Effects of peripheral eccentricity and head orientation on gaze discrimination

Visual search tasks support a special role for direct gaze in human cognition, while classic gaze judgement tasks suggest the congruency between head orientation and gaze direction plays a central role in gaze perception. Moreover, whether gaze direction can be accurately discriminated in the periphery using covert attention is unknown. In the present study, individual faces in frontal and in deviated head orientations with a direct or an averted gaze were flashed for 150 ms across the visual field; participants focused on a centred fixation while judging the gaze direction. Gaze discrimination speed and accuracy varied with head orientation and eccentricity. The limit of accurate gaze discrimination was less than ±6° eccentricity. Response times suggested a processing facilitation for direct gaze in fovea, irrespective of head orientation, however, by ±3° eccentricity, head orientation started biasing gaze judgements, and this bias increased with eccentricity. Results also suggested a special processing of frontal heads with direct gaze in central vision, rather than a general congruency effect between eye and head cues. Thus, while both head and eye cues contribute to gaze discrimination, their role differs with eccentricity.     

Children's strategic compensation for size underconstancy: Dependence on distance and relation to reasoning ability

When asked to judge the size of a distant object, older children are more likely than younger ones to report deliberately inflating their judgements to compensate for size underconstancy (Granrud, in press). The current investigation examined whether use of this strategy depends on object distance and whether it is related to individual differences in reasoning, knowledge about size perception, or cognitive style. In two studies, children in Grades 1–3 estimated the size of a distant (61 m away) and near (6.1 m away) disc. In each, half of the children reported inflating their judgement of the distant disc to compensate for a tendency to underestimate its size, but only a few reported using this strategy for the near disc. Self-reported strategy users tended to either judge the distant disc accurately or to overestimate its size, whereas the other children tended to underestimate its size. Strategy reporters obtained higher scores on a test of verbal reasoning, but did not differ from the other children in reflectivity-impulsivity. In Study 1, strategy reporters also showed a better understanding of how distance affects the apparent size of objects in photographs. This understanding was strongly related to verbal reasoning ability. In Study 2, visuospatial reasoning ability was also found to predict who would report strategy use, and this predictive relation was independent of verbal reasoning ability.     

The culture of yoga retreats,active followers and peripheral associates of new religious movements: wellness enterprises promoting well-being

ABSTRACT

This paper examines the wellness effects of yoga retreats on Indian guru-led new religious movements’ (NRMs) fellowship. The two-year repeated-measures study included 3658 active followers and 3658 peripheral associates as the comparison group. Two measures assessed wellness: the Flourishing Scale (FS) and the Comprehensive Inventory of Thriving (CIT). Phase 1 scores of both groups were not significantly different. Active followers who attended yoga retreats scored higher at phase 2 on the FS and the CIT than the peripheral associates. Within the active followers’ cohort, women, upper class, Hindus and never married/widowed had higher phase 2 FS and CIT scores. Active followers who attended retreats for meditation and reflection, practiced yoga, prayer and personal study during retreats, and regularly maintained the spiritual routine after retreats, acquired several psychological resources and strengths. Hence, active and serious followers of the Indian guru-led NRMs psychologically gain as a result of experiencing yoga retreats.     

Roles of Visual Information for Control of Reaching Movements in Children

Poststroke hemiparetic individuals (n = 9) and a control group (n = 9) completed a frequency-scaled circle-drawing task in unimanual and bimanual conditions. Measures of intralimb spatial and temporal task accuracy and interlimb coordination parameters were analyzed. Significant reductions in task performance were seen in both limbs of the patients and controls with the introduction of bimanual movement. Spatial performance parameters suggested that the 2 groups focused on different hands during bimanual conditions. In the controls, interlimb coordination variables indicated predictable hand dominance effects, whereas in the patient group, dominance was influenced by the side of impairment and prior handedness of the individual. Therefore, in this particular bimanual task, performance improvements in the hemiplegic side could not be elicited. Intrinsic coupling asymmetries between the hands can be altered by unilateral motor deficits.     

