The role of different social reinforcement contingencies in inducing echoic tacts through motor imitation responding in children with severe language delays.

Abstract

One of the major challenges that special educators are presented with when working with children with developmental disabilities is teaching vocal communication skills to nonvocal children. About 50% of children with autism do not display functional speech and they require intensive behavioral interventions to acquire an effective communication system (Whetherby & Prizant, 2000; Williams & Greer, 1993). Skinner in his book Verbal Behavior (1957) identified several verbal functions distinguished by the occasions in which they occur and the consequences they produce. The three verbal operants directly or indirectly related to this study are the echoic, the mand and the tact. Echoic verbal behavior is defined as the verbal response under the control of verbal stimuli that generates a sound pattern similar to that of the stimulus (Skinner, 1957). For example, after an adult says cat, a child responds, cat. The critical characteristic of echoic verbal behavior is the point-to-point correspondence between the verbal stimulus and the response, as well as the temporal relation between the stimulus and the response (later reproduction of overheard speech is not echoic behavior). Another critical characteristic is that the reinforcer for the tact is a generalized reinforcer that is typically social in nature (Greer & Ross, 2008). The mand is a verbal operant that specifies its reinforcer, under the functional control of relevant conditions of deprivation or aversive stimulation. For example, the response I want is evoked under conditions of deprivation from water and specifies to the listener that water will be an effective reinforcer. The tact is controlled by a nonverbal discriminative stimulus (an object, event or property of an object or event) and is reinforced by a non-specific generalized conditioned reinforcement, such as attention, praise or repetition of the response (Stafford, Sundberg & Braam, 1988). For example, a child says, airplane in the presence of an actual A listener consequates this response saying, that's right, it is an airplane. Skinner's (1957) theory of verbal behavior gave rise to empirical research that investigated the verbal operants he identified and led to the development of applied instructional tactics and curricula. Whetherby and Prizant (2000) described a shift from highly structured discrete trial training curricula (Lovaas, 1977) to contemporary applied behavioral analysis approaches, which incorporate the environmental variables that control verbal behavior on a moment-to-moment basis (i.e., deprivation, satiation, aversive stimulation conditions, generalized social reinforcement, stimulus control, history of the organism, natural context in which communication occurs) (Greer & Ross, 2008; Hall & Sundberg, 1987; Hart & Risely, 1974; Partington & Sundberg, 1998). However, one need not wait for naturally occurring conditions to evoke verbal operants, since recent work has shown that the motivating conditions can be designed, thus ensuring many more opportunities to acquire the verbal operants (Fiorile & Greer, 2007; Greer & Ross, 2008; Pistoljevic & Greer, 2006; Schauffler & Greer, 2006) Williams and Greer (1993) introduced the echoic to mand and the echoic to tact teaching operations for verbal behavior, where the student has to emit a certain number of echoic responses before being presented with opportunities for independent responses, mands or tacts. During the echoic to mand procedure, the therapist creates momentary deprivation states from preferred items, through a choice component (two preferred items are introduced at the same time). During the echoic to tact procedure, correct tacting of non-preferred items results in a generalized reinforcer (e.g., token or praise) and/or the opportunity to mand a preferred item. Establishing operations or motivative variables, such as deprivation, satiation or aversive stimulation play a critical role in the acquisition of mands (Michael, 1982; Michael, 1983; Michael, 2000; Skinner, 1957). …