grill-Spector and Kanwisher, we found that success at object detection depended on success at basic-level categorization and vice versa. But with a basic-level contrast (e.g., cars vs. boats) or superordinate-level contrast without people as a target category (e.g., dog vs. boat), success at object detection did not depend on success at basic-level categorization. Successful object detection could occur without successful basic-level categorization. Object detection and basic-level categorization do not seem to occur within the same early stage of visual processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intramaze and Extramaze Cue Processing in Adult APPSWE Tg2576 Transgenic Mice.

The present study examined spatial and nonspatial learning in adult Tg2576 mice. Transgenic mice were impaired in acquisition of a T-maze forced-choice alternation task. However, mutant mice were as sensitive as control mice to the introduction of retention intervals and proactive interference, and this suggested that short-term memory processes were intact in Tg2576 mice. Probe trials revealed that the Tg2576 mice did not use an allocentric strategy to navigate to the goal arm. However, mutant mice acquired an intramaze brightness discrimination, a simple room discrimination, and a contextual biconditional left-right discrimination in a T maze. Results suggest that Tg2576 mice are able to process both intramaze and extramaze stimuli but are impaired in forming an allocentric representation of their environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)