liighly junior high school studenls made monocular comparisons of standard and variable apertures through collimating lenses in a dark room. Placement of paired targets was varied in a vertical arc with 10 combinations of elevations at 10°, 30°, 50°, 70°, and 90° to the horizontal. When the standard was the lower target, size and distance discriminations were both distorted (p < .001) in a comparable illusory direction (lower target seen as larger and nearer). No illusion was obtained for size or distance discriminations when the standard target was in the upper position.

The effectiveness of television distortion as a negative reinforcer was analyzed. Contingency arrangements involving television distortion were found to be capable of (a) accelerating the work rate of a naive, mildly retarded subject on a simulated production-line task involving card-sorting, and (b) reducing gross hyperactivity of a mildly retarded subject. An escape-avoidance contingency was arranged for the production-line behavior of the first subject and a punishment contingency for the hyperactive behavior of the second subject. Television distortion appears to be an effective and practical negative reinforcer for use in behavior modification.

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Determinations of illuminance preference of rats have been made by Lockard (1962Lockard ( , 1963 and by Johnson (1%4, 1965). Using bar pressing and locomotor response measures respectively, data obtained by these investigators differ in support of a preference hypothesis (Lockard & Lockard, 1964) suggesting a range of dim illuminations which have greater preference value than darkness. A confounding issue is the reinforcement value of stimulus change which, as Johnson (1965, p. 541) noted, varies in specific relationship to apparatus and procedure used; the effect of the variable of illumination change is apparently reduced with a locomotor response and increased with a bar-press response.The issue of organismic need for stimulus change is generally related to the theories stemming from sensory deprivation (Brownfield, 1965) and perceptual organization by active involvement (Gibson, 1966). As SoUberger (1965, p. 26) states, the animal in the field as well as man himself "builds his own environment to such an extent that it is truly an extension of himself. "The primary objective was to determine the rat's ability to place himself on a circadian cycle of light and dark. According to Lockard (1963) "It would not be unreasonable to expect self-produced periods of light and dark to bear an orderly relationship to the circadian locomotor periodicity characteristic of many rodents. Were this so, the motivation for bar pressing for light would be associated with the maintenance of a rhythmic system and the light begins to resemble a 'primary need' more than a mere sensory change [po 522).".. -- Subject. The S was a male hooded rat (four months old) of the Long Evans strain. Prior to this study S was maintained in an individual cage on a constant light schedule of 12 h dark and 12 h light (1-5 ft"i: depending on location of meter probe).Apparatus. The cage housing was a light-tight wooden box (75 x 75 x 87 cm) with 10 W incandescent lamps mounted on the ceiling with a Fresnel lens and a white translucent, vinyl plastic sheet suspended under the lamps as diffusers. A fan and baffled intake and exhaust ports allowed for adequate ventilation. Room temperature (mean = 72 deg F, ± I deg F) and humidity (mean = 42.2 deg RH, SD 4.7 deg RH) were con· trolled and measured intermittently to assure no daily periodicity.On the floor of the wooden surround and 66 em under the diffusers a transparent plastic cage (38 x 25 x 15 cm) was fitted with two levers located at opposite ends of the box 5 cm from the floor. Any bar press altered the light (1-2 ft-c) to dark or the reverse by use of a ratchet relay. A capacative-discharge circuit prevented bar holding artifacts.A 20 pen event recorder was used as a cumulative counter and a milliammeter recorder was used to detect light alterations within the chamber as sensed by a Delco LDR-25 photoresistive cell installed as one arm of a Wheatstone bridge circuit and located on the floor of the surround next to the cage. The purpose of the milliammeter recording was to facilitate data analysi...