The benefit of categorization in visual search: Target location without identification

Prior studies have shown that between-category visual search (e.g., looking for a “6” among letters) is easier that within-category search (e.g., looking for a “6” among other digits). Four experiments were performed to determine what particular benefits are conferred in between-category search. The first experiment demonstrates that this category-effect occurs even when the subject has to identify the target, this suggests that the between-category search can “tag” the categorially different item for further processing. Three further experiments provide evidence that this tag is based on the item’s spatial location within the array.     

Turning the tables: language and spatial reasoning

This paper investigates possible influences of the lexical resources of individual languages on the spatial organization and reasoning styles of their users. That there are such powerful and pervasive influences of language on thought is the thesis of the Whorf-Sapir linguistic relativity hypothesis which, after a lengthy period in intellectual limbo, has recently returned to prominence in the anthropological, linguistic, and psycholinguistic literatures. Our point of departure is an influential group of cross-linguistic studies that appear to show that spatial reasoning is strongly affected by the spatial lexicon in everyday use in a community (e.g. Brown, P., & Levinson, S. C. (1993). Linguistic and nonlinguistic coding of spatial arrays: explorations in Mayan cognition (Working Paper No. 24). Nijmegen: Cognitive Anthropology Research Group, Max Planck Institute for Psycholinguistics; Cognitive Linguistics 6 (1995) 33). Specifically, certain groups customarily use an externally referenced spatial-coordinate system to refer to nearby directions and positions ("to the north") whereas English speakers usually employ a viewer-perspective system ("to the left"). Prior findings and interpretations have been to the effect that users of these two types of spatial system solve rotation problems in different ways, reasoning strategies imposed by habitual use of the language-particular lexicons themselves. The present studies reproduce these different problem-solving strategies in speakers of a single language (English) by manipulating landmark cues, suggesting that language itself may not be the key causal factor in choice of spatial perspective. Prior evidence on rotation problem solution from infants (e.g. Acredolo, L.P. (1979). Laboratory versus home: the effect of environment on the 9-month-old infant's choice of spatial reference system. Developmental Psychology, 15 (6), 666-667) and from laboratory animals (e.g. Restle, F. (1975). Discrimination of cues in mazes: a resolution of the place-vs.-response question. Psychological Review, 64, 217-228) suggests a unified interpretation of the findings: creatures approach spatial problems differently depending on the availability and suitability of local landmark cues. The results are discussed in terms of the current debate on the relation of language to thought, with particular emphasis on the question of why different cultural communities favor different perspectives in talking about space.     

Argument structure and the child's contribution to language learning

One of the oldest questions in cognitive science asks whether children are able to learn language (or anything) because they are equipped with a very powerful general-purpose learning mechanism or because they are equipped with a domain-specific constrained language acquisition device. Recent advances in statistical approaches to language learning seem to boost the plausibility of general-purpose learning. However, in this article we propose that in the domain of verb learning, children rely more on their internally generated preconceptions about linguistic structure than on robust cues in the input, suggesting that at least in this aspect of language learning, domain-specific grammatical knowledge guides linguistic development.     

Propose but verify: Fast mapping meets cross-situational word learning

We report three eyetracking experiments that examine the learning procedure used by adults as they pair novel words and visually presented referents over a sequence of referentially ambiguous trials. Successful learning under such conditions has been argued to be the product of a learning procedure in which participants provisionally pair each novel word with several possible referents and use a statistical-associative learning mechanism to gradually converge on a single mapping across learning instances [e.g., Yu, C., & Smith, L. B. (2007). Rapid word learning under uncertainty via cross-situational statistics. Psychological Science, 18(5), 414–420]. We argue here that successful learning in this setting is instead the product of a one-trial procedure in which a single hypothesized word-referent pairing is retained across learning instances, abandoned only if the subsequent instance fails to confirm the pairing – more a ‘fast mapping’ procedure than a gradual statistical one. We provide experimental evidence for this propose-but-verify learning procedure via three experiments in which adult participants attempted to learn the meanings of nonce words cross-situationally under varying degrees of referential uncertainty. The findings, using both explicit (referent selection) and implicit (eye movement) measures, show that even in these artificial learning contexts, which are far simpler than those encountered by a language learner in a natural environment, participants do not retain multiple meaning hypotheses across learning instances. As we discuss, these findings challenge ‘gradualist’ accounts of word learning and are consistent with the known rapid course of vocabulary learning in a first language.     

