Visual psychophysics on the APPLE II: Getting started

Several routines are described for psychophysical procedures on the APPLE II. Method of adjustment and PEST routines are presented within short demonstration programs. Techniques for synchronized presentation of images in tachistoscope and motion displays are given, as well as methods for saving graphics images for later recall.     

Genetic science and pastoral care

Important advances in the field of genetic science have raised new and challenging pastoral issues. This article describes the nature of genetic screening and artificial fertilization and follows each with the relevant pastoral implications.     

Motion and position shifts induced by the double-drift stimulus are unaffected by attentional load

The double-drift stimulus produces a strong shift in apparent motion direction that generates large errors of perceived position. In this study, we tested the effect of attentional load on the perceptual estimates of motion direction and position for double-drift stimuli. In each trial, four objects appeared, one in each quadrant of a large screen, and they moved upward or downward on an angled trajectory. The target object whose direction or position was to be judged was either cued with a small arrow prior to object motion (low attentional load condition) or cued after the objects stopped moving and disappeared (high attentional load condition). In Experiment 1, these objects appeared 10° from the central fixation, and participants reported the perceived direction of the target’s trajectory after the stimulus disappeared by adjusting the direction of an arrow at the center of the response screen. In Experiment 2, the four double-drift objects could appear between 6 ° and 14° from the central fixation, and participants reported the location of the target object after its disappearance by moving the position of a small circle on the response screen. The errors in direction and position judgments showed little effect of the attentional manipulation—similar errors were seen in both experiments whether or not the participant knew which double-drift object would be tested. This suggests that orienting endogenous attention (i.e., by only attending to one object in the precued trials) does not interact with the strength of the motion or position shifts for the double-drift stimulus.     

Visual short-term memory operates more efficiently on boundary features than on surface features

A change detection task was used to estimate the visual short-term memory storage capacity for either the orientation or the size of objects. On each trial, several,objects were briefly presented, followed by a blank interval and then by a second display of objects that either was identical to the first display or had a single object that was different (the object changed either orientation or size, in separate experiments). The task was to indicate whether the two displays were the same or different, and the number of objects remembered was estimated from the percent correct on this task. Storage capacity for a feature was nearly twice as large when that feature was defined by the object boundary, rather than by the surface texture of the object. This dramatic difference in storage capacity suggests that a particular feature (e.g., right tilted or small) is not stored in memory with an invariant abstract code. Instead, there appear to be different codes for the boundary and surface features of objects, and memory operates on boundary features more efficiently than it operates on surface features.     

A unilateral field advantage for detecting repeated elements

Previous studies have shown that letter repetitions are detected more rapidly when presented bilaterally (one letter in each visual field) than when presented unilaterally (both in the same field) when subjects have to report matches independently of case or font (e.g., Aa). This pattern of results is referred to as a bilateral field advantage. Here, we present evidence of an opposite pattern of results for detecting repeated items when they are physically identical. In our repetition detection paradigm, subjects indicated whether there was a repetition of any two of four presented items, one in each quadrant of the visual field. Stimulus classes tested included letters, color, size, orientation, and motion paths. The subjects were significantly faster at detecting unilateral versus bilateral repetitions for four out of the five stimuli classes tested, with a trend in the same direction for the fifth. This unilateral field advantage suggests that low-level processes group physically identical items more efficiently within hemifields than across.     

The spatial resolution of visual attention.

Two tasks were used to evaluate the grain of visual attention, the minimum spacing at which attention can select individual items. First, observers performed a tracking task at many viewing distances. When the display subtended less than 1 degrees in size, tracking was no longer possible even though observers could resolve the items and their motions: The items were visible but could not be individuated one from the other. The limiting size for selection was roughly the same whether tracking one or three targets, suggesting that the resolution limit acts independently of the capacity limit of attention. Second, the closest spacing that still allowed individuation of single items in dense, static displays was examined. This critical spacing was about 50% coarser in the radial direction compared to the tangential direction and was coarser in the upper as opposed to the lower visual field. The results suggest that no more than about 60 items can be arrayed in the central 30 degrees of the visual field while still allowing attentional access to each individually. Our data show that selection has a coarse grain, much coarser than visual resolution. These measures of the resolution of attention are based solely on the selection of location and are not confounded with preattentive feature interactions that may contribute to measures from flanker and crowding tasks. The results suggest that the parietal area is the most likely locus of this selection mechanism and that it acts by pointing to the spatial coordinates (or cortical coordinates) of items of interest rather than by holding a representation of the items themselves.     

PATERNAL AND MATERNAL REFLECTIVE FUNCTIONING IN THE WESTERN AUSTRALIAN PEEL CHILD HEALTH STUDY

While past research on the care of infants has been mostly with mothers, in recent times there has been a renewed attention to the father–infant relationship. This study examined differences between mother and father parental reflective functioning (PRF) or parental mentalizing; that is, the parental capacity to reason about their own and their children's behaviors by taking into consideration intentional mental states. Data were collected from 120 couples with a 1‐year‐old child who were participants in the West Australian Peel Child Health Study. Parental mentalizing was assessed using the Parental Reflective Functioning Questionnaire (PRFQ; Luyten, Mayes, Nijssens, & Fonagy, 2017 ). Results showed that mother and father mentalizing with their children was independent and that mothers scored slightly higher levels of mentalizing than did fathers. Paternal mentalizing was weakly associated with family income and father education, and was more strongly associated with family functioning than with maternal mentalizing. Implications for theorizing on PRF and fatherhood more generally are discussed.     

Pop-out for illusory rather than veridical trajectories with double-drift stimuli

Attention, Perception, & Psychophysics - If a patch of texture drifts in one direction while its internal texture drifts in the orthogonal direction, the perceived direction of this...     

Long-term Evaluation of Genetic Counseling Following False-Positive Newborn Screen for Cystic Fibrosis

This cross-sectional mixed method study was a long-term follow-up evaluation of families who participated in an earlier survey of their understanding of cystic fibrosis (CF) genetics and their infants’ false-positive CF newborn screening (NBS) results. Thirty-seven of the original 138 parents participated in the follow-up telephone survey. Results showed parents who received genetic counseling at the time of their infants’ diagnostic sweat tests had significantly higher long-term retention of genetic knowledge than those without genetic counseling. However, both groups still had misconceptions and lacked accurate information about the actual risk associated with being a CF carrier. Most parents either had already informed (65%) or planned to inform (19%) their children about the child’s carrier status. Mean child age at the time of disclosure was 9.2 years. Situational prompts were the most common reasons for informing their children. Neither parental knowledge, medical literacy, nor parental education predicted whether parents informed their children about their carrier status. False-positive NBS results for CF were not associated with parental perceptions of child vulnerability 11–14 years after the testing. Although the sample from this study was small, these findings underscore the benefits of genetic counseling at the time of the diagnostic sweat test and offer information that can assist parents in talking with their children about the implications of having one CFTR mutation.