Analysis of discriminative control by social behavioral stimuli

Visual discriminative control of the behavior of one rat by the behavior of another was studied in a two-compartment chamber. Each rat's compartment had a food cup and two response keys arranged vertically next to the clear partition that separated the two rats. Illumination of the leader's key lights signaled a “search” period when a response by the leader on the unsignaled and randomly selected correct key for that trial illuminated the follower's keys. Then, a response by the follower on the corresponding key was reinforced, or a response on the incorrect key terminated the trial without reinforcement. Accuracy of following the leader increased to 85% within 15 sessions. Blocking the view of the leader reduced accuracy but not to chance levels. Apparent control by visual behavioral stimuli was also affected by auditory stimuli and a correction procedure. When white noise eliminated auditory cues, social learning was not acquired as fast nor as completely. A reductionistic position holds that behavioral stimuli are the same as nonsocial stimuli; however, that does not mean that they do not require any separate treatment. Behavioral stimuli are usually more variable than nonsocial stimuli, and further study is required to disentangle behavioral and nonsocial contributions to the stimulus control of social interactions.     

Imitation and novelty in product development

A human stigmergy model of product development through a series of incremental novelties and imitations is obtained by observing the isomorphism between solution trees generated by groups of humans participating in online games like Foldit, self-organizing topics in online learning systems, product evolution through a combination of innovation and imitation in the cell phone industry, and social networks formed over the past 40 years in creation of the Boston biotech commons. The model incorporates two very simple rules: (1) preferential attachment, and (2) the combination of existing product designs into a single design. A computer model used to simulate the model produces product evolution networks isomorphic to observed solution trees and product evolution trees. Additionally, industries with a high degree of novelty produce a product evolution network with scale-free and betweenness centrality structure.     

Infant recall memory and communication predicts later cognitive development

This longitudinal study investigates the relation between recall memory and communication in infancy and later cognitive development. Twenty-six typically developing Swedish children were tested during infancy for deferred imitation (memory), joint attention (JA), and requesting (nonverbal communication); they also were tested during childhood for language and cognitive competence. Results showed that infants with low performance on both deferred imitation at 9 months and joint attention at 14 months obtained a significantly lower score on a test of cognitive abilities at 4 years of age. This long-term prediction from preverbal infancy to childhood cognition is of interest both to developmental theory and to practice.     

Generalization of deferred imitation during the first year of life

Infants first generalize across contexts and cues at 3 months of age in operant tasks but not until 12 months of age in imitation tasks. Three experiments using an imitation task examined whether infants younger than 12 months of age might generalize imitation if conditions were more like those in operant studies. Infants sat on a distinctive mat in a room in their home (the context) while an adult modeled actions on a hand puppet (the cue). When they were tested 24 h later, 6-month-olds generalized imitation when either the mat or the room (but not both) differed, whereas 9-month-olds generalized when both the mat and the room differed. In addition, 9-month-olds who imitated immediately also generalized to a novel test cue, whereas 6-month-olds did not. These results parallel results from operant studies and reveal that the similarity between the conditions of encoding and retrieval-not the type of task-determines whether infants generalize. The findings offer further evidence that memory development during infancy is a continuous function.     

Behavioral treatment of children with phonological disorder: the efficacy of vocal imitation and sufficient-response-exemplar training

This study examined whether sufficient-response-exemplar training of vocal imitation would result in improved articulation in children with phonological disorder, and whether improved articulation established in the context of vocal imitation would transfer to other verbal classes such as object naming and conversational speech. Participant 1 was 6 years old and attended first grade in a regular public school. Participant 2 was 5 years 4 months old and attended a public kindergarten. Both participants had normal hearing and no additional handicaps. A multiple baseline design across behaviors (target sounds or blends) was employed to examine whether the vocal imitation training resulted in improved articulation. Results showed that both participants improved articulation once training was implemented, and that the improved articulation transferred from vocal imitation to more natural speech such as object naming and conversational speech. Improvement established during training was maintained posttraining and at a 6-month follow-up.     

Effects of serial versus concurrent task sequencing an acquisition, maintenance, and generalization

Effects of serial and concurrent task presentation on skill acquisition, generalization, and maintenance were compared. Two severely retarded females participated. During serial training, items of one response class, tracing, were trained to mastery before those of a second task, vocal imitation. In the concurrent method, training on two different tasks, tracing and vocal imitation, alternated within sessions for fixed periods of time. There were no major differences between the serial and concurrent methods of instruction in the number of steps attained per behavior or in the number of trials required to reach criterion levels of performance. It was found however, that concurrent training resulted in more generalization. Retention results were not consistently related to training method.     

