Generalized imitation within three response classes in typically developing infants

A preliminary investigation of fixed and repetitive models during object imitation training

Empirically based guidelines for imitation training for children with Autism Spectrum Disorder (ASD) are limited and there is no existing evidence about what types of imitative models foster faster acquisition of imitation in children with ASD. We compared rates of acquisition for two different methods for presenting the imitative model (i.e., repetitive, fixed) in simple (Experiment 1) and conditional (Experiment 2) discrimination arrangements. The results suggest that some children with ASD may acquire imitation more rapidly when repetitive models, rather than fixed models are used to present the target skill. In Experiment 3, we investigated the features of object imitation models that might influence acquisition. The results of Experiment 3 suggest that the dynamic nature of repetitive models might be responsible for the differential acquisition we observed in the earlier two Experiments. Additionally, the presence of an outcome (e.g., stacked blocks) during training does not enhance acquisition.

Multiple Exemplar Training: Some Strengths and Limitations

In successful multiple exemplar training, a set of exemplars that sample the range of stimulus and response topographies is trained, and the full range of performances results. Examples abound in experimental psychology and include abstraction and concept learning, responding to relations, identity matching, rule following, behavioral variability, responding to wh-questions, describing past events, learning sets, and continuous repertoires. Thus, behavior analysts often allude to a history of multiple exemplar training to account for different generalized performances. It is easy to see how a strategy of multiple exemplar training can work with many types of performances, even performances that involve relations between objects or events. However, there appear to be at least two exceptions, where direct multiple exemplar training does not work well: (1) when there are no physical dimensions at all along which generalized performances can emerge, and (2) when the relation between a stimulus and an effective response is complex. Interpretation of the latter type of cases in terms of mediated generalization is outlined and discussed. An experimental and conceptual research program should produce an account of the general limits of multiple exemplar training, and guidelines for the most effective training for generalized skills.

Effects of serial and concurrent training on acquisition and generalization

Despite a large body of research demonstrating that generalization to novel stimuli can be produced by training sufficient exemplars, the methods by which exemplars can be trained remain unclear. The purpose of the current study was to evaluate 2 methods, serial and concurrent presentation of stimuli, to train sufficient exemplars. Five preschool children with developmental delays were taught to identify letters or letter sounds using serial and concurrent presentation. Generalization to untrained exemplars was evaluated for targets trained using each method. Participants reached the mastery criterion in fewer training sessions, on average, using the concurrent method of presentation than the serial method, and the concurrent method also resulted in greater generalization to untrained exemplars.

The impact of body-part-naming training on the accuracy of imitative performances in 2- to 3-year-old children

A series of three experiments explored the relationship between 3-year-old children's ability to name target body parts and their untrained matching of target hand-to-body touches. Nine participants, 3 per experiment, were presented with repeated generalized imitation tests in a multiple-baseline procedure, interspersed with step-by-step training that enabled them to (i) tact the target locations on their own and the experimenter's bodies or (ii) respond accurately as listeners to the experimenter's tacts of the target locations. Prompts for on-task naming of target body parts were also provided later in the procedure. In Experiment 1, only tact training followed by listener probes were conducted; in Experiment 2, tacting was trained first and listener behavior second, whereas in Experiment 3 listener training preceded tact training. Both tact and listener training resulted in emergence of naming together with significant and large improvements in the children's matching performances; this was true for each child and across most target gestures. The present series of experiments provides evidence that naming--the most basic form of self-instructional behavior--may be one means of establishing untrained matching as measured in generalized imitation tests. This demonstration has a bearing on our interpretation of imitation reported in the behavior analytic, cognitive developmental, and comparative literature.

Do infants show generalized imitation of gestures? II. The effects of skills training and multiple exemplar matching training

The determinants of generalized imitation of manual gestures were investigated in 1- to 2-year-old infants. Eleven infants were first trained eight baseline matching relations; then, four novel gestures that the infants did not match in probe trials were selected as target behaviors. Next, in a generalized imitation test in which matching responses to baseline models were intermittently reinforced, but matching responses to target models were not eligible for reinforcement, the infants matched baseline models but not the majority of their target behaviors. To ensure their failure to match the target behaviors was not due to motor constraints, the infants were trained, in a multiple-baseline procedure, to produce the target responses under stimulus control that did not include an antecedent model of the target behavior. There was no evidence of generalized imitation in subsequent tests. When the infants were next trained to match each target behavior to criterion (tested in extinction) in a multiple-baseline-across-behaviors procedure, only 2 infants continued to match all their targets in subsequent tests; the remaining infants matched only some of them. Seven infants were next given mixed matching training with the target behaviors to criterion (tested in extinction); they subsequently matched these targets without reinforcement when interspersed with trials on which matching responses to baseline models were intermittently reinforced. In repeat tests, administered at 3-week intervals, these 7 children (and 2 that did not take part in mixed matching training) continued to match most of their target behaviors. The results support a trained matching account, but provide no evidence of generalized imitation, in 1- to 2-year-old infants.

