Detectability gradients as a function of target location

We examined the ability to detect a specified visual pattern (a target) in a randomly selected location when it was briefly presented with 11 other spatially distributed nontarget patterns and also when it was presented by itself for the same duration (50 msec) on a background of visual noise. Two experiments were designed to measure target detectability as a function of its location in the visual field where all possible target locations were equidistant from the fovea. A right visual field detection superiority was obtained in both experiments. In addition, highly significant detectability differences were observed within the right and left visual fields in both experiments. The origin of these detectability differences are interpreted in terms of parallel and serial processing mechanisms.     

Angular induction as a function of contact and target orientation

The Poggendorff effect is seen as misalignment of two obliques, or misprojection of one, when the obliques are placed outside a set of parallel lines. To understand better the mechanisms behind this effect, the orientation of the lines which are normally parallel was systematically manipulated. The results indicate that projection bias is affected by the orientation of either line, is at a minimum where the line is orthogonal to the oblique, and is maximal at small angles. This is in line with classic theories which attribute the illusion to misperception of angular size. However, such explanations presuppose that in order to be effective the induction line must be proximal to the oblique so that an angle can be formed. Results are reported which show that the angle formed by the oblique and a line placed at a distance from the oblique, serving as the target of the projection, follows an angular rule of effectiveness similar to what is seen when the line is placed directly in contact with the oblique. The underlying process is described as 'angular induction'.     

Deceit as a function of sex of subject and target person

Thirty male and female undergraduates were run in same- and opposite-sex pairs to determine if the extent of experimentally sanctioned deceit would be influenced by sex pairings and potential for harm to another's self-esteem. Ss, who all believed they were playing the role of a teacher in a learning experiment, were instructed to provide false feedback (lie) at least three times during 30 trials to a learner, the other S. Consistent with hypotheses derived from a consideration of the potential harm to another's self-esteem and a suggested norm of white lying, perceived relative importance of male and female sex roles, and greater female concern for the social welfare of others, it was found that white lies occurred significantly more often than lies, that males were significantly more likely to give false feedback than females, that females were the target of false feedback significantly more often than males, and that the interaction between sex of S and sex of target person was also significant in that males lied to females more than any other sex pairing.This research was partially supported by the New Mexico Highlands University Institute of Scientific Research. A brief version of this report was presented at the Rocky Mountain Psychological Association meeting, Denver, May, 1974.     

Perceived target displacement as a function of field movement and asymmetry

In two experiments induced movement of an object was produced to demonstrate that movement of the background influences the perceived localization of the object in space. The Roelofs (asymmetry) effect could be used to explain only part of the shift in localization in Experiment1. The asymmetry effect was excluded from Experiment2 by the procedure employed. It was concluded that the Roelofs effect is a sufficient, but not necessary, condition for the effects of induced movement to occur, and that relative displacement of the target and background plays an important part in the illusion. Furthermore, it was shown that the effects of induced movement can occur even when the border of the background remains stationary.     

Goal-driven modulation as a function of time in saccadic target selection

Four experiments were performed to investigate the contribution of goal-driven modulation in saccadic target selection as a function of time. Observers were required to make an eye movement to a prespecified target that was concurrently presented with multiple nontargets and possibly one distractor. Target and distractor were defined in different dimensions (orientation dimension and colour dimension in Experiment 1), or were both defined in the same dimension (i.e., both defined in the orientation dimension in Experiment 2, or both defined in the colour dimension in Experiments 3 and 4). The identities of target and distractor were switched over conditions. Speed–accuracy functions were computed to examine the full time course of selection in each condition. There were three major results. First, the ability to exert goal-driven control increased as a function of response latency. Second, this ability depended on the specific target–distractor combination, yet was not a function of whether target and distractor were defined within or across dimensions. Third, goal-driven control was available earlier when target and distractor were dissimilar than when they were similar. It was concluded that the influence of goal-driven control in visual selection is not all or none, but is of a continuous nature.     

Fitts' law as a function of system dynamics and target uncertainty

Fins' law was found to hold for discrete movements executed by subjects controlling the velocity of a cursor with a control stick The slope of movement time versus index of difficulty was approximately twice as large as for a comparable position control system. Target uncertainty also increased the slope of total time versus index of difficulty, and this effect is interpreted in terms of adaptive tuning of the human movement system.