The Effect of Experimentally Induced Changes in Metabolism on Perceptual Measures of Metabolic Efficiency

Abstract

Most psychologists will go along with the assumption that every behavioral or perceptual alteration in a person is accompanied by a change in the neural substrate. Assuming that the magnitude of these changes in the psychic and physical realms are quantitatively comparable, it follows that a relatively large psychological alteration is accompanied by a relatively large physiological change, and vice versa. For example, a large perceptual distortion produced by a figural after-effects technique (2) would be accompanied by a relatively extensive change in the neural substrate while a smaller distortion would mean a smaller change in the neural substrate. Such reasoning can also be applied to individual differences. Suppose one man obtains a large figural after-effect from a given satiation technique while another obtains a small one; the satiation must have produced a greater change in the nervous system of the former than of the latter. If this daerence occurs under identical stimulating conditions, it must be due to individual diEerence in modifiability. The first man has a more modifiable neural substrate than the second. Elsewhere (5,7) we have argued that any change in the neural substrate can be considered a metabolic change, and that a person who is very modifiable on perceptual measures such as a figural after-eflect test is metabolically egcient, while a less moditiable person is metabolically less efficient. Previous studies have shown a milinear relation between various over-all metabolic measures and perceptual distortability, in that Ss falling in the normal range on such measures as BMR or thyroid activity have a greater perceptual modifiability than Ss either below or above the normal range (4, 5, 7). The present studies were undertaken to see whether it is possible to produce changes in perceptual modhability by artificially changing metabolism in a group of normal Ss, with the expectation that a change in general body metabolism would be reflected in brain metabolism and hence in the perceptual rneasures. Three perceptual measures were employed: kinesthetic figural after-effect, ambiguous figure reversal, and a perceptual association. For the first, the kinesthetic figural after-effect test, blindfolded Ss &st found a width on a variable bar which felt just as wide as a standard bar, then rubbed inspection bars for one