William F. Hawkins

The validity of the human figure drawings with disturbed and normal children

Abstract This study was an attempt to replicate the validity study by Koppitz (1966) of 30 emotional indicators in HFDs of children age five through 12. A comparison of HFDs by 72 disturbed children and 80 normal school children resulted in significant differences on nine emotional indicators. The results also supported Koppitzs notion that emotional indicators occur more often in HFDs of disturbed children. However the finding is misleading since the number of indicators cannot adequately differentiate between disturbed and normal groups. Her hypothesis that two or more items are valid emotional indicators is untenable.

REACTION SPEED AS A FUNCTION OF STIMULUS INTENSITY IN NORMALS AND RETARDATES.

The reaction times of retardates and normals were compared as a function of intensity of the reaction signal. Three intensity levels of a 1000-cycle tone were used: 5, 15, and 25 db above threshold. Each S was presented all tones in a completely counterbalanced order. The results revealed that both intelligence groups reacted faster with each increase in intensity of the signal. Since no significant interactions emerged, it cannot be concluded that the groups benefited differentially from increases in intensity of reaction signal. It is suggested that retardates may have a sensory set whereas normals have a motor set in the reaction time task.

Extinction and disinhibition as a function of reinforcement schedule with severely retarded children

Abstract This study was concerned with the effects of partial reinforcement upon extinction and disinhibition of an instrumental response with severely retarded children. The S s were randomly assigned to four groups, each receiving a different schedule of reinforcement—100, 75, 50, or 25%. Reinforcements were distributed randomly over 100 bar-pulling responses. In keeping with the results of other investigations, resistance to extinction was found to be inversely related to the percentage of reinforced trials during acquisition. The same relationship was found to hold with respect to disinhibition.

Effect of Duration of Warning Signal on Reaction Times of Mental Defectives

Two groups of retardates were tested on a reaction time (RT) task. For one group, the warning signal came on and remained for the entire preparatory interval (PI) (filled condition). For the other, the warning signal appeared for 1.5 sec. at the beginning of the PI (unfilled condition). The PIs were 2, 4, 8, and 12 sec. Twenty-six trials were given at each PI. The unfilled condition produced faster RTs than the filled condition. The main effects of PI were also significant. Results are compared and contrasted with those of a similar study.

Stimulus-response durations in paired-associates learning

This study was conducted for the purpose of determining, whether stimulus-response duration, independent of distribution of practice is related to learning of verbal paired associates. Both stimulus-response duration and inter-item interval were varied. lt was concluded that stimulus-response time per se does slightly affect learning, but that distribution produces a more substantial effect.