Perceptual and semantic sources of category-specific effects: event-related potentials during picture and word categorization

In two experiments the effect of object category on event-related potentials (ERPs) was assessed while subjects performed superordinate categorizations with pictures and words referring to objects from natural (e.g., animal) and artifactual (e.g., tool) categories. First, a category probe was shown that was presented as name in Experiment 1 and as picture in Experiment 2. Thereafter, the target stimulus was displayed. In both experiments, analyses of the ERPs to the targets revealed effects of category at about 160 msec after target onset in the pictorial modality, which can be attributed to category-specific differences in perceptual processing. Later, between about 300-500 msec, natural and artifactual categories elicited similar ERP effects across target and category modalities. These findings suggest that perceptual as well as semantic sources contribute to category-specific effects. They support the view that semantic knowledge associated with different categories is represented in multiple subsystems that are similarly accessed by pictures and words.     

Distinguishing the effects of action relations and scene context on object perception

Objects are rarely viewed in isolation, and so how they are perceived is influenced by the context in which they are viewed and their interaction with other objects (e.g., whether objects are colocated for action). We investigated the combined effects of action relations and scene context on an object decision task. Experiment 1 investigated whether the benefit for positioning objects so that they interact is enhanced when objects are viewed within contextually congruent scenes. The results indicated that scene context influenced perception of nonaction-related objects (e.g., monitor and keyboard), but had no effect on responses to action-related objects (e.g., bottle and glass) that were processed more rapidly. In Experiment 2, we reduced the saliency of the object stimuli and found that, under these circumstances, scene context influenced responses to action-related objects. We discuss the data in terms of relatively late effects of scene processing on object perception.     

Measuring the influence of similarity on category-specific effects

There is evidence for both advantages and disadvantages in normal recognition of living over nonliving things. This paradox has been attributed to high levels of perceptual similarity within living categories having a different effect on performance in different contexts. However, since living things are intrinsically more similar to each other, previous studies could not determine whether the various category effects were due to perceptual similarity, or to other characteristics of living things. We used novel animal and vehicle stimuli that were matched for similarity to measure the influence of perceptual similarity in different contexts. We found that displaying highly similar objects in blocked sets reduced their perceived similarity, eliminating the detrimental effect on naming performance. Experiment 1 demonstrated a disadvantage for highly similar objects in name learning and name verification using mixed groups of similar and dissimilar animals and vehicles. Experiment 2 demonstrated no disadvantage for the same highly similar objects when they were blocked, e.g., similar animals presented alone. Thus, perceptual similarity, rather than other characteristics particular to living things, is affected by context, and could create apparent category effects under certain testing conditions.     

Processing of perceptual information is more robust than processing of conceptual information in preschool-age children: evidence from costs of switching

Is processing of conceptual information as robust as processing of perceptual information early in development? Existing empirical evidence is insufficient to answer this question. To examine this issue, 3- to 5-year-old children were presented with a flexible categorization task, in which target items (e.g., an open red umbrella) shared category membership with one test item (e.g., a folded umbrella) and perceptual characteristics with another test item (e.g., a red mushroom). Participants were instructed to either categorize stimuli by the same dimension (i.e., perceptual similarity or category membership) in both phases of the task, or switch from categorizing by one dimension to categorizing by the other dimension. Results pointed to a strong asymmetry in switch costs: conceptual switch costs were higher than perceptual switch costs. These results suggest that processing of perceptual information remains more robust than processing of conceptual information at least until 5 years of age.     

The effects of relational structure on analogical learning

Relational structure is important for various cognitive tasks, such as analogical transfer, but its role in learning of new relational concepts is poorly understood. This article reports two experiments testing people’s ability to learn new relational categories as a function of their relational structure. In Experiment 1, each stimulus consisted of 4 objects varying on 2 dimensions. Each category was defined by two binary relations between pairs of objects. The manner in which the relations were linked (i.e., by operating on shared objects) varied between subjects, producing 3 logically different conditions. In Experiment 2, each stimulus consisted of 4 objects varying on 3 dimensions. Categories were defined by three binary relations, leading to six logically different conditions. Various learning models were compared to the behavioral data, based on the theory of schema refinement. The results highlight several shortcomings of schema refinement as a model of relational learning: (1) it can make unreasonable demands on working memory, (2) it does not allow schemas to grow in complexity, and (3) it incorrectly predicts learning is insensitive to relational structure. We propose schema elaboration as an additional mechanism that provides a more complete account, and we relate this mechanism to previous proposals regarding interactions between analogy and representation construction. The current findings may advance understanding of the cognitive mechanisms involved in learning and representing relational concepts.     

