Effect of intermittent reinforcement on acquisition and retention in delayed matching-to-sample in pigeons

Experiments 1 and 2 involved independent groups that received primary reinforcement after a correct match with a probability of 1.0, .50 or .25. Correct matches that did not produce primary reinforcement produced a conditioned reinforcer. Both experiments revealed little evidence that acquisition or retention was adversely affected by use of intermittent reinforcement. Experiment 3 involved a group that received 100% reinforcement and two others that received 25% reinforcement, one of which received conditioned reinforcement and the other did not. Following acquisition and retention testing, birds in group 100% and group 25% with conditioned reinforcement were exposed to 25% reinforcement and no conditioned reinforcement. Results revealed that conditioned reinforcement was important in promoting acquisition but was irrelevant in maintaining performance. It was concluded that intermittent reinforcement, especially when combined with conditioned reinforcement during acquisition, supports levels of acquisition and retention comparable to that of continuous reinforcement. Theoretically, the findings are consistent with an extension of Blough's instance-based theory of discrimination performance and, practically, they suggest that use of intermittent reinforcement could result in increased efficiency and economy in labs using delayed matching.     

Adjectives really do modify nouns: the incremental and restricted nature of early adjective acquisition

By 24 months, most children spontaneously and correctly use adjectives. Yet prior laboratory research that has studied lexical acquisition in young children reports that children up to 3-years-old map novel adjectives to object properties only in very limited situations (Child Development 59 (1988) 411; Child Development 64 (1993) 1651; Child Development 71 (2000) 649; Developmental Psychology 36 (2000) 571; Child Development 69 (1998) 1313). In Experiments 1 and 2 we introduced 36-month-olds (Experiment 1) and 24-month-olds (Experiment 2) to novel adjectives while providing rich referential and syntactic information to indicate what the novel words mean. Specifically, we used a given novel adjective to describe multiple familiar objects which shared a salient property; in addition we used the adjectives in full noun phrases, not in conjunction with pronouns. Under these conditions, both groups mapped novel adjectives onto object properties. In Experiment 3 we asked whether the rich referential information was responsible for the successful outcome of the previous two experiments; we introduced novel adjectives to 2- and 3-year-olds as in Experiments 1 and 2, but the adjectives modified nouns of vague (very general) reference ("one", or "thing"). Under these conditions the children failed. We suggest that young word learners require access to the taxonomy of the object type so that the relevant property can be identified. The taxonomically specific nouns of Experiments 1 and 2 accomplish this, whereas the more general, semantically bleached nominals in Experiment 3 do not. Taken together with related findings in the literature, these findings favor an account of lexical acquisition in which layers of information become available incrementally, as a consequence of solving prior parts of the learning problem.     

Preschoolers’ understanding of multiple orientations to reality: The adjectives task

Preschoolers’ understanding that an object can be accurately described using two different non-synonymous words was investigated using a task in which children (N = 36) had to judge which of two animals had provided correct adjectival labels for a series of pictures. For some pictures, only one animal provided a correct adjective, for some both animals were correct, and for some neither was correct. For all types of judgement, 4-year-olds outperformed 3-year-olds. Children in both age groups performed worst on trials where both animals were correct. Children's performance on the adjectives task related to concurrent understanding of the appearance–reality distinction, but not to false-belief task performance. Implications for children's mentalizing development are discussed.     

Basic level and superordinate level categorization by autistic, mentally retarded, and normal children

Three experiments designed to test autistic children's nonverbal and verbal categorization abilities are reported in this paper. In the first two experiments, 14 autistic children were compared to 14 retarded and 14 normal children matched on verbal mental age. Their ability to categorize pictures from basic level categories and from biological and artifactual superordinate level categories was assessed using a matching-to-sample procedure. The three groups of subjects were similar in their performance. Basic level categorization was easier than more abstract categorization, and for all three groups, prototypicality played a role in categorizing superordinate level concepts; that is, children in all three groups made more errors categorizing peripheral examples. In the third experiment, a subgroup of 7 autistic children showed evidence that their lexicons were well organized and that they appreciated the meaning relationships among words at the superordinate level. These findings suggest that autistic children do not suffer a specific cognitive deficit in the ability to categorize and form abstract concepts, as has been previously suggested in the literature.     

