Causes of taxonomic sorting by adults: a test of the thematic-to-taxonomic shift

The tendency among adults to sort items into taxonomic and thematic categories was examined in two experiments. Past demonstrations of adults’ preference for taxonomic categories have usually not used stimuli with a salient thematic organization. The stimuli in Experiment 1 could be divided into three equal-size categories either thematically or taxonomically. Under two sets of instructions, the majority of the college-student subjects sorted thematically. In Experiment 2, a subset of the stimuli was changed so that those within it were strongly taxonomically organized. Subjects then preferred to sort the remaining items taxonomically as well. The two experiments explain why many past sorting studies have yielded a taxonomic preference in adults and provide further evidence against a global change from thematic to taxonomic preference with development.     

Discrimination of five-dimensional stimuli by pigeons: Limitations of feature analysis

Pigeons were trained to discriminate between stimuli constructed using five orthogonal two-valued features. The stimuli consisted of stylized monochrome drawings of seeds. Two different training procedures (conditional and simultaneous discrimination) were used. In the first two experiments, the discrimination required was between polymorphous categories, in which a positive stimulus was defined as one in which three or more of the five features took their positive values. Discrimination in both experiments was imperfect; the pigeons' behaviour only came under the control of a subset of the available features (one to three in Experiment 1, three or four in Experiment 2). In Experiment 3, single features had to be discriminated, while the remaining features varied. It was found that all five features of the “seed” stimuli could be discriminated, but one of them was exceptionally difficult. The results show that pigeons do not reliably use all the features available to them when making category discriminations. This casts doubts on feature analysis as a basis for the excellent performance pigeons show when required to discriminate between categories of natural objects.     

Processing of facial and non‐facial visual stimuli in 2–5‐year‐old children

The present experiments examined the degree to which analytic and holistic modes of processing play a role in the way 2–5‐year‐old children process facial and non‐facial visual stimuli. Children between 2 and 5 years of age were instructed to categorize faces (in Experiment 1) and non‐facial visual stimuli, such as birds and planes (in Experiment 2), into two categories. The categories were so constructed as to allow the children to categorize the facial and non‐facial stimuli either analytically (by focusing on a single attribute) or holistically (in terms of overall similarity). The results demonstrated that the previous conclusions concerning older children's (from 6 years onwards) holistic mode of facial processing could not be generalized to younger children because most of the 2–5‐year olds processed the faces by taking single facial attributes into account. A similar pattern of results emerged for the processing of objects, showing that the majority of the children focused on single attributes. Thus, for both visual domains, holistic processing was the exception rather than the rule. Copyright © 2002 John Wiley & Sons, Ltd.     

Thinking straight while seeing red: the influence of anger on information processing

Because angry people apparently rely on heuristic cues when making judgments, anger has been claimed to trigger superficial, nonanalytic information processing. In three studies, the authors found that induced anger promoted analytic processing. Experiment 1 showed that angry participants were more likely to discriminate between weak and strong arguments than participants in neutral moods. Experiment 2 demonstrated that anger overrode dispositional preferences not to process, causing even those low in need for cognition to process analytically. Experiment 3 reconciled these findings with previous work by showing that angry people used accessible, valid, and relevant heuristics but otherwise processed analytically, as indicated by attitude change and elaboration data. Together, these experiments showed that angry people can have both the capacity and motivation to process and that their selective use of heuristics reflects the cue's perceived validity and not the failure to process analytically.     

The Impact of Stimuli Color in Lexical Decision and Semantic Word Categorization Tasks

In two experiments, we examined the impact of color on cognitive performance by asking participants to categorize stimuli presented in three different colors: red, green, and gray (baseline). Participants were either asked to categorize the meaning of words as related to the concepts of “go” or “stop” (Experiment 1) or to indicate if a neutral verbal stimulus was a word or not (lexical decision task, Experiment 2). Overall, we observed performance facilitation in response to go stimuli presented in green (vs. red or gray) and performance inhibition in response to go stimuli presented in red. The opposite pattern was observed for stop‐related stimuli. Importantly, results also indicated that color might also be used to categorize neutral stimuli. Overall, these findings provide support to the green‐go and red‐stop color associations and test the potential functional autonomy acquired by these colors and the boundary conditions to their effects on stimuli categorization.     

