Bioenergetics Effects on Perception and Cognition

Previous research has shown that perception of walkable distances is scaled to some form of energy. For instance, people perceive hills to be steeper when encumbered and the energetic cost of climbing would be higher, and likewise when fatigued and less energy is available for climbing. Until recently, the form of this energy had not been defined, measured, or manipulated. The present experiments examine the role of bioenergeticsthe transfer and flow of energy within and organism and between an organism and the environment-in human perception and cognition, and establish that both have direct, concrete links to physiology. Manipulations of glucose, the primary fuel for physical activity and the only fuel usable by the brain, were used to demonstrate a physiological definition for this energy concept. In addition, individual differences in bioenergetic factors such as fatigue, fitness, and a number of direct indicators of physiological state were assessed and shown to predict variability among individuals in perceptual scaling. The experiments in this thesis support the hypothesis that bioenergetic resource limitations are evident in human perception and cognition. First, cognitive performance is dependent on current blood glucose levels, as opposed to expected future changes in blood glucose. Second, visual perception of spatial layout for walkable distances is scaled by the bioenergetic cost of an action and both the current and expected future bioenergetic state of the perceiver. Manipulations of bioenergetic state that increase available energy and/or result in enhanced physical performance through other means cause a compression of walkable distances by increasing the bioenergetic scale. Alternately, manipulations that do the reverse will cause an expansion of walkable iii distances by decreasing the bioenergetic scale. In addition, individual differences in physiology that indicate differences in energy availability or different bioenergetic consequences of an action will likewise change the bioenergetic scale, and cause compression or expansion of walkable distances.

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