正常和弱视者立体和形状视觉感知时间的差异

在速示器,以随机点立体图对为刺激,测量了正常和弱视者的立体视和形状视感知时间。实验表明:正常被试需要大约100ms感知深度,110ms或更长时间感知形状。这二种感知时间与刺激视差的种类和大小无关。弱视者需要比正常人较长的时间达到立体和形状的视感知。这二种感知时间的差别,弱视者也大于正常人。视锐度和立体视范围均恢复到正常的弱视者,以上二种感知时间,可以达到正常人范围,也可能显著地大于正常人。     

Social position and competition in laboratory rats.

Two experiments with rats as subjects are described, which control for social position, i.e., relative dominance/submission, in an appetitive social learning-performance setting. The results indicate that animals that perform quite effectively when alone exhibit significantly reduced levels of responding when placed into a social environment. The severity of the response decrement is, at least in part, a function of the relative social position of the subjects involved. A dominant male made few responses when paired with another dominant male. Yet, a dominant subject made even fewer responses when paired with a submissive subject, which bar pressed at approximately half the individual level. These findings are interpreted as suggesting that social position, with its accompanying characteristic form of aggression, is an important determinant of performance in a social learning environment.     

Magnitude of negative reinforcement and resistance to extinction

In the first experiment rats experienced large or small magnitude of negative reinforcement (shock reduction) in a straight alley. Half of the subjects in each magnitude group received continuous reinforcement, and the other half received a 50% partial reinforcement schedule (nonreinforcement consisting of no shock reduction in the goal box). In extinction the groups were ordered: large partial > small-partial > small-continuous > large-continuous. In the second experiment rats received large, small and nonreinforcement in various sequences using the runway-negative reinforcement procedure and were ordered: SNL>LNL>SNL>LNS in resistance to extinction (letters represent the magnitudes in the sequence experienced in acquisition). The results of these experiments indicate a commality between positive and negative reinforcement with respect to behavioral phenomena and theoretical accounts of those phenomena.     

Degree of training and the novelty transfer effect

Four groups of 40 Ss were given transfer tests following 2.4, 6, or 8 14-trial blocks of paired-associate training with unequal stimulus frequencies and then retested after a further training period in which the same compound stimuli were presented at equal frequencies. The novelty effect, in which Ss respond to new combinations of training components by giving the response associated with the least frequent component, was obtained in every transfer test. It was concluded that the novelty effect is a mode of responding that is produced by differential frequencies during early learning and which, once adopted, is retained by Ss regardless of whether the frequency differential is maintained.     

An automated odor test for rats

The odor-testing apparatus described consists of a circular open-field area opening into four glass tubes, each with an odor source at the far end. When a rat is introduced, each tube is blocked by a grid; when the rat has touched each grid (sampled each odor), the tubes automatically open and recording of preference behavior starts. Two measures of preference are recorded by a photocell outside each tube, the number of visits and the time spent near the odor source. A uniformity test with food odor in all tubes showed that the apparatus did not promote position bias. In two separate sensitivity tests, one with food odor and one with estrous female urine odor, male rats significantly preferred an attractive odor in one tube to odorless controls. The apparatus yields relatively sensitive and reliable odor preference determinations by ensuring sampling of each odor before data are recorded and by eliminating visual, auditory and gustatory cues.     

Expectancy confirmed again: A computer investigation of expectancy theory

A computerized attempt to replicate Aronson and Carlsmith's test of expectancy theory was conducted. Generally, subjects performed consistent with their expectancy, although the effect of expectancy was strongly attentuated by an overall achievement orientation. The results contradict the hypotheses that experimenter bias, demand characteristics, or differential recall of performance mediate the effects of expectancy upon performance.     

A scale for the psychological magnitude of number

A scale of the “psychological magnitude” of number was constructed from similarity ratings of the 45 number pairs that can be obtained from a set of 10 integers. A nonmetric analysis of these similarity ratings showed that “psychological number” was a power function of number.