Concurrent performances: a baseline for the study of reinforcement magnitude

When a pigeon's pecking on a single key was reinforced by a variable-interval (VI) schedule of reinforcement, the rate of pecking was insensitive to changes in the duration of reinforcement from 3 to 6 sec. When, however, the pigeon's pecking on each of two keys was concurrently reinforced by two independent VI schedules, one for each key, the rate of pecking was directly proportional to the duration of reinforcement.     

A note on the standard length of a test

This paper describes a relationship between the variance-covariance matrix of test items and Woodbury's concept of the standard length of a test. An index of item-test relationship is described in standard length terms. The sum of these indices for the items in a test is equal to the square of Jackson's coefficient of sensitivity.     

SOCIETAL MEMBERSHIP,SCORE STATUS,AND GAME BEHAVIOR

Appartenance sociale, bilan relatif des gains acquis et comportement de jeu. Analyse phénoménologique. — Etude des preférénces, des raisons et du comportement reel de choix de sujets belges et américains dans une tâche qui laisse la possibilité de se comporter coopérativement ou compétitivement. La tâche utilisée est un jeu à somme non-nulle dont la matrice est structuréd de telle sorte que l'on puisse différencier deux objectifs parmi trois possibles : maximiser son propre gain (ou le gain conjoint des deux partenaires) ou bien maximiser la différence entre son propre gain et celui de l'autre. Les Auteurs ont comparé 15 dyades de sujets belges et 15 dyades de sujets américains, jouant en 100 essais. Les résultats montrent que le choix réel des sujets est trés semblable d'une culture à l'autre et que, dans chaque culture, il varie selon que les gains déjà acquis par un sujet sont supérieurs, inférieurs ou égaux à ceux du partenaire, au moment du choix. Enfin, on note que, bien qu'aucune différence marquée n'apparaisse dans le comportement réel, il y a des différences sensibles d'une culture à l'autre dans les raisons invoquées par les sujets pour justifier leurs préférences : ces différences sont encore plus apparentes si on tient également compte de l'état relatif des gains déjà acquis par un sujet par rapport à son partenaire. En général, les sujets belges ont tendance à justifier leur préférence pour la compétition par des raisons de compétition; les sujets américains, surtout quand ils ont l'avantage, par des raisons relatives à leur gain personnel. Cette dernière réaction est “irrationnelle” dans la présente tâche puisque la préférence pour une attitude coopérative permet de maximiser son propre gain.     

The effect of abnormal displacement of the retinal image during eye movements

The displacement of the images on the retina that results from a turning of the eye does not lead to an apparent motion of what is seen, It has been generally assumed that this is due to a compensating process which takes eye movement into account and serves to discount those image displacements that result from eye movements, It follows from this view that an abnormal image displacement, that is, an image displacement that is larger or smaller than the causing eye movement would warrant, should lead to an experienced displacement of the target. Abnormal image displacement was produced by placing the eye in the converging or diverging bundle of rays from a point source that form behind a strong positive lens; this arrangement yielded a disc-shaped image, the projection of the pupil onto the retina, which displaced abnormally during eye movements. By changing the position of the eye along the axis of the lens in relation to the crossing point of the bundle, the degree to which the displacement was abnormal could be varied, For various displacement rates ranging from 25% to 120 and 400% of normal, abnormal displacements produced by incidental eye movements remained unnoticed, Only where eye movements were intentional did some of our Ss report shifts of the perceived image. It is suggested that the organism copes with the image displacement resulting from the ever-present incidental eye movements not by compensation but by ignoring them.     

Binocular summation in the perception of form at brief durations

Visual form identification at brief durations was studied under: (a) monocular presentation; (b) dichopic presentation where the same form was presented successively on noncorresponding areas; and (c) dichopic presentation where the same form was presented on corresponding areas simultaneously and successively. Form identification for noncorresponding area dichopic presentation was at the level to be expected from 2independent chances to perceive. Both simultaneous and successive dichopic presentation on corresponding areas gave identification accuracy significantly above the level predicted by the assumption of independence. However, the binocular summation was not complete. When the same amount of energy entering the visual system in a binocular presentation was given in a monocular stimulation, the latter condition gave significantly better identification.