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

Abstract

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.

Keywords: generalized imitation; imitation; infants; manual gestures; multiple exemplars; trained matching.

Fig 1

Range of baseline gestures (B1–B10) that featured in the participants' trained baseline matching relations, and of target gestures (T1–T8) in the target matching relations.

Fig 2

Flowchart of the experimental conditions.

Fig 3

Participants' matching performances, plotted for Haf and Mai. Responses on the eight baseline trials in all phases are shown as open circles. Responses on the eight target behavior trials in initial probe sessions for Haf are shown as either a filled triangle, or filled diamond, for the two target behaviors (T4 and T1, respectively) that were replaced subsequently because performance met the trained matching criterion, or as filled circles in cases where participants' matching responses to probes did not meet this criterion. Following the probe sessions, all responses in the remaining generalized imitation test sessions are shown as filled circles. Gray-shaded columns show the numbers of training sessions for each of the four untrained target behaviors in the staggered skills, staggered matching, mixed matching, and 3-week follow up phases of the procedure.

Fig 4

As in Fig. 3, for participants Iolo and Aled. Iolo's probe responses to T1 are shown as filled triangles.

Fig 5

As in Fig. 3, for participants Elin, Cat, and Alaw. Elin's probe responses to T5, T2, T3, and T4 are shown as filled diamonds, equilateral triangles, rhomboids, and right-angled triangles, respectively.

Fig 6

As in Fig. 3, for participants Eleri and Ceri. Eleri's probe responses to T1, T5, and T7 are shown as filled triangles, diamonds, and rhomboids, respectively. Ceri's probe responses to T4 are shown by filled triangles.

Fig 7

As in Fig. 3, for participants Rhun and Caid. Rhun's probe responses to T2, T1, and T4 are shown as filled triangles, diamonds, and rhomboids, respectively. Caid's probe responses to T4 are shown as filled triangles.