Nonlinearity in color space measured by apparent motion

We used an apparent motion technique to examine the intensity coding along the three cardinal axes of color space: achromatic (L + M + S), L-M cone, and S cone axes. Two horizontal bars of different colors were alternated to produce a vertical displacement. The color of the background was a mixture varied between the colors of the two bars. When the background color was close to either of the test colors, only the bar that was more salient appeared to jump. Observers adjusted the color of the background until they saw either the two bars moved equally frequently or both bars moved at once. If the color difference in a linear cone excitation space controls this apparent motion, the setting should be midway between the two colors. All of the three cardinal axes showed some deviation from linear behavior. The nonlinearity was less extreme than a logarithmic function for both the achromatic and S cone axes and could be attributed to a small compressive nonlinearity, possibly at the level of cone responses. However, the L-M stimuli showed a more extreme departure from linearity, which suggested a nonlinearity at an opponent site. A test of perceived contrast judgments did not show this nonlinearity for L-M axis, suggesting that it is specific to the L-M contribution to apparent motion.     

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.     

Priming attachment security improves attitudes towards a range of therapies

We sought to understand how attachment orientation influenced attitudes towards different types of psychological therapies. In two studies, we (1) examined attachment orientation as a predictor of attitudes towards different therapies and (2) tested whether attachment security priming could improve attitudes. Study 1 (n = 339) found associations between attachment orientation and attitudes towards, and likelihood of using different therapies. Positive and negative attitudes about different therapies mediated the relationship between attachment avoidance and likelihood of use. Study 2 (n = 412) showed that primed security (vs. neutral prime) improved attitudes towards relational, non‐relational and distanced‐relational therapies for those with a fearful‐avoidant attachment orientation. For relational and distanced‐relational therapies, the mechanism of this effect was increased cognitive openness. Attachment orientation is a determinant of therapy attitudes and anticipated help‐seeking behaviour. Priming security may promote open‐minded decision‐making about some therapies. Findings are discussed with relevance to attachment theory, research and clinical practice.     

A moving display which opposes short-range and long-range signals

A novel display is described which stimulates both the long-range and the short-range motion detecting processes simultaneously, but with opposing directions of movement. The direction in which the stimulus appears to move depends on retinal eccentricity and element size, but adaptation to the display always produces a motion aftereffect (MAE) direction opposite to the direction of the short-range component. The display may offer insights into the properties of the two-process motion detecting system.     

The role of transparency in perceptual grouping and pattern recognition.

The shortest stimulus exposure time for which transparency can be seen was examined. In the first experiment, overlapping digits were presented for 120 ms and the luminance in the overlapping regions was varied. Subjects reported, in separate blocks of trials, either the apparent transparency of the digits or the identity of the digits. When the luminance was set so that one set of digits appeared to be seen through the other, recognition of the digits was high. When the luminance in the overlapping regions did not produce impressions of transparency, digit recognition was low. In the second experiment, digit identification at several stimulus durations was compared between stimuli that had luminance that was valid for transparency and stimuli that had invalid luminance. Performance was found to be higher in the valid luminance condition than in the invalid condition after as little as 60 ms exposure duration. This result suggests that the impression of transparency requires only relatively short exposure durations.     

Vision with equiluminant colour contrast: 2. A large-scale technique and observations.

A simple technique is described for producing large-scale, tritanopic displays. The technique reproduces the various phenomena of vision with equiluminous-colour contrast that have previously been reported with red/green stimuli. It is, however, much less demanding technically, robust against artifacts, and can be used on large-scale scenes. One advantage of the technique is that a piece of blue filter can be used individually by each observer to compare quickly tritanopic and luminance conditions.     

Size and position invariance in the visual system

The encoding of simple features such as lines and angles leads naturally to size and position invariance when these features are analyzed symbolically in terms of structure and connectedness. No such analysis is possible for a spatial frequency encoding, however, as all a priori indications of pattern unity are lost. An additional transformation of spatial frequency information is therefore demonstrated that automatically derives a size invariant representation of form. The feasibility of the transform scheme in the visual system is outlined with a hypothetical processing sequence. It is found that the organization of cells in the striate cortex shows a marked similarity to an intermediate stage of the proposed sequence.