The relative difficulty of three position discriminations for persons with severe to profound developmental disabilities

Abstract

The Assessment of Basic Learning Abilities (ABLA) test, developed by Kerr, Meyerson, and Flora (1977) assesses the ease or difficulty with which individuals with developmental disabilities are able to learn a simple imitation and five two-choice discrimination tasks. During ABLA Level 2, referred to as a position discrimination task, the client is presented with a yellow can always on the left and a smaller red box always on the right. The client is required to place an irregularly shaped piece of foam into the container on the left (the yellow can) for a correct response. With this task a client can learn to make a correct response based on position, colour, shape, or size cues, or some combination of these. The current study evaluated the relative difficulty of ABLA Level 2 and two additional types of position discriminations. The first type of task was similar to ABLA Level 2, except that it used identical containers, and thus contained both relative and absolute position cues (the REAB task), but not shape, colour, or size cues. The second type of task was similar to ABLA Level 2; however, it incorporated identical containers that varied in their absolute positions, which required a relative position discrimination to arrive at the correct response (the RE task). In Experiment 1, I used an alternating-treatments design with replication within and across three participants who passed ABLA Level 2 but failed all higher levels, to examine how many trials were required to master tasks analogous to ABLA Level 2, versus REAB tasks, versus RE tasks. In Experiment 2, I used a within-subject design with replication across three participants to further clarify the relative difficulty of the three position discrimination tasks, and to determine whether correct container location (i.e. left versus right) can influence the difficulty of learning the tasks. The results demonstrated that there was no consistent difference in difficulty between the three types of tasks, and the difficulties experienced by P1 and P2 can be accounted for entirely by an interaction between the right-left location of the correct response and handedness.