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In 4 separate experiments albino rats were allowed to stabilize in rate on an activity (eating, drinking, light-exposure, or running), after which they were deprived of that activity for a time ranging from 2 to 8 days for different groups. The intent of the methodology was to apply the classical test for “drive”—increased comsummatory behavior following deprivation—to 4 different response measures and to examine in detail the time-course of deficit elimination. Food and water deficits were replaced in an orderly fashion requiring about 3 wk. for completion. Deficits of running activity were not replaced. Compensation for deficits of light was intermediate, showing a little replacement on the first day after deprivation, but no clear evidence of replacement thereafter.

Summary.-Animal research has adopted no standards for lighting practices. One consequence is that light intensity is either unreported or often improperly measured, even in experiments primarily concerned with light. This article tells how to measure and report light intensity and discusses the relative advantages of different kinds of light sources and lighting geometry. Roughly a hundred articles about the motivating properties of light have been published in the last decade. In a few of these, light intensity was reported in a helpful way (e.g., Stewart, 1960). But the vast majority of articles reveal a most casual concern for the stim~ilus whose effects were allegedly investigated. One often finds either a conspic~io~is absence of statements about lighting geometry and light intensity or an amateur discussion of irrelevancies. Also common is a meaningless confusion in which a photometric term is paired with an incompatible unit, as illustrated in a paper (reference withheld) stating "The intensity of illumination was one millilambert." The net result of chis variety of shoddy measurement and reporting practices is to make private what should have been public, namely, the physical value of the stimulus. Since it is quite clear that different light intensities produce different behavioral effects (Lockard, 1963), the "location" of the experiment along an easily measured continuum should be divulged. If it is not, the results of the experiment are not anchored to stimulus conditions and merely demonstrate that a particular effect can occur at some unknown and unduplicable combination of conditions. The experiment cannot be fitted into the fabric of scientific knowledge and cannot be replicated; and the results are, therefore, safe from expose if they are a Type I error. Any collection of such studies soon generates apparent but unresolvable inconsistencies, unresolvable because levels of variables other than light intensity are usually in doubt when one compares different studies. The artful reviewer can juggle the discrepancies in a multidimensional private calculus of guesswork, attaching effects to conditions; but this was the experimentalist's job. Had the experimentalist appreciated the rudiments of photometry, subsequent literary efforts could turn from guesswork about treatment effects to informative summarizing. 'The preparation of this paper was made possible by Grant No. HD 00942 from the National Institute of Child Health and Human Development. The content of the paper is largely from Chapter I, Basic Methodology, by J. B. Sidowski and R. B. Lockard, in Experimental Methods and lnstrumen!a!ion in Psychology, edited by J. B. Sidowski, McGrawHill, New York, 1966. The author is grateful to both J. B. Sidowski and the McGrawHill Book Company for their permission to draw upon copyrighted material.

The classical procedure for demonstrating the reinforcing properties of stimulus-change for rats confounds the response-contingent change with the production of dim illumination. This experiment unconfounded the two by providing a response-contingent visual change without a change in the ambient illumination. This “pure” visual change was not reinforcing, whereas a response-contingent change from darkness to dim illumination—the classical procedure—was unambiguously reinforcing. Thus much research purporting to demonstrate reinforcement in rats by “visual change” can be reinterpreted as demonstrating that dim illumination is preferred over darkness.

Various recommendations for modification or maintenance of the widely used Wahmann LC-34 activity wheel are made. These recommendations are based upon considerations of consistency of performance, sanitation, convenience to E, minimizing between-wheel differences, and the elimination of undesirable properties.

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Subjects were required to distinguish between accelerated and constant-velocity motion of targets. For different viewing times, ‘group thresholds’ were more nearly the same when relative acceleration was expressed in terms of total change of velocity during the viewing interval (vv/v) than when in terms of change per unit time (δv/v). This suggests that accelerated motion is identified by comparison of early and late velocities rather than by direct sensing. Also it was shown, through reference to other studies, that it is more difficult to identify gradual change of velocity than to identify instantaneous change or to discriminate between two ongoing motions of different constant velocities.

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Relative sucrose solution intake in 6-bottle tests was studied in rats under conditions of food-, water-, food-and-water-, and non-deprivation, and under conditions in which food was present or absent during testing. Water deprivation was most effective in altering the intake function, but deprivation interacted with the test-food variable to produce changes in the intake functions of food-, and food-and-water deprived Ss.

The replacement properties of a need system (water) and an incentive system (saccharin) were compared following a 6-day period of fluid deprivation. While water deprivation was followed by complete replacement of the water deficit, deprivation of a saccharin solution was followed by substantial over-replacement of the water deficit. This result is interpreted as indicating, an increase in the incentive value of the saccharin solution attributable to deprivation.

Albino rats were presented with one of five pairs of sucrose solution (0–2, 2–4, 4–8, 8–16, 16–32%) for 11 consecutive daily tests of 1 h or 23 h duration. Frequency of preference for the lower concentrations of the pairs was an increasing function of concentration and test duration.

The total night-time activity-wheel running by two sympatric species of mice, P. californicus and P. eremicus, was compared under the same simulated sun and moon cycles. Total running by P. californicus correlated negatively with the nightly duration of moonlight, while that of P. eremicus correlated positively. The results were discussed in terms of a temporal dimension of competitive exclusion.

The reinforcing properties of the brief onset of dim light contingent upon bar-pressing are well established (Kish, 1955; Marx, Henderson, & Roberts, 1955). While current theory tends to attribute the reinforcement to the change in stimulation, it is possible that the absolute luminance produced by the change is important. If this were the case, rats allowed operant control of cage luminance should show a preference for a restricted range. If stimulus change alone governs the operant, no orderly distribution of selected luminances should result. This report describes a pilot study in which rats could regulate cage luminance for long periods of time. Method.-Three female Sprague-Dawley rats were raised in constant light except one, which by chance experienced about one month of a 12-ht. light-dark cycle. An 18-in. diameter light-tight cage had a translucent glass top 12 in. above the floor. An array of 15 incandescent bulbs above the glass top provided 16 different cage luminances from 2 log mL down to -5 log mL in half-log steps; then darkness followed -5 log mL. Luminances were measured from a Macbeth test plate on the cage floor. Opposite the continuously available food and water were 4 levers: Up, Middle, Down, and End. Up increased cage luminance l/z log unit each time pressed; Down similarly decreased it (cf. Stein & Ray, 1959). Middle and End were dummy levers connected only to counters. Rat A was introduced into the apparatus and left undisturbed for 77 days, B for 77 days, and C for 40 days. Resalts.-Table 1 shows the mean daily operant level on each lever

Background The purpose of this study was to determine the effects of participating in a resistance-exercise based circuit training program while adhering to a higher protein diet designed to preserve fat free mass (FFM) during weight loss on body composition and markers of health. Then, in a companion paper, determine if exercise and diet-induced weight loss affect markers of inflammation.