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UBC Theses and Dissertations

"Errorless" discrimination of reversed letters by children Groves, Muriel Kathleen


The purpose of this project was to devise a method to teach preschool children to discriminate between the letters b and d quickly and with a minimum of errors. In the two pilot studies a simultaneous discrimination task was employed with one letter serving as S+ and one as S-. Children who did not reach criterion during a pretest matching-to-sample task involving the letters b and d served as Ss. During training trials the children were reinforced with candy after each correct response. In both studies control Ss received the final form of the letter stimuli throughout the training trials. For the progressive Ss in the first experiment, the circular part of the negative letter was initially absent and then was introduced gradually over trials. None of the progressive or control Ss acquired the b-d discrimination in this experiment. In the second study three-dimensional letters were used. For the progressive Ss the upright negative letter initially was set so that the circular part of the letter was perpendicular to the front of the body of the S, who was seated facing the letters. The circular part of the letter pointed toward the S. Then, over trials, the negative letter was rotated gradually around its vertical axis until the circular part of the letter was parallel to the body of the S. The circular part of the positive letter always was parallel to the front of the S. Thus in the final step of fading the circular parts of the positive and negative letters were parallel to the S and were facing in an opposite left-right direction. In the second study one of the eight control Ss and four of the seven progressive Ss reached criterion. The majority of the progressive Ss who reached criterion made a number of errors. It was suggested that one possible reason for the lack of the success of the pilot studies was that the fading of the S- letter was not done in a manner which was very "relevant" to the final left-right discrimination. In other words, the steps in the fading sequence did not, through a kind of successive approximations approach, ensure that the behaviour of the child would come gradually under the control of the directionality of the letters. In the principal experiment an attempt was made to devise a fading sequence which would be more "relevant" to the final left-right discrimination. This fading sequence was compared with a control procedure in which the final forms of the letters were used throughout the trials. Subjects who did not reach criterion on the baseline matching-to-sample trials with the letters b-d were assigned to the progressive or control groups. The progressive Ss first received a series of matching-to-sample trials involving arrows pointing either to the left or right. Those who reached criterion on the arrow stimuli received a fading program involving a gradual progression from arrows to final letter-forms. The Ss who did not reach criterion on the arrow series received matching trials involving simultaneously moving arrows. The arrows were moved vertically and then horizontally. The distance of the horizontal movement was reduced gradually until the arrows were stationary. The Ss then received the fading sequence from stationary arrows to final letter-forms. Eight of the nine progressive Ss reached criterion on the b-d discrimination. Seven of the progressive Ss who reached criterion responded correctly on more than 90 percent of the trials while the eighth S was correct on 77 percent of the trials. Only one of the nine control Ss reached criterion. All Ss reaching criterion on the b-d discrimination successfully transferred to a p-q discrimination. The results of these experiments indicate that many preschool children do not learn to discriminate between the reversed letters b and d under a differential reinforcement procedure. However, the majority of such children learn to make this discrimination with no or few errors when they receive a fading sequence which is "relevant" to the final discrimination.

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