Test of a potential link between analytic and nonanalytic category learning and automatic, effortful processing

The link between automatic and effortful processing and nonanalytic and analytic category learning was evaluated in a sample of 29 college undergraduates using declarative memory, semantic category search, and pseudoword categorization tasks. Automatic and effortful processing measures were hypothesized to be associated with nonanalytic and analytic categorization, respectively. Results suggested that contrary to prediction strong criterion-attribute (analytic) responding on the pseudoword categorization task was associated with strong automatic, implicit memory encoding of frequency-of-occurrence information. Data are discussed in terms of the possibility that criterion-attribute category knowledge, once established, may be expressed with few attentional resources. The data indicate that attention resource requirements, even for the same stimuli and task, vary depending on the category rule system utilized. Also, the automaticity emerging from familiarity with analytic category exemplars is very different from the automaticity arising from extensive practice on a semantic category search task. The data do not support any simple mapping of analytic and nonanalytic forms of category learning onto the automatic and effortful processing dichotomy and challenge simple models of brain asymmetries for such procedures.     

刺激材料的整体性知觉对类别建构的影响

采用标准－匹配的实验程序,操纵刺激材料的空间整合性和知觉的整体性水平,探讨逐个呈现刺激材料时影响被试类别建构策略的根本原因。报告了3个实验,结果证明：逐个呈现并不一定会导致被试倾向于家族相似性归类;刺激材料的空间整合性不一定会影响被试的类别建构策略,空间整合和空间分离都可能出现家族相似性和单维归类倾向;刺激材料的整体性知觉水平对类别建构影响明显：知觉为分离则倾向于家族相似性分类;知觉为整体则倾向于单维分类。被试在实验可能采用分析性策略,然而材料的整体性知觉影响了分析的侧重点,从而对类别建构产生了非常重要的影响     

Compared to what? Effects of categorization on hedonic contrast

Test stimuli are rated less “good” following very good context stimuli than when presented either alone or following neutral context stimuli. This diminution in rating is calledhedonic contrast. In two experiments, the degree of hedonic contrast depended on how subjects were instructed to categorize context and test stimuli. Contrast was substantially attenuated if context and test stimuli were said to belong to different categories. The effect was demonstrated for beverages (Experiment 1) and birds (Experiment 2). Stimuli’s hedonic ratings were far less affected by other stimuli declared to belong to a different category than by stimuli declared to belong to a common category.     

Categorization and normalization of vowels by 3-year-old children

A two-alternative, forced-choice procedure was used in two experiments to test 3-year-old children’s categorization of natural vowel tokens produced by several talkers. An appropriate pointing response (right or left) was visually reinforced with one of two television displays. In Experiment 1, the stimuli were isolated tokens of /a/ and /i/ produced by a male adult, a female adult, a male child, and a female child. In Experiment 2, the stimuli were isolated tokens of /æ/ and /∧/ produced by the same talkers. In both experiments, 3-year-olds spontaneously generalized their pointing responses from the male adult vowel tokens to the corresponding vowels produced by the other talkers. Children reinforced for an arbitrary grouping of the two vowel categories persisted in categorizing on the basis of vowel quality. Results from both experiments demonstrate the presence of perceptual constancy for vowel tokens across talkers. In particular, the results from Experiment 2 provide evidence for normalization of isolated, quasi-steady-state vowel tokens because the formant values for tokens of /∧/ produced by the woman and the two children were closer to the formant frequencies of the male adult’s /æ/ than to the male adult’s /∧/.     

Activating Semantic Knowledge During Spoken Words and Environmental Sounds: Evidence From the Visual World Paradigm

Two visual world experiments investigated the activation of semantically related concepts during the processing of environmental sounds and spoken words. Participants heard environmental sounds such as barking or spoken words such as “puppy” while viewing visual arrays with objects such as a bone (semantically related competitor) and candle (unrelated distractor). In Experiment 1, a puppy (target) was also included in the visual array; in Experiment 2, it was not. During both types of auditory stimuli, competitors were fixated significantly more than distractors, supporting the coactivation of semantically related concepts in both cases; comparisons of the two types of auditory stimuli also revealed significantly larger effects with environmental sounds than spoken words. We discuss implications of these results for theories of semantic knowledge.     

Dual-modality monitoring in a classification task: The effects of bilingualism and ageing

Two experiments are reported in which monolingual and bilingual participants who were younger (Experiment 1) or older (Experiment 2) adults performed in a dual-task classification paradigm. Visually (primary task) and auditorily (secondary task) presented stimuli were classified into two categories. The stimuli belonged to two domains, letters or numbers (LN) and animals or musical instruments (AM), and the two task modalities used stimuli from the same (related) or opposite (unrelated) domains. For both age groups, bilinguals were less disrupted than monolinguals in visual sorting in the LN domain, and relatedness affected performance only in the AM domain. The results indicate different processing demands for the two domains, with the simpler domain (LN) favouring bilinguals and the more semantically complex domain (AM) favouring related judgements for the two task modalities.     