THE EFFECT OF EXPERIMENTER FACIAL ORIENTATION DURING IMITATION MAINTENANCE1

The training and maintenance of imitative responding has become an important therapeutic process with language-handicapped children, as indicated by Garcia and DeHaven (American Journal of Mental Deficiency, 1974, 79 , 169–178). Typically a training “package” is used, that might entail the use of operant shaping, fading, reinforcement, and punishment techniques designed to increase correct imitation and decrease incorrect responding. Only recently have studies begun to concentrate on the components of these training “packages”. Steinman (Journal of Applied Behavior Analysis, 1970, 3 , 159–167) highlighted the roles played by less conspicuous but functionally important components of these packages. The present study attempted to provide a systematic extension of this work within an applied context. Using subjects who were responding at high levels during an imitation-maintenance procedure, experimenter facial orientation (experimenter's eyes and head oriented towards the subject's face and head), was systematically manipulated for experimentally determined “types” of imitative behavior. Differential responding within these parameters provided an evaluation of facial orientation as a functional component within this training package. Three retarded children participated in the study. Two types of topographically different imitative responses were defined for experimental purposes (“standing” and “sitting”). Each subject progressed through four conditions of the study, which called for the reinforcement of all imitative responses. But during preselected conditions, experimenter facial orientation was removed from the therapeutic package for one of the two topographical types of imitation. Results indicated that imitation of the two topographical types of models was dependent on the presence of experimenter facial orientation within the experimental procedure.     

Transient effects of acquisition history on generalization in a matching-to-sample task

This study examined the role of learning history on the acquisition of a matching-to-sample task. Twelve preschool children learned four stimulus classes through instructions, shaping, or imitation. After reaching criterion, the subjects were exposed to changed discrimination contingencies to determine how each learning history affected the acquisition of responses appropriate to the new contingencies. All subjects reached criterion on the new relations, although the subjects with a shaping history adapted slightly more quickly than those subjects with a history of instructions or imitation. Given sufficient exposure to changed contingencies, rule-driven insensitivity to contingencies was overcome by experience with consequences. This result may be specific to younger subjects, but it suggests that instructions can be used in education without creating insensitivity to contingencies.     

Exact person fit indexes for the rasch model for arbitrary alternatives

A new algorithm for obtaining exact person fit indexes for the Rasch model is introduced which realizes most powerful tests for a very general family of alternative hypotheses, including tests concerning DIF as well as model-deviating item correlations. The method is also used as a goodness-of-fit test for whole data sets where the item parameters are assumed to be known. For tests with 30 items at most, exact values are obtained, for longer tests a Monte Carlo-algorithm is proposed. Simulated examples and an empirical investigation demonstrate test power and applicability to item elimination.The author wishes to thank Elisabeth Ponocny-Seliger and the reviewers for many helpful comments. All exact goodness-of-fit tests proposed in this article are implemented in the menu-driven program T-Rasch 1.0 by Ponocny and Ponocny-Seliger (1999) which can be obtained from ProGAMMA (WWW: http://www.gamma.rug.nl) and also performs nonparametric tests.     

The ontogeny of cumulative culture: Individual toddlers vary in faithful imitation and goal emulation

The success of human culture depends on early emerging mechanisms of social learning, which include the ability to acquire opaque cultural knowledge through faithful imitation, as well as the ability to advance culture through flexible discovery of new means to goal attainment. This study explores whether this mixture of faithful imitation and goal emulation is based in part on individual differences which emerge early in ontogeny. Experimental measurements and parental reports were collected for a group of 2‐year‐old children (N = 48, age = 23–32 months) on their imitative behavior as well as other aspects of cognitive and social development. Results revealed individual differences in children's imitative behavior across trials and tasks which were best characterized by a model that included two behavioral routines; one corresponding to faithful imitation, and one to goal emulation. Moreover, individual differences in faithful imitation and goal emulation were correlated with individual differences in theory of mind, prosocial behavior, and temperament. These findings were discussed in terms of their implications for understanding the mechanisms of social learning, ontogeny of cumulative culture, and the benefit of analyzing individual differences for developmental experiments.