Evidence Supporting the Importance of Peripheral Visual Information for the Directional Control of Aiming Movement

The focus of the present study was on determining whether the high level of directional accuracy found in aiming studies in which the subjects can see their hand in the visual periphery supports the existence of a kinetic visual channel or, rather, the advantage of binocular over monocular vision for movement directional control. The limits of this kinetic visual channel were also explored. The results of the 1st experiment indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy. Further, no differences in aiming accuracy were noted between monocular and binocular vision. These results supported the existence of a visual kinetic channel. In the 2nd experiment, whether this kinetic visual channel would operate with movements slower (55°/s) than those usually used in studies that had proved its existence (over 110°/s) was determined. The results indicated that this visual kinetic channel was operative even at relatively slow movement velocities. Central vision of the hand seemed to be used for on-line directional control of relatively slow movements.     

Paleolithic Art and Cognition

In this article, I have explored some of the possible relationships between the first appearance of representational art in human history and the early development of human cognition. I argue that most Upper Paleolithic depictions directly represent generalized mental images of their animal subjects rather than percepts or recollected scenes from life and that these images, in turn, are representations of concepts at the basic level of categorization. A common feature of Paleolithic art forms is the salience of parts, and the treatment of parts indicates analytic and synthetic (recombinative) abilities. There are some indications of superordinate categorization. An expansion of conceptual thinking seems to be implied as well as the beginnings of operational thought. The presence and practice of depiction may have had the effect of bringing concepts into consciousness and thus inducing reflection in at least a partially abstract mode.     

Visual Consciousness and The Phenomenology of Perception

Ideally, psychological and phenomenological studies of visual experience should be mutually informative. In that spirit, this article outlines parts of Maurice Merleau‐Ponty's phenomenological view of visual experience as a kind of independently active opaque bodily synthesis, and uses those views to (a) help ground and extend Alva Noë's rejection of the “snapshot” theory of visual experience in favor of a more enactive view of visual content, (b) critique a failing of Noë's account, and (c) show how the assumptions underlying more internalist and Cartesian views of visual experience can illegitimately creep in even when they are being carefully criticized.     

The Visuomotor System Resists the Horizontal-Vertical Illusion

The effect of the horizontal-vertical illusion on the visual and visuomotor systems was investigated. Participants (N = 8) viewed horizontal and vertical lines in an inverted-T stimulus and judged whether the two line segments were the same or different lengths. Participants also reached out and grasped either the vertical or the horizontal line segment of the stimulus. Perceptually, participants succumbed to the illusion; that is, they judged Ts of equal horizontal and vertical line lengths to be different and Ts of unequal line lengths to be the same. When reaching toward the same stimuli, however, the size of their grip aperture was scaled appropriately for the various line lengths. Thus, whereas the perceptual system succumbed to the illusion, the visuomotor system did not. Those results support a model proposed by M. A. Goodale and A. D. Milner (1992), who posited separate cortical pathways for visual perception and visually guided action.     

Stimulus Generalization and the Peak Shift with Movement Stimuli

Stimulus generalization is suggested as an alternative method for examination of the “novelty? problem in motor learning. These experiments demonstrated that stimulus generalization occurs using simple movements as stimuli. The phenomenon of the “peak shift? in post-discrimination generalization gradients was also examined. The first experiment demonstrated that a peak shift occurred using linear movements as stimuli and that the magnitude of the peak shift increased as the difference between the training stimuli decreased. The second experiment showed similar results when the stimuli consisted of a range of movements rather than a single movement length. The final experiment provided evidence that perception of movement length is influenced by the magnitude of an immediately preceding movement. The relevance of these studies to current motor-learning theory is discussed.     

The Dynamics of Visual Reweighting in Healthy and Fall-Prone Older Adults

Multisensory reweighting (MSR) is an adaptive process that prioritizes the visual, vestibular, and somatosensory inputs to provide the most reliable information for postural stability when environmental conditions change. This process is thought to degrade with increasing age and to be particularly deficient in fall-prone versus healthy older adults. In the present study, the authors investigate the dynamics of sensory reweighting, which is not well-understood at any age. Postural sway of young, healthy, and fall-prone older adults was measured in response to large changes in the visual motion stimulus amplitude within a trial. Absolute levels of gain, and the rate of adaptive gain change were examined when visual stimulus amplitude changed from high to low and from low to high. Compared with young adults, gains in both older adult groups were higher when the stimulus amplitude was high. Gains in the fall-prone elderly were higher than both other groups when the stimulus amplitude was low. Both older groups demonstrated slowed sensory reweighting over prolonged time periods when the stimulus amplitude was high. The combination of higher vision gains and slower down weighting in older adults suggest deficits that may contribute to postural instability.