Specialization and semantic organization: Evidence for multiple semantics linked to sensory modalities

The present article reviews the case for multiple systems in semantic memory and empirically evaluates a multiple semantics proposal based on sensory modalities. In the experiments, a conceptual switching cost paradigm was used (Pecher, Zeelenberg, & Barsalou, 2003), in which participants verified properties for concepts and verification time was compared for target trials (e.g., a dog can bark) that were preceded by context trials of either the same or a different modality (e.g., a bee can buzz or a horse can have spots). Experiment 1 involved a modality switch while controlling for the concept's category and demonstrated that when modalities were switched, a processing cost was incurred that could not be attributed to the latter dimension. Experiment 2 further supported this conclusion by showing that, in a reverse situation, the cost incurred when category was switched was at least smaller. The results are discussed by considering possible alternative amodal explanations and other data that have shown the influence of sensory information in conceptual processing.     

Perceptual processing of nontargets in an attention task

The capability of nontargets to qualitatively influence the semantic processing of coincident targets was investigated in three experiments. Subjects were aurally presented a series of word pairs and attempted to detect homonymic instances of a predesignated category (e.g., animals). The nontarget with which a target (e.g., ANT) was paired was appropriate (e.g., CRAWLING), inappropriate (e.g., UNCLE), or neutral (e.g., STRAW). Experiments 1 and 2 established that detection of targets can be facilitated by appropriate nontargets and inhibited by inappropriate ones. Thus, nontargets can influence the way in which targets are semantically represented. Experiment 3 showed that this effect is eliminated when subjects are precued as to the ear of entry of targets. Thus, precuing appears to curtail the perceptual processing of nontargets. The data run counter to theories that claim that focused attention does not entail the perceptual suppression of nontargets.     

Object manipulability affects children’s and adults’ conceptual processing

Research on kinds of concepts indicates that children use perceptual and functional information differently to form natural and artifact concepts. Beyond object domain, object manipulability appears to be a decisive factor in adult conceptual processing. Thus, the effect of object manipulability on conceptual processing was tested in 5- and 7-year-olds and adults using a picture matching task. Reaction times for identifying conceptual relations on the basis of perceptual similarity (e.g., jacket-coat) and contextual/functional information (e.g., jacket-hanger) were analyzed according to object manipulability and domain. Both children and adults were faster to identify contextual/functional relations for manipulable than for nonmanipulable objects. Conversely, they were faster to identify perceptual similarity relations for nonmanipulable than for manipulable objects, particularly for natural concepts. Results reveal an early distinction between concepts of manipulable and nonmanipulable objects. Implications for further research on concept formation and for embodied views of concepts are discussed.     

The world in black and white: Ostracism enhances the categorical perception of social information

In two experiments, ostracized individuals showed more pronounced categorical perception of inclusion- and exclusion-related stimuli. Specifically, ostracism enhanced the ability to distinguish between-category differences (e.g., between happy and angry faces) relative to within-category differences (e.g., between two happy expressions). Participants were socially included or excluded via Cyberball (a virtual ball-tossing task). In Experiment 1, ostracized participants showed greater perceptual acuity in distinguishing between subtly happy and angry expressions combined with a reduced ability to discriminate expressions within each expression category. Experiment 2 found analogous categorical perception effects for targets varying on the dimension of race. Importantly, this effect was specific to social information; categorical perception of non-social objects was not qualified by social exclusion. These results suggest that ostracism exacerbates categorical perception, attuning perceivers to the differences between various inclusion- and exclusion-related categories relative to within category acuity, making the world appear more ‘black-and-white’ than it might otherwise.     

Psychophysics of the McGurk and other audiovisual speech integration effects

When the auditory and visual components of spoken audiovisual nonsense syllables are mismatched, perceivers produce four different types of perceptual responses, auditory correct, visual correct, fusion (the so-called McGurk effect), and combination (i.e., two consonants are reported). Here, quantitative measures were developed to account for the distribution of the four types of perceptual responses to 384 different stimuli from four talkers. The measures included mutual information, correlations, and acoustic measures, all representing audiovisual stimulus relationships. In Experiment 1, open-set perceptual responses were obtained for acoustic /bɑ/ or /lɑ/ dubbed to video /bɑ, dɑ, gɑ, vɑ, zɑ, lɑ, wɑ, eɑ/. The talker, the video syllable, and the acoustic syllable significantly influenced the type of response. In Experiment 2, the best predictors of response category proportions were a subset of the physical stimulus measures, with the variance accounted for in the perceptual response category proportions between 17% and 52%. That audiovisual stimulus relationships can account for perceptual response distributions supports the possibility that internal representations are based on modality-specific stimulus relationships.     

