Classes and collections: Internal organization and resulting holistic properties

This work presents an analysis of a type of concept, the collection, not readily characterized by class inclusion models. Collections, the referents of collective nouns (e.g., pile, family, bunch), are argued to differ from classes in (a) how membership can be determined, (b) part-whole relationships, (c) internal structure, and (d) the nature of the higher order units they form. From this analysis, it is hypothesized that the psychological integrity of collections is greater than that of classes. Collections and objects, in contrast to classes, both require specified relationships among the parts and both result in a coherent psychological unit. It was suggested that objects form a relatively more stable unit than collections. Corresponding to this analysis the degree of psychological integrity is hypothesized to lead to different degrees of difficulty in making part-whole comparisons for objects, collections, and classes in modified Piagetian class-inclusion paradigms. The hypothesized difference in performance was found for collections and classes and an alternative linguistic explanation for the greater success with collections was eliminated. However, children performed equally well on tasks involving collections and objects, raising the possibility that when elements are organized into collections, they form psychological units which are as coherent as objects.     

Partial reinforcement effects in instrumental escape conditioning

In Experiment I acquisition and extinction of instrumental escape conditioning with rats (N = 64) were studied as a function of reinforcement magnitude under conditions of partial and continuous reinforcement. In Experiment II the effects of partial and continuous reinforcement were studied in rats (N = 96) during acquisition followed by small, medium, and large reductions in reinforcement magnitude. A water-tank escape apparatus was used with temperature as the relevant variable. It was found that (1) with large reinforcement magnitude a continuously reinforced group was superior in acquisition to one that was partially reinforced; there were no differences with small reinforcement; (2) disruptive effects of a nonreinforced trial (a) appear early in learning, (b) are quite strong after each nonreinforced trial, and (c) persist through several succeeding reinforced trials; (3) major competing behaviors persist throughout acquisition for small reinforcement magnitude regardless of schedule, decline with large reinforcement (more so with continuous than with partial), and return to a high level in extinction for all conditions; (4) the partial reinforcement extinction effect occurs after large reinforcement but not after small, and it appears only with large reductions in reinforcement magnitude which approach extinction conditions. Only the first part of the last finding appears to be consistent with the appetitive conditioning literature.     

Extending the classical view of representation

Representation has always been a central part of models in cognitive science, but this idea has come under attack. Researchers advocating the alternative approaches of perceptual symbol systems, situated action, embodied cognition, and dynamical systems have argued against central assumptions of the classical representational approach to mind. We review the core assumptions of the representational view and these four suggested alternatives. We argue that representation should remain a core part of cognitive science, but that the insights from these alternative approaches must be incorporated into models of cognitive processing.     

Appearance questions can be misleading: a discourse-based account of the appearance-reality problem

Preschoolers' success on the appearance-reality task is a milestone in theory-of-mind development. On the standard task children see a deceptive object, such as a sponge that looks like a rock, and are asked, "What is this really?" and "What does this look like?" Children below 412 years of age fail saying that the object not only is a sponge but also looks like a sponge. We propose that young children's difficulty stems from ambiguity in the meaning of "looks like." This locution can refer to outward appearance ("Peter looks like Paul") but in fact often refers to likely reality ("That looks like Jim"). We propose that "looks like" is taken to refer to likely reality unless the reality is already part of the common ground of the conversation. Because this joint knowledge is unclear to young children on the appearance-reality task, they mistakenly think the appearance question is about likely reality. Study 1 analyzed everyday conversations from the CHILDES database and documented that 2 and 3-year-olds are familiar with these two different uses of the locution. To disambiguate the meaning of "looks like," Study 2 clarified that reality was shared knowledge as part of the appearance question, e.g., "What does the sponge look like?" Study 3 used a non-linguistic measure to emphasize the shared knowledge of the reality in the appearance question. Study 4 asked children on their own to articulate the contrast between appearance and reality. At 91%, 85%, and 81% correct responses, children were at near ceiling levels in each of our manipulations while they failed the standard versions of the tasks. Moreover, we show how this discourse-based explanation accounts for findings in the literature. Thus children master the appearance-reality distinction by the age of 3 but the standard task masks this understanding because of the discourse structure involved in talking about appearances.     

The absence of a shape bias in children's word learning

There is debate about whether preschool-age children interpret words as referring to kinds or to classes defined by shape similarity. The authors argue that the shape bias reported in previous studies is a task-induced artifact rather than a genuine word-learning strategy. In particular, children were forced to extend an object's novel label to one of several stand-alone, simple-shaped items, including a same-shape option from a different category and a different-shape option from the same superordinate category. Across 6 experiments, the authors found that the shape bias was eliminated (a) when the objects were more complex, (b) when they were presented in context, or (c) when children were no longer forced to choose. Moreover, children preferred the different-shape category alternatives when these were part of the same basic-level category as the target. The present experiments suggest that children seek out objects of the same kind when presented with a novel label, even if they are sometimes unable to identify the relevant kinds on their own.     

Word learning in dogs?

In a recent paper, Kaminski, Call and Fischer report pioneering research on word-learning in a dog. In this commentary we suggest ways of distinguishing referential word use from mere association. We question whether the dog is reasoning by exclusion and, if so, compare three explanations - learned heuristics, default assumptions, and pragmatic reasoning - as they apply to children and might apply to dogs. Kaminski et al.'s work clearly raises important questions about the origins and basis of word learning and social cognition.     

The research misconception

Recently, several researchers and philosophers argued that clinical research trials are not therapy. Their position is based on foundational research ethics documents, such as the Belmont Report, on conceptual analysis, and on the general way clinical trials are conducted. After examining and rejecting these arguments, we claim that good research is consistent with good therapy; that often trials are good therapy; and that a blanket attack on clinical trials as non-therapeutic creates a research misconception. This misconception is potentially harmful because it could weaken trial recruitment, could adversely affect funding for trials, and could overturn needed moral safeguards on therapeutic trials. Our more careful and accurate analysis of the nature of clinical trials can avoid such problems.     

Use of the mutual exclusivity assumption by young word learners

A critical question about early word learning is whether word learning constraints such as mutual exclusivity exist and foster early language acquisition. It is well established that children will map a novel label to a novel rather than a familiar object. Evidence for the role of mutual exclusivity in such indirect word learning has been questioned because: (1) it comes mostly from 2 and 3-year-olds and (2) the findings might be accounted for, not by children avoiding second labels, but by the novel object which creates a lexical gap children are motivated to fill. Three studies addressed these concerns by having only a familiar object visible. Fifteen to seventeen and 18-20-month-olds were selected to straddle the vocabulary spurt. In Study 1, babies saw a familiar object and an opaque bucket as a location to search. Study 2 handed babies the familiar object to play with. Study 3 eliminated an obvious location to search. On the whole, babies at both ages resisted second labels for objects and, with some qualifications, tended to search for a better referent for the novel label. Thus mutual exclusivity is in place before the onset of the naming explosion. The findings demonstrate that lexical constraints enable babies to learn words even under non-optimal conditions--when speakers are not clear and referents are not visible. The results are discussed in relation to an alternative social-pragmatic account.