Human simulations of vocabulary learning

The work reported here experimentally investigates a striking generalization about vocabulary acquisition: Noun learning is superior to verb learning in the earliest moments of child language development. The dominant explanation of this phenomenon in the literature invokes differing conceptual requirements for items in these lexical categories: Verbs are cognitively more complex than nouns and so their acquisition must await certain mental developments in the infant. In the present work, we investigate an alternative hypothesis; namely, that it is the information requirements of verb learning, not the conceptual requirements, that crucially determine the acquisition order. Efficient verb learning requires access to structural features of the exposure language and thus cannot take place until a scaffolding of noun knowledge enables the acquisition of clause-level syntax. More generally, we experimentally investigate the hypothesis that vocabulary acquisition takes place via an incremental constraint-satisfaction procedure that bootstraps itself into successively more sophisticated linguistic representations which, in turn, enable new kinds of vocabulary learning. If the experimental subjects were young children, it would be difficult to distinguish between this information-centered hypothesis and the conceptual change hypothesis. Therefore the experimental "learners" are adults. The items to be "acquired" in the experiments were the 24 most frequent nouns and 24 most frequent verbs from a sample of maternal speech to 18-24-month-old infants. The various experiments ask about the kinds of information that will support identification of these words as they occur in mother-to-child discourse. Both the proportion correctly identified and the type of word that is identifiable changes significantly as a function of information type. We discuss these results as consistent with the incremental construction of a highly lexicalized grammar by cognitively and pragmatically sophisticated human infants, but inconsistent with a procedure in which lexical acquisition is independent of and antecedent to syntax acquisition.     

Why stereotypes don't even make good defaults

Many concepts have stereotypes. This leaves open the question of whether concepts are stereotypes. It has been argued elsewhere that theories that identify concepts with their stereotypes or with stereotypical properties of their instances (e.g., Rosch, E. (1978). Principles of categorization. In E. Rosch & B. B. Lloyd (Ed.), Cognition and Categorization. Hillsdale, NJ: Lawrence Erlbaum Associates; Smith, E. E., Medin, D. L. (1981). Categories and Concepts. Cambridge, MA: Harvard University Press.) fail to provide an adequate account of the compositionality of concepts (Fodor, J., Lepore, E. (1996). The red herring and the pet fish: Why concepts still cannot be prototypes. Cognition, 58, 253-270.; Fodor, J. (1998). Concepts: Where cognitive science went wrong. New York, NY: Oxford University Press.). This paper extends this argument and reports an experiment suggesting that participants do not assume, even as a default strategy, that complex concepts inherit the stereotypes of their constituents. Thus propositions such as "Baby ducks have webbed feet" were judged to be less likely to be true than propositions like "Ducks have webbed feet." Moreover, manipulation of the type and number of noun phrase modifiers revealed a systematic departure from the unmodified noun's stereotype both with the addition of stereotypical modifiers ("Quacking ducks have webbed feet" versus "Ducks have webbed feet") and with the addition of a second modifier ("Baby Peruvian ducks have webbed feet" versus "Baby ducks have webbed feet"). Thus, in the general case the stereotypical properties of a head noun are systematically discounted when that head noun combines with modifiers. This effect represents a general principle of conceptual combination that argues against the inheritance of stereotypical features of concepts as a default strategy. Instead, we advocate a model of conceptual combination where concepts remain inert under combination, supported by a separate machinery that introduces pragmatic and knowledge-dependent inferences.     

The effect of set on categorization in visual search

Two experiments examine whether set for a categorial difference or set for a target category is necessary in order to obtain the category effect in visual search. Eliminating a set for categorial difference does not diminish the size of the effect. When subjects are prevented from developing a useful set for the target category, however, the category effect is eliminated.     

Perceptual completion of surfaces in infancy

Two experiments provide evidence that 4-month-old infants perceive background surfaces as continuous behind occluding objects. Infants were shown a partly hidden background surface either for a brief period of familiarization (Experiment 1) or until they met a criterion of habituation (Experiment 2). The infants were then tested with nonoccluded surfaces that were either continuous or interrupted by a gap where the occluder had been. The infants in each study looked longer at the interrupted than at the continuous surface, relative to infants in baseline controls, which suggests that the partly hidden surface was perceived as continuous. Contrasting findings were obtained in a third experiment, in which infants were habituated to a partly hidden surface that stood in front of a background so that its edges were visible: Infants gave no evidence of perceiving the foreground surface as continuous behind the occluder. These experiments provide evidence that infants perceive a surface as continuous only if it serves as the background of a scene. The results are discussed in relation to figure-ground perception in pictures and surface layouts.