In defence of a ratio model for movement detection at threshold

Sutherland (1961) proposed that the detection of motion might depend upon the ratios of firings in cells sensitive to movement in opposite directions. Sekuler and his collaborators have argued that the notion of a ratio mechanism at threshold is wrong. The findings and arguments upon which this conclusion was based are challenged, an explicit model is described which provides an account of data previously held to be inconsistent with a ratio model, and an experiment is reported which provides unequivocal support for the ratio model and whose findings are inconsistent with the predictions from Sekuler's “independence” model.     

Studies in social influence: V. Minority influence and conversion behavior in a perceptual task

The effects of influence attempts by a majority and by a minority were examined on both a manifest response level and a latent perceptual level. Female subjects were exposed to a series of blue slides that were consistently labeled as green by a female confederate. The confederate was presented as a member of either a majority or a minority. On each trial, subjects were required to indicate the color of the slide presented and the color of the afterimage perceived on a white screen following removal of the slide. It was predicted that (a) the subject's judgment of the chromatic afterimage would be modified when the influence agent represented a minority, and (b) this modification will be more pronounced when the source of influence is absent than when it is present. The results supported the prediction in both the main study and its replication.     

Some determinants of task preference and the desire for information about the self

This research examined the influence of task difficulty and diagnosticity (ability information) on task choice and preference. It was found that males preferred diagnostic over non-diagnostic tasks, but among females significant preferences along this variable were not exhibited. Furthermore, the desire to obtain ability-relevant information decreased as a function of prior knowledge about one's ability. Both high and low ability self-perceptions, induced through prior experiences of success and failure, decreased the attraction toward diagnostic in formation. There was no indication that individuals with high ability self-concepts are especially avoidant of further ability-relevant information, as recent literature has suggested. In addition, and contrary to prior findings, difficult tasks were most preferred rather than easy or intermediate tasks, given that diagnosticity is held constant.     

Field-dependence,extraversion, Eysenck and autarky

The research literature was examined with regard to relationships between Field-dependence and Extraversion. Eysenck's contention that the two variables are significantly related to an extent justifying the use of causal hypotheses based on extraversion theory to account for field-dependent behavior was not supported.     

Apple II/FIRST system control of electrical brain stimulation in the rabbit

An Apple II/FIRST system has been developed to control classical conditioning experiments, collect analog data, and extract dependent variable measures of conditioning from uniphasic (Scandrett & Gormezano, 1980) and multiphasic (Johnson, 1981) response signals. The present paper details the development of an electrical brain stimulation system as a peripheral device to the Apple II/FIRST system. In addition, data are presented that document the capabilities of the EBS system to concurrently stimulate up to eight animals while values along the dimension of each of four stimulation parameters are manipulated by a program written in FIRST. In our judgment, the EBS system has a number of advantages over currently available commercial stimulators, including cost, number of sites that can be independently stimulated, and availability of complete software control.     

Studies in social influence VI: Is Lenin orange or red? Imagery and social influence

Two experiments dealing with the effects of a majority or a minority source influence, solely on the recognition of a portrait, let us study the generalization of the influence to a portrait symbolically linked to a colour. According to the theory of conversion, the bringing into play of the validation process of the stimulus when the source is a minority should allow such a generalization cognitive association. When the source is a majority, a social comparison process should lead to compliance about the portrait, without any cognitive investigation of the whole stimulus. In the first experiment, four slides were shown successively using material similar to Luchins' (1945) and progressively drawing the portrait of Lenin, with a red-orange background for each phase. The dependant variables are: (1) the drawing, (2) the colour of the background, (3) the after-image. On the two last slides for which the answer ‘Lenin’ is given by the source, changes towards red (and the complementary colour green), in the absence of the source under the minority influence, and changes towards orange under majority influence in the absence of the source are registered. Moreoever, the most significant changes of the colour judgment are due to the subjects who refuse to answer ‘Lenin’ during the interaction. In the second experiment, only the fourth slide, on which Lenin's portrait completely appears is shown. The subjects submitted to majority influence answer ‘Lenin’ more than the control group does, only in the presence of the source and change their judgment on the colour of the after-image towards the complementary of orange in the absence of the source. When the source is a minority a sinificant effect towards the red and its complementary colour is shown.     

A look at social support patterns

The issue of how to provide support for patients with a life-threatening illness continues to be a problem for pastors and chaplains. The authors discuss the significance and reasons for looking at the present day social support patterns as an unnatural problem. Unless the unnatural nature of support in the modern medical setting is understood pastors and chaplains can miss the target on answering the question of how to provide support. The authors conclude the article by addressing this question from the position of reserving the unnatural nature of providing support.Dr. Bergen is Professor of Psychiatry, Dartmouth Medical School, Hanover, NH 03755. Dr. Nelson is affiliated with the Chaplain Service, Veterans Administration Center, White River Junction, VT 05001 and Assistant Professor of Clinical Psychiatry, Dartmouth Medical School.