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UBC Theses and Dissertations

An investigation of the relationship between thirst and speed of perceptual recognition Dunfield, Neil Marvin


This experiment was undertaken to investigate the effect of thirst upon speed of perceptual recognition of thirst satisfying objects. Recent interest in the aspects of perception which may function adaptively has led to many experiments attempting to uncover the relations between perception and motivation. This interest has centered around the distorting and selective influence of motivation upon perception. One aspect of the selective function of motivation is its effect upon the speed of perceptual recognition of need related objects. It was in this respect that the effect of need on perception was investigated in the present experiment. A significant limitation in much of past experimentation in this field has been the use of 'marginal' stimuli by investigators. 'Marginal' stimuli are stimulating situations in which the presented stimuli are either fleeting, blurred, or actually objectively lacking. It was felt that all perceptual stimuli are not of this sort and that to generalize from these limited experiments using 'marginal' stimuli, to all forms of perceptual situations, is unwarranted by fact. The present experiment involved stimuli which were more highly structured than had hitherto been used. The purpose of the experiment was to determine if, as had been postulated by other experimenters, the existence of an organic need would decrease the time of perceptual recognition of objects related to the satisfaction of that need. The need investigated was thirst: need for water. The technique used to induce thirst in the 30 subjects which consituted the experimental group, was to feed them peanut-butter before the experiment. The 30 subjects in the control group did not receive the peanut-butter. All subjects, subsequent to experimental testing, were asked to fill out a self-rating on a subjective five point scale of felt thirst. The stimulating situation involved the use of ten puzzle-picture cards. Within each card had been hidden one object. Five of these hidden objects were neutral relative to the need being tested. The other five objects were related to the satisfaction of the prevailing induced need. The type of thirst related objects used, had previously been determined through the use of an association technique applied to a class of undergraduate psychology students. The experiment yielded the following results: 1. The experimental group rated themselves as significantly more thirsty on the self administered scale of felt thirst than did the control group. Hence, we could analyze the remaining data confident that a differential degree of thirst had been established between the control and experimental groups. 2. It was statistically indicated that neither the control or the experimental group demonstrated a correlation between speed on the need cards and speed on the neutral cards. This indicated that if the induced need was effecting perceptual recognition, it was doing so for only one type of object: need or neutral. Consideration of nearly equivalent amounts of correlation tendencies in the control and experimental groups, throws some doubt on the original hypothesis the need will effect the recognition of need related objects. 3. The application of distribution free statistical methods to the results of the individual cards showed that there was no significant difference between the recognition speed of the control and experimental group on any single card. 4. These results did not lend support to the hypothesis that need will effect the speed of perceptual recognition of objects related to the satisfaction of that need. Within the limitations of the experimental technique, this experiment did not support the general hypothesis that need effects perception in terms of perceptual recognition time.

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