EFFECTS OF DIRECT,INTERMITTENT, AND VICARIOUS REINFORCEMENT PROCEDURES ON THE DEVELOPMENT AND MAINTENANCE OF INSTRUCTION-FOLLOWING BEHAVIORS IN A GROUP OF YOUNG CHILDREN1

A group of young children (mean age: 2.5 yr) were instructed to follow different requests by a teacher in a day-care setting. Experiment I verified that mean group instruction following was low (10%) despite the opportunity for “observational learning”, i.e., the group of 12 children could watch a nonreinforced adult comply with the teacher's request. In Experiment II, when positive consequences were provided contingent on the adult model's behavior, mean group instruction following was relatively unaffected (14%). When direct reinforcement was given to four peer models, each for several sessions, the individual performances of three of the four peer models was elevated (from 50% to 80%); however, the mean performance of the remaining nonreinforced children (N = 7) was only moderately affected (21%). When reinforcement contingencies were again changed, so that each group member was provided direct, but intermittent reinforcement, mean group performance increased substantially to levels of over 70%. Once instruction following was high, presentation of reinforcement only to one peer model sufficed to maintain performance whereas earlier, this same vicarious reinforcement procedure had failed to establish group compliance. The maintenance of instruction-following behavior when reinforcement was applied solely to one child was interpreted mainly in terms of a high resistance to extinction following a history of intermittent reinforcement rather than a “vicarious”- or “self”-reinforcement mechanism. Finally, removal and re-introduction of group intermittent reinforcement, respectively, lowered performance (to levels of 40%) and elevated (to levels of 65%) the group's performance.     

A cross-linguistic study of early lexical development

Cross-linguistic studies have shown that children can vary markedly in rate, style, and sequence of grammatical development, within and across natural languages. It is less clear whether there are robust cross-linguistic differences in early lexical development, with particular reference to the onset and rate of growth in major lexical categories (e.g., nouns, verbs, adjectives and grammatical function words). In this study, we present parental report data on the first stages of expressive and receptive lexical development for 659 English infants and 195 Italian infants between 8 and 16 months of age. Although there are powerful structural differences between English and Italian that could affect the order in which nouns and verbs are acquired, no differences were observed between these languages in the emergence and growth of lexical categories. In both languages, children begin with words that are difficult to classify in adult part-of-speech categories (i.e., “routines”). This is followed by a period of sustained growth in the proportion of vocabulary contributed by common nouns. Verbs, adjectives, and grammatical function words are extremely rare until children have vocabularies of at least 100 words. The same sequences are observed in production and comprehension, although verbs are reported earlier for receptive vocabulary. Our results are compared with other reports in the literature, with special reference to recent claims regarding the early emergence of verbs in Korean.     

Typicality effects in picture‐word interference paradigm: An evaluation of the response exclusion hypothesis

The response exclusion hypothesis suggests that the polarity of semantic effects in the picture‐word interference paradigm is determined by the response‐relevant criteria. Semantic interference effects would be observed when semantically related distractor words satisfy the response‐relevant criteria; otherwise, semantic facilitation effects should be found. The purpose of this study was to further evaluate the response exclusion hypothesis by exploring the typicality effects in pictures naming. In two experiments, pictures of objects were named either in the context of verb distractor words with different typicality of passive functions or in the context of adjective distractor words with different typicality of characteristics. Facilitation effects were observed in context of typical verbs and adjectives, while interference effects were observed in the context of atypical verbs and adjectives. Given that neither typical nor atypical distractor words satisfy the response‐relevant criteria to produce noun, these findings are problematic for the response exclusion hypothesis. Role of syntagmatic relationships in lexical retrieval was invoked to explain present findings.