The number of ways to label a structure

It has been observed that the number of different ways in which a graph withp points can be labelled isp! divided by the number of symmetries, and that this holds regardless of the species of structure at hand. In this note, a simple group-theoretic proof is provided.This work was supported by Grant MH 10834 from the National Institute of Mental Health.     

The effect of prior recall on multiple response recognition

Certain investigators have found that recognition is impaired when a recall test is interpolated during the retention interval. One possible explanation of this finding is that interpolated recall leads subjects to employ a more stringent recognition criterion. In the two experiments reported here, the influence of the recognition criterion was eliminated by using a multiple-response test requiring subjects to rank a recognition list consisting of old and new items. Nevertheless recall impaired subsequent recognition in both experiments, the effect being most marked for lowly ranked items. The recognition test in the first experiment was carried out in two stages. This made possible a direct examination of whether recall has an effect on the recognition criterion. No evidence for such an effect was obtained. Other ways in which recall may affect the recognition criterion are discussed.     

Averaged occipital responses to stimulation of sites in the upper and lower halves of the retina

Averaged responses of the occipital lobes to flashes imposed along the midline of the upper part of the retina are larger and of shorter latency than responses to flashes imposed on the lower retina. Since reaction times also are shorter when the upper retina is stimulated, this study provides further evidence for the generalization that reaction time varies inversely with amplitude and directly with latency of the evoked response.     

An investigation of several parameters of the horizontal-vertical illusion

Length of standard line, degrees of lateral separation of H and V stimuli, and which line served as standard or comparison stimulus were systematically varied in a 4 by 3 by 2 factorial design on the horizontal-vertical illusion. When illusion affects were averaged under H- and V-standard conditions, a negative relationship obtained between magnitude of illusion and length of line. With. vertical as standard, the illusion increased as a function of lateral separation of stimuli, but decreased with horizontal as standard. These differential trends for H- and V-standard conditions contributed to the unsystematic relationship between the size of the illusion and progressive displacement of H and V lines. The illusion curves for three lengths of standard line across degrees of lateral separation were similar. The findings are viewed as incompatible with explanations of the H-V illusion involving the so-called “error of the standard.”