Associations to unfamiliar words: Learning the meanings of new words

Five experiments were designed to examine whether subjects attend to different aspects of meaning for familiar and unfamiliar words. In Experiments 1–3, subjects gave free associations to high- and low-familiarity words from the same taxonomic category (e.g.,seltzer:sarsparilla; Experiment 1), from the same noun synonym set (e.g.,baby:neonate; Experiment 2), and from the same verb synonym set (e.g.,abscond:escape; Experiment 3). In Experiments 4 and 5, subjects first read a context sentence containing the stimulus word and then gave associations; stimuli were novel words or either high- or low-familiarity nouns. Low-familiarity and novel words elicited more nonsemantically based responses (e.g.,engram:graham) than did high-familiarity words. Of the responses semantically related to the stimulus, low-familiarity and novel words elicited a higher proportion of definitional responses [category (e.g.,sarsparilla:soda), synonym (e.g.,neonate:newborn), and coordinate (e.g.,armoire:dresser)], whereas high-familiarity stimuli elicited a higher proportion of event-based responses [thematic (e.g.,seltzer:glass) and noun:verb (e.g.,baby:cry)]. Unfamiliar words appear to elicit a shift of attentional resources from relations useful in understanding the message to relations useful in understanding the meaning of the unfamiliar word.     

Modulation of taxonomic (versus thematic) similarity judgments and product choices by inducing local and global processing

Perceived similarity is influenced by both taxonomic and thematic relations. Assessing taxonomic relations requires comparing individual features of objects whereas assessing thematic relations requires exploring how objects functionally interact. These processes appear to relate to different thinking styles: abstract thinking and a global focus may be required to explore functional interactions whereas attention to detail and a local focus may be required to compare specific features. In four experiments we explored this idea by assessing whether a preference for taxonomic or thematic relations could be created by inducing a local or global perceptual processing style. Experiments 1–3 primed processing style via a perceptual task and used a choice task to examine preference for taxonomic (versus thematic) relations. Experiment 4 induced processing style and examined the effect on similarity ratings for pairs of taxonomic and thematically related items. In all cases processing style influenced preference for taxonomic/thematic relations.     

Mechanisms underlying priming on perceptual tests.

Four experiments examined perceptual, lexical, and conceptual processing effects in priming on word fragment completion (WFC) and perceptual identification (PID). In Experiment 1, visual words produced more priming than auditory or generated words, and pictures produced the least priming, suggesting that the effects of different encoding processes can be distinguished. In Experiments 2 and 3, Ss studied anagrams (e.g., tripocs), but only Ss instructed to think of the original words by mentally interchanging the vowels exhibited significant priming. Thus, lexical access is more important than surface similarity in priming. In Experiment 4, Ss studied compounds that either preserved the target's meaning (e.g., scotch bottle) or altered its meaning (e.g., scotch tape). Encoded meaning affected priming on WFC but not on PID, suggesting that conceptual processing plays a larger role in WFC. Overall the results suggest that priming must be understood in terms of multiple processes.     

An Information Space for Partial Length Perception in Dynamic Touch

Two experiments evaluated change in the perception of an environmental property (object length) in each of 3 perceptual modalities (vision, audition, and haptics) when perceivers were provided with the opportunity to experience the same environmental property by means of an additional perceptual modality (e.g., haptics followed by vision, vision followed by audition, or audition followed by haptics). Experiment 1 found that (a) posttest improvements in perceptual consistency occurred in all 3 perceptual modalities, regardless of whether practice included experience in an additional perceptual modality and (b) posttest improvements in perceptual accuracy occurred in haptics and audition but only when practice included experience in an additional perceptual modality. Experiment 2 found that learning curves in each perceptual modality could be accommodated by a single function in which auditory perceptual learning occurred over short time scales, haptic perceptual learning occurred over middle time scales, and visual perceptual learning occurred over long time scales. Analysis of trial-to-trial variability revealed patterns of long-term correlations in all perceptual modalities regardless of whether practice included experience in an additional perceptual modality.     

Relational properties and memory-based category construction.

Although many experiments have investigated factors that constrain perceptual category construction, there have been no investigations of factors that constrain memory-based (MB) category construction. Six experiments examined the extent to which perceptual and MB sorting were influenced by correlated dimensions, family resemblance principles, and conceptual knowledge. Sensitivity to many types of relational information (e.g., correlated features, causal relations, interactive properties of objects, and family resemblance relations) was observed with perceptual sorting, but these properties were rarely used to organize information in MB sorting conditions. Instead, there was a clear preference to organize categories around single dimensions. Even when perfectly correlated features were causally related, Ss in memory conditions did not use correlations to construct categories. The strengths and limitations of MB analyses and categorizations are discussed.     

