Acquisition

Description of the Strategy

Environmental events (i.e., antecedents and consequences) shape behaviors in an individual's response repertoire. Within educational contexts, acquisition typically has been defined as the first of four hierarchical phases of learning (i.e., acquisition, fluency, maintenance, and generalization) through which novel behaviors are mastered. The term acquisition has been used to describe the transition from unlearned to learned behavior. Acquisition also has been called the period of “initial learning” during which new skills are gained. From a stimulus control perspective, acquisition is predictable and accurate [Page 1128]responding in the presence of antecedent stimuli that are members of a specific stimulus class and predictable, as well as accurate, responding in the presence of antecedent stimuli that are not members of that specific stimulus class.

These definitions of acquisition are relatively straightforward for anyone who has observed the development of new skills. In the common vernacular, the term acquisition often is used loosely to describe a student's progress from “didn't know how” to “can do it now.” This colloquial description, however, may not be adequate for students who master new skills slowly or with difficulty. Using the term acquisition in this colloquial manner ignores several important issues that may help students who experience learning difficulties gain new skills. Therefore, the problem with any discussion of acquisition is defining the boundaries of when acquisition begins and ends and under what conditions it should be indicated. In short, the essential questions about acquisition are determining exactly how much behavior is “good enough” and exactly when the behavior should and should not be occasioned.

The concept of acquisition is best understood within the framework of steady-state and transition state behaviors. Put simply, steady-state behaviors are responses that are (a) accurately performed and (b) stable in their rate or frequency of occurrence. By contrast, transition state behaviors are responses that are in flux or are changing in frequency, shape, or in terms of other response characteristics (such as duration or latency). The process of learning something new can be thought of as a transition from one state to another state of behavior. In this respect, acquisition is a transition state in which a behavior moves from a zero or near-zero level to some specified criterion level of accuracy and frequency. During acquisition, a behavior essentially is moving toward a steady state. Once reached, the skill is said to have been acquired. Therefore, clarity about what the steady state (i.e., the end goal) will look like is necessary to determine whether acquisition has occurred.

Several guidelines exist for determining on a caseby-case basis what constitutes the end of acquisition. First and foremost, acquisition always ends with the accurate performance (i.e., with few to no errors) of a given behavior. Behavior that is frequently incorrect should not yet be considered an acquired skill. Accuracy implies that a behavior matches the expected form (i.e., shape or topography) of the desired response. During the transition state of acquisition, several approximations or iterations of appropriate behavior may occur before an individual “acquires” a particular new skill. For example, infants typically make vocal approximations of conventional language prior to the production of accurate spoken language forms (e.g., “us at” for the question, “what's that”). While the infant's early vocalizations may be effective in communicating with parents, in the typically developing infant, these vocal approximations are interim steps toward accurate speech production and do not mean that the corresponding appropriate words have been acquired. To carry this example further, within the context of the acquisition of speech, grunting and pointing (another early means of expressive communication) are not equivalent to acquired speech, even though both may have communicative intent. Few would suggest that an infant with this pattern of vocalizations has acquired spoken language. Similarly, few would argue that a student who says 2 + 2 = 5 (a close approximation of the appropriate response) has acquired basic addition skills. In short, accuracy is implicit to acquisition.

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