Illusions of size change in dynamic displays

A line of constant width viewed against an expanding or contracting grating appears to become narrower or wider, respectively. This effect was studied using a computer-controlled video system with a motorized zoom lens. The magnitude of the illusory size (width) change with a vertical line did not differ when viewed against a horizontal or an oblique background, and the size change was not due to static size contrast between the line and the background. The illusory narrowing observed with an expanding background was equivalent to the widening observed with a contracting background. The apparent change in the width of lines that actually expanded was consistently underestimated, either on a similarly changing background or when viewed against a gray field. Although the transformation of the background and line produced changes in their perceived distance, this did not occur for a constant line against a transforming background, even though this condition induced the perceived size change.     

Conformity as a function of the consistency of positive self-evaluation with being liked and being right

Insko, Sedlak, and Lipsitz (European Journal of Social Psychology, 1982, 13, 143–167) have presented evidence that agreement effects in p?o?x triads, or semicycles, are at least partially a function of the consistency of positive self-evaluation with being liked and the consistency of positive self-evaluation with being right. Consistent with the Insko et al. balance interpretation of agreement effects, results indicated that conformity in an Asch-type experiment is a joint function of the concern with being liked and the concern with being right. The judgment stimuli were sets of three colors, and the subjects' task was to indicate whether the middle color was more like the color on the left or the color on the right. In the main experiment, subjects conformed more with public than with private responding, and also when they were led to believe that the relationships among the colors were objectively determined rather than undetermined. The first of these two results (in conjunction with the lack of an interaction and the presence of a difference between the public condition and a private camera control condition) was taken as evidence for the concern with being liked. The second finding of a difference between the determined and undetermined conditions was taken as evidence both for the concern with being right and also as indicating that conformity can occur with objective stimuli. Although concepts similar to the concerns with being right and liked have been widely discussed, a review of the literature indicated that the previously presented evidence is not totally convincing.     

A correction to “The retinal reference of the tilt aftereffect” by Coltheart and Cooper

Coltheart and Cooper (1972) reexamined the data of Day and Wade (1969) concerning the retinal or gravitational reference for normalization and the tilt aftereffect. Their analysis contained a factual error concerning the procedure employed in the latter investigation, which is here corrected. Day and Wade did not, however, distinguish between normalization and aftereffect. When this distinction is made, the data from the two studies taken together indicate that deviation of an inspection line from the vertical retinal meridian is not sufficient to produce normalization but does yield a visual tilt aftereffect.     

The representation of uniform motion in vision

For veridical detection of object motion any moving detecting system must allocate motion appropriately between itself and objects in space. A model for such allocation is developed for simplified situations (points of light in uniform motion in a frontoparallel plane). It is proposed that motion of objects is registered and represented successively at four levels within frames of reference that are defined by the detectors themselves or by their movements. The four levels are referred to as retinocentric, orbitocentric, egocentric, and geocentric. Thus the retinocentric signal is combined with that for eye rotation to give an orbitocentric signal, and the left and right orbitocentric signals are combined to give an egocentric representation. Up to the egocentric level, motion representation is angular rather than three-dimensional. The egocentric signal is combined with signals for head and body movement and for egocentric distance to give a geocentric representation. It is argued that although motion perception is always geocentric, relevant registrations also occur at the three earlier levels. The model is applied to various veridical and nonveridical motion phenomena.     

The effect of lateral visual fixation on response latency to verbal and spatial questions

The results of several studies have suggested a relationship between lateral eye movements and contralateral hemispheric activation or ipsilateral inhibition. The present study investigated the effects of lateral and central eye fixation on response latency to verbal and spatial questions. Response latencies for verbal questions were significantly longer when subjects fixated to the left or centrally, as compared to the right. On spatial questions, response latencies were significantly longer in the right fixation condition than in the other conditions. The results indicate that visual fixation ipsilateral to hemispheric activation is related to slower problem solving, and suggest that eye movements during cognitive activity may have functional significance.     

Visual orientation during and after lateral head,body, and trunk tilt

Visual judgments of orientation were investigated during (effect) and after (aftereffect) different body postures. In Experiment 1 four trained Ss made apparent verticality (AV) judgments before and after 2 min in each of seven orientations: head tilt left and right, body tilt left and right, trunk tilt left and right and a control condition with head ’and body upright. The aftereffect was significant for all postures excepting trunk tilt left and the control. The aftereffect from head tilt was greater than that from the same degree of body tilt, and that in the trunk tilt condition was in the same direction as’ predicted from neck stimulation. In Experiment 2, 30 Ss made AV judgments during tilt in the same seven postures. The E-phenomenon resulted from both head and body tilts, and an effect was found for trunk tilt in the direction predicted from neck stimulation. The results are discussed in terms of the otolith, neck, and trunk receptor systems.