Dual-modality monitoring in a classification task: the effects of bilingualism and ageing

Two experiments are reported in which monolingual and bilingual participants who were younger (Experiment 1) or older (Experiment 2) adults performed in a dual-task classification paradigm. Visually (primary task) and auditorily (secondary task) presented stimuli were classified into two categories. The stimuli belonged to two domains, letters or numbers (LN) and animals or musical instruments (AM), and the two task modalities used stimuli from the same (related) or opposite (unrelated) domains. For both age groups, bilinguals were less disrupted than monolinguals in visual sorting in the LN domain, and relatedness affected performance only in the AM domain. The results indicate different processing demands for the two domains, with the simpler domain (LN) favouring bilinguals and the more semantically complex domain (AM) favouring related judgements for the two task modalities.     

Categorization of natural movements by pigeons: visual concept discrimination and biological motion

In three experiments, pigeons were exposed to a discriminated autoshaping procedure in which categories of moving stimuli, presented on videotape, were differentially associated with reinforcement. All stimuli depicted pigeons making defined responses. In Experiment 1, one category consisted of several different scenes of pecking and the other consisted of scenes of walking, flying, head movements, or standing still. Four of the 4 birds for which pecking scenes were positive stimuli discriminated successfully, whereas only 1 of the 4 for which pecking was the negative category did so. In the pecking-positive group, there were differences between the pecking rates in the presence of the four negative actions, and these differences were consistent across subjects. In Experiment 2, only the categories of walking and pecking were used; some but not all birds learned this discrimination, whichever category was positive, and these birds showed some transfer to new stimuli in which the same movements were represented only by a small number of point lights (Johansson's “biological motion” displays). In Experiment 3, discriminations between pecking and walking movement categories using point-light displays were trained. Four of the 8 birds discriminated successfully, but transfer to fully detailed displays could not be demonstrated. Pseudoconcept control groups, in which scenes from the same categories of motion were used in both the positive and negative stimulus sets, were used in Experiments 1 and 3. None of the 8 pigeons trained under these conditions showed discriminative responding. The results suggest that pigeons can respond differentially to moving stimuli on the basis of movement cues alone.     

Perceptual differentiation as a source of category effects in object processing: Evidence from naming and object decision

The locus of category effects in picture recognition and naming was examined in two experiments with normal subjects. Subjects carried out object decision (deciding whether the stimulus is a “real” object or not) and naming tasks with pictures of clothing, furniture, fruit, and vegetables. These categories are distinguished by containing either relatively many exemplars with similar perceptual structures (fruit and vegetables;structurally similar categories), or relatively few exemplars with similar perceptual structures (clothing and furniture;structurally dissimilar categories). In Experiment 1, responses to the stimuli from the structurally similar categories were slower than responses to stimuli from the structurally dissimilar categories, and this effect was larger in the naming than in the object decision task. Further, prior object decisions to stimuli from structurally similar categories facilitated their subsequent naming. In Experiment 2, we orthogonally manipulated object decision and naming as prime and target tasks, again with stimuli from the four categories. Category effects, with responses slower to objects from structurally similar categories, were again larger in naming than in object decision, and these category effects in naming were reduced by priming with both naming and object decision. We interpret the data to indicate that category effects in object naming can reflect visually based competition which is reduced by the preactivation of stored structural knowledge for objects.     

Letter familiarity does not aid feature extraction

Summary Familiarity effects in visual letter processing were examined by means of a mutilation detection task. The uppercase E was used as the non-mutilated letter. One or two horizontal bars of the E were delected, to produce an upright or inverted F or L. These four mutilations of the E were assigned to the same response. In Experiment 1, brief exposure of the stimuli was followed by a backward mask. Experiment 2 was identical to Experiment 1, except that the display duration of the stimulus was increased and the backward mask was omitted. In Experiment 3, the overall luminance of the stimuli (luminance per point times length of the constituent line segments) was held constant. In Experiment 4, the upright and inverted non-E letter occurred in different blocks to encourage a normal (upright) letter processing strategy in the upright letter blocks. Accuracy (Experiment 1) and mean correct response times (all experiments) were not different for the upright and inverted F or for the upright and inverted L. These findings and converging results from other studies indicate that the higher familiarity of the upright letters did not aid feature extraction.     