The interaction between social saliency and perceptual saliency

The ability to select visual targets in hierarchical stimuli can be affected by both perceptual saliency and social saliency. However, the functional relations between the effects are not understood. Here we examined whether these two factors interact or combine in an additive way. Participants first learnt to associate geometric shapes with three people (e.g., triangle–self, square–stranger). After learning the associations, participants were presented with compound stimuli (e.g., a global triangle formed by a set of local squares) and had to select a target at the global or local level. In Experiment 1 the task was to identify the person associated with the local or global shape. In Experiment 2 the task was simply to identify the shape. We manipulated perceptual saliency by blurring local elements to form perceptually global salient stimuli or by contrasting the colours of neighbouring local elements (red vs. white) to form perceptually local salient stimuli. In Experiment 1 (person discrimination) there was a strong effect of saliency on local targets (there were faster and more accurate responses to high than to low saliency targets) when social and perceptual saliency occurred at same level. However, both perceptual and social saliency effects were eliminated when the effect of saliency at one level competed with that at the other level. In Experiment 2 (shape discrimination), there were only effects of perceptual saliency. The data indicate that social saliency interacts with perceptual saliency when explicit social categorizations are made, consistent with both factors modulating a common process of visual selection.     

Associative and categorical processes in children's memory: The role of automaticity in the development of organization in free recall

Free recall performance was assessed in children in Grades 3, 5, 7, and 9 (Experiment 1) and adults (Experiment 2) on a list of categorically related words constructed so that some items within a category were highly associated with one another and interitem associations were low among other items (e.g., dog, cat, cow, lion, tiger). Associative relations were used frequently in recall by subjects of all ages, with analyses of interitem latencies and correlations between recall and clustering indicating that organization in recall was based only on associative relations for the third and fifth graders but based on both associative and nonassociative categorical relations for older subjects. Examination of the placement of high associates in recall indicated that seventh- and ninth-grade children were more apt to use associative relations to begin category clusters than were younger children or adults. These children were hypothesized to use the relatively automatic activation of associative relations to instigate categorical organization and to represent a stage in development between nonstrategic younger children and strategic adults. The results were discussed in terms of the role that the automatic activation of semantic memory relations may play in the development of strategic memory organization.     

Global precedence in attended and nonattended objects

In four experiments we evaluated whether there is a priority in early perceptual analysis for the global aspect of a nonattended, visual, compound stimulus. In all experiments, two objects were distinguished by being enclosed in either a square or a circle, and each object consisted of a larger letter constructed from smaller letters. Attention was directed to one of the two objects on the basis of either the square/circle distinction (Experiments 1, 2, and 3) or a visual precue (Experiment 4). In agreement with previous findings, for attended objects, the global aspect was identified faster and was more difficult to ignore than the local aspect. However, for nonattended objects, no evidence was found for an overall priority in perceptual processing leading to identification of the global aspect. Rather, the results indicate that there is a priority in perceptual processing for the general category of the global information contained within nonattended objects. Although the results provide some support for the view that global information receives priority during early perceptual analysis, aspects of the results are more consistent with postidentification accounts of global precedence.     

Visual attention and the apprehension of spatial relations: The case of depth

Several studies have shown that targets defined on the basis of the spatial relations between objects yield highly inefficient visual search performance (e.g., Logan, 1994; Palmer, 1994), suggesting that the apprehension of spatial relations may require the selective allocation of attention within the scene. In the present study, we tested the hypothesis that depth relations might be different in this regard and might support efficient visual search. This hypothesis was based, in part, on the fact that many perceptual organization processes that are believed to occur early and in parallel, such as figure-ground segregation and perceptual completion, seem to depend on the assignment of depth relations. Despite this, however, using increasingly salient cues to depth (Experiments 2–4) and including a separate test of the sufficiency of the most salient depth cue used (Experiment 5), no evidence was found to indicate that search for a target defined by depth relations is any different than search for a target defined by other types of spatial relations, with regard to efficiency of search. These findings are discussed within the context of the larger literature on early processing of three-dimensional characteristics of visual scenes.     

The development and robustness of young children’s understanding of aspectuality

We investigated whether 6-year-olds’ understanding of perceptual aspectuality was sufficiently robust to deal with the presence of irrelevant information. A total of 32 children chose whether to look or feel to locate a specific object (identifiable by sight or touch) from four objects that were hidden. In half of the trials, the objects were different on only one modality (e.g., four objects that felt different but were the same color). In the remainder of the trials, the objects also differed (partially) on one irrelevant modality (e.g., four objects that felt different, two red and two blue, where the goal was to locate the soft object). Performance was worse on the latter trials. We discuss children’s difficulty in dealing with irrelevant information.