Influence of Identity versus Oddity Pretraining on Symmetric Matching to Sample

Identity and oddity matching tasks were designed for different groups of 5-yr.-old children. The presentation of tasks continued until all children had shown evidence of appropriate generalization to new stimuli (i.e., generalized identity matching or generalized oddity from sample). All children then received training on an arbitrary matching-to-sample task. Finally, tests of reflexivity and symmetry in responding were carried out in three consecutive sessions. The children in the Identity group showed reflexivity and symmetry in responses on all three tests; the children in the Oddity group showed oddity in responses on all tests, and a gradual increase in symmetry of responses across tests. These results provide evidence against special versions of multiple-exemplar and reinforcement contingency accounts of stimulus equivalence. Versions of the accounts to explain the findings are discussed.

Teaching children generalized imitation skills: a case report

Generalized imitation plays an important role in the acquisition of new skills, in particular language and communication. In this case report a multiple exemplar training procedure, with an errorless learning phase, was used to teach Ben, a 13-year-old child with severe intellectual disabilities, to imitate behaviours modelled by an adult instructor. After exposure to seven multiple exemplars, Ben learned to imitate novel actions to criterion (i.e. generalized imitation). These skills were maintained at 90 percent at 6 week and 18 week follow-up. In line with earlier research, this article provides some further support for the finding that multiple exemplar training can facilitate the reliable emergence of generalized imitation skills. Topographically similar behaviours during the learning phase can be difficult to discriminate and hence can slow the learning process. Future research could explore how generalized imitation supports the development of basic communication and activity skills.

Mothers' and infants' responses to their partners' spontaneous action and vocal/verbal imitation

Twenty mother-infant dyads (10 boys, 10 girls) were videotaped longitudinally at ages 10, 13, 17, and 21 months during in-home free play and bath sessions. Mothers' and infants' responses to their partners' naturally occurring action and vocal/verbal imitations were described, and relations to infants' imitation rates and vocabularies were examined. Mothers' response rates were consistently high and unrelated to infants' imitation rates. As early as 10 months, infants responded to the great majority of maternal imitations, especially action imitations, often with actions. Infants' return imitations to action matching indicated increasing awareness of being imitated. Infants' responses to mothers' vocal/verbal imitation were associated with their later vocabulary levels. Children who would be more lexically advanced at 17 and/or 21 months provided more social responses at 10 months, more socially responsive actions and return verbal imitations at 13 months, and more non-imitative socially responsive words at 17 and 21 months.

Determinants of imitation of hand-to-body gestures in 2- and 3-year-old children

Twenty children, ten 2-year-olds and ten 3-year-olds, participated in an AB procedure. In the baseline phase, each child was trained the same four matching relations to criterion under intermittent reinforcement. During the subsequent imitation test, the experimenter modeled a total of 20 target gestures (six trials each) interspersed with intermittently reinforced baseline trials. In each session, target gestures were selected in a pre-randomized sequence from: Set 1--ear touches; Set 2--shoulder touches; Set 3--midarm touches; and Set 4--wrist touches; subjects' responses to targets were not reinforced. In each target set, half the gestures featured in nursery matching games and were termed common targets whereas the remainder, which were topographically similar but did not feature in the games, served as uncommon targets. The children produced significantly more matching responses to common target models than to uncommon ones. Common responses were also produced as mismatches to uncommon target models more often than vice versa. Response accuracy did not improve over trials, suggesting that "parity" did not serve as a conditioned reinforcer. All children showed a strong bias for "mirroring"--responding in the same hemispace as the modeler. The 2-year-olds produced more matching errors than the 3-year-olds and most children showed a bias for responding with their right hands. The strong effects of training environment (nursery matching games) are consistent with a Skinnerian account, but not a cognitive goal theory account, of imitation in young children.

Do infants show generalized imitation of gestures?

Two experiments were conducted to investigate generalized imitation of manual gestures in 1- to 2-year-old infants. In Experiment 1, 6 infants were first trained four baseline matching relations (e.g., when instructed "Do this", to raise their arms after they saw the experimenter do so). Next, four novel gestures that the infants did not match in probe trials were selected as target behaviors during generalized imitation Test 1; models of these gestures were presented on unreinforced matching trials interspersed with intermittently reinforced baseline matching trials. None of the infants matched the target behaviors. To ensure that these behaviors were in the infants' motor skills repertoires, the infants were next trained to produce them, at least once, under stimulus control that did not include an antecedent model of the target behavior. In repeat generalized imitation trials (Test 2), the infants again failed to match the target behaviors. Five infants (3 from Experiment 1) participated in Experiment 2, which was identical to Experiment 1 except that, following generalized imitation Test 1, the motor-skills training was implemented to a higher criterion (21 responses per target behavior), and in a multiple-baseline, across-target-behaviors procedure. In the final generalized imitation test, 1 infant matched one, and another infant matched two target behaviors; the remaining 17 target behaviors still were not matched. The results did not provide convincing evidence of generalized imitation, even though baseline matching was well maintained and the target behaviors were in the infants' motor skills repertoires, raising the question of what are the conditions that reliably give rise to generalized imitation.

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.