Transfer to intermediate forms following concept discrimination by pigeons: chimeras and morphs

Two experiments examined pigeons' generalization to intermediate forms following training of concept discriminations. In Experiment 1, the training stimuli were sets of images of dogs and cats, and the transfer stimuli were head/body chimeras, which humans tend to categorize more readily in terms of the head part rather than the body part. In Experiment 2, the training stimuli were sets of images of heads of dogs and cats, and the intermediate stimuli were computer-generated morphs. In both experiments, pigeons learned the concept discrimination quickly and generalized with some decrement to novel instances of the categories. In both experiments, transfer tests were carried out with intermediate forms generated from both familiar and novel exemplars of the training sets. In Experiment 1, the pigeons' transfer performance, unlike that of human infants exposed to similar stimuli, was best predicted by the body part of the stimulus when the chimeras were formed from familiar exemplars. Spatial frequency analysis of the stimuli showed that the body parts were richer in high spatial frequencies than the head parts, so these data are consistent with the hypothesis that categorization is more dependent on local stimulus features in pigeons than in humans. There was no corresponding trend when the chimeras were formed from novel exemplars. In Experiment 2, when morphs of training stimuli were used, response rates declined smoothly as the proportion of the morph contributed by the positive stimulus fell, although results with morphs of novel stimuli were again less orderly.     

Making Probabilistic Relational Categories Learnable

Theories of relational concept acquisition (e.g., schema induction) based on structured intersection discovery predict that relational concepts with a probabilistic (i.e., family resemblance) structure ought to be extremely difficult to learn. We report four experiments testing this prediction by investigating conditions hypothesized to facilitate the learning of such categories. Experiment 1 showed that changing the task from a category‐learning task to choosing the “winning” object in each stimulus greatly facilitated participants' ability to learn probabilistic relational categories. Experiments 2 and 3 further investigated the mechanisms underlying this “who's winning” effect. Experiment 4 replicated and generalized the “who's winning” effect with more natural stimuli. Together, our findings suggest that people learn relational concepts by a process of intersection discovery akin to schema induction, and that any task that encourages people to discover a higher order relation that remains invariant over members of a category will facilitate the learning of putatively probabilistic relational concepts.     

Category-structure effects in picture comparisons

Subjects indicated for a series of trials whether or not two pictures of common objects were from the same category. Reaction time (RT) was recorded. The pool of stimuli used in the series of trials consisted of two pictures representing each of several categories. Half were S categories, members of which were similar; the other half were D categories, which had dissimilar members (this variable is termed category structure). In Experiments 1 and 3, the similarity manipulation defining category structure was based on the concept of basic level categories (Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976). In Experiment 2, category labels were homonyms, and the two members of S or D categories represented one or two senses of the labels, respectively. The principal finding was an effect of category structure (faster RT on trials using stimuli from S categories rather than D categories). These results are interpreted in terms of a model that postulates the use of semantic codes in the task, even on trials where the two stimuli are physically identical.     

Domains and knowledge effects: strategies in object and social classification

This research examined differences in classification strategies in object and social domains. Wattenmaker (1995) found that additive classification rules were more compatible with the social than the object domain. The present experiments examined the generality of these results by using fundamentally different types of social and object categories. A sorting paradigm was used to evaluate the frequency with which subjects used additive strategies. In Experiment 1, the social domain was represented by social events that possess very different properties than core social concepts such as traits or occupations. Even with these types of social materials, however, many more additive strategies and family resemblance sorts occurred with social than object materials. In Experiment 2, the object domain was represented by abstract object categories that were designed to possess properties of core social concepts such as traits. Again, however, more additive strategies and family resemblance sorts occurred with social than object materials. The results indicate that differences in the compatibility between additive strategies and object and social domains are not limited to subsets of categories in these domains but rather extend to many types of object and social categories.     

Categorical shape and color coding by pigeons

Categorical coding is the tendency to respond similarly to discriminated stimuli. Past research indicates that pigeons can categorize colors according to at least three spectral regions. Two present experiments assessed the categorical coding of shapes and the existence of a higher order color category (all colors). Pigeons were trained on two independent tasks (matching-to-sample, and oddity-from-sample). One task involved red and a plus sign, the other a circle and green. On test trials one of the two comparison stimuli from one task was replaced by one of the stimuli from the other task. Differential performance based on which of the two stimuli from the other task was introduced suggested categorical coding rules. In Experiment 1 evidence for the categorical coding of sample shapes was found. Categorical color coding was also found; however, it was the comparison stimuli rather than the samples that were categorically coded. Experiment 2 replicated the categorical shape sample effect and ruled out the possibility that the particular colors used were responsible for the categorical coding of comparison stimuli. Overall, the results indicate that pigeons can develop categorical rules involving shapes and colors and that the color categories can be hierarchical.