Psychophysical evidence for competition between real and illusory contour processing

Luminance defined and illusory contours provide vital information about object borders. However, real and illusory contour cues tend to be used under different contexts and can interfere with one another. Although some cells in visual cortex process both real and illusory contours equivalently, recent studies (Ramsden et al 2001) suggest competitive interactions between real (feedforward) and illusory (feedback) contour processing in primate V1 and V2. To test this hypothesis psychophysically, we designed stimuli in which illusory contours are presented with and without the presence of real line components. If real and illusory contour cues are processed by the same mechanism, then the presence of both cues should enhance the percept. If the illusory percept is degraded by the presence of real lines, then independent real and illusory mechanisms are suggested. The perception of a Kanisza-triangle, presented for 250 msec, was measured under three conditions: 1) virtual contour alone, 2) with a short parallel real line superimposed on the virtual contour or 3) with a short orthogonal real line abutting the virtual contour. The real lines were varied from sub- to supra-threshold contrasts. In a 2AFC paradigm three subjects fixated on a spot in the triangle center and indicated whether the side of the triangle was bent outwards or inwards. We found that real lines degraded the percept of the illusory contour (i.e. increased angular thresholds). Such interference occurred even at subthreshold real line contrasts and, in some subjects, was greater for the parallel than orthogonal real line. Our results support the presence of separate mechanisms for the processing of real and illusory contours and suggest that, under some circumstances, real cues can interfere with the processing of illusory cues. We suggest that such interferences occurs by the feedforward influences of the lines which interfere with the feedback influences prominent during illusory contour processing

Higher Education and behavior analysis in Europe::Creating a unified approach for the training of autism professionals

Training of behaviour analysts for autism services, has improved notably within a European higher education context. However, regional discrepancies associated with economic, health care, social services, and institutional policies magnify the importance of creating appropriate unified training and consumer protection. Although the European Association for Behaviour Analysis (EABA) has endorsed the Behavior Analyst Certification Board’s (BACB) designations, the absence of European and national regulations, recognition, and accreditation remain significant barriers to quality training and implementation. These challenges are  particularly pertinent in light of BACB decision to limit certification to residents in the USA and Canada after 2022. Advances, challenges, and future directions are discussed within the context of higher education in the United Kingdom, the Czech Republic, Greece, Iceland, Italy, Norway, and Sweden. The post-Bologna European agenda for higher education, globalization and opportunities for the training of behaviour analysts within European higher education are outlined

Full field electroretinogram in autism spectrum disorder

Purpose To explore early findings that individuals with autism spectrum disorder (ASD) have reduced scotopic ERG b-wave amplitudes. Methods Dark adapted (DA) ERGs were acquired to a range of flash strengths, (-4.0 to 2.3 log phot cd.s.m-2), including and extending the ISCEV standard, from two subject groups: (ASD) N=11 and (Control) N=15 for DA and N=14 for light adapted (LA) ERGs who were matched for mean age and range. Naka-Rushton curves were fitted to DA b-wave amplitude growth over the first limb (-4.0 to -1.0 log phot cd.s.m-2). The derived parameters (Vmax, Km and n) were compared between groups. Scotopic 15 Hz flicker ERGs (14.93Hz) were recorded to 10 flash strengths presented in ascending order from -3.0 to 0.5 log Td.s to assess the slow and fast rod pathways respectively. LA ERGs were acquired to a range of flash strengths, (-0.5 to 1.0 log phot cd.s.m-2). Photopic 30 Hz, flicker ERGs, oscillatory potentials (OPs) and the responses to prolonged 120 ms ON- OFF stimuli were also recorded. Results For some individuals the DA b-wave amplitudes fell below the control 5th centile of the controls with up to four ASD participants (36%) at the 1.5 log phot cd.s.m-2 flash strength and two (18%) ASD participants at the lower -2 log phot cd.s.m-2 flash strength. However, across the thirteen flash strengths there were no significant group differences for b-wave amplitude’s growth (repeated measures ANOVA p=0.83). Nor were there any significant differences between the groups for the Naka-Rushton parameters (p>0.09). No group differences were observed in the 15Hz scotopic flicker phase or amplitude (p>0.1), DA ERG a- wave amplitude or time to peak (p>26). The DA b-wave time to peak at 0.5 log phot cd.s.m-2 were longer in the ASD group (corrected p=0.04). The single ISCEV LA 0.5 log phot cd.s.m-2 (p0.08) to the single flash stimuli although there was a significant interaction between group and flash strength for the b-wave amplitude (corrected p=0.006). The prolonged 120 ms ON-responses were smaller in the ASD group (corrected p=0.003), but the OFF response amplitude (p>0.6) and ON and OFF times to peaks (p>0.4) were similar between groups. The LA OPs showed an earlier bifurcation of OP2 in the younger ASD participants, however no other differences were apparent in the OPs or 30Hz flicker waveforms. Conclusion Some ASD individuals show subnormal DA ERG b-wave amplitudes. Under LA conditions the b-wave is reduced across the ASD group along with the ON response of the ERG. These exploratory findings, suggest there is altered cone-ON bipolar signalling in ASD

Experiences of Autism Acceptance and Mental Health in Autistic Adults

Mental health difficulties are highly prevalent in individuals on the autism spectrum. The current study examined how experiences and perceptions of autism acceptance could impact on the mental health of autistic adults. 111 adults on the autism spectrum completed an online survey examining their experiences of autism acceptance, along with symptoms of depression, anxiety and stress. Regression analyses showed that autism acceptance from external sources and personal acceptance significantly predicted depression. Acceptance from others also significantly predicted stress but acceptance did not predict anxiety. Further analyses suggested that experiences of “camouflaging” could relate to higher rates of depression. The current study highlights the importance of considering how autism acceptance could contribute to mental health in autism

Public Stigma of Autism Spectrum Disorder at School: Implicit Attitudes Matter

This study examines the public stigma of children with autism spectrum disorder (ASD) by their school-aged peers, focusing on both explicit and implicit attitudes. The twofold aims were to provide a broader picture of public stigma and to explore age-related changes in attitudes. Students completed an explicit measure of the public stigma and an implicit measure of attitudes after watching a video displaying children with ASD vs. typically developing (TD) children. Both measures showed more negative perceptions towards children with ASD compared to TD children. However, while explicit attitudes improved with age, implicit attitudes remained constantly negative. This finding suggests that both explicit and implicit attitudes should be considered when promoting an inclusive climate at school

Space Index: a retrieval-system for building-plots

Increasingly, digital architectural data will become available through information technology. Yet until now, there were no satisfying methods to query this data for architectural purposes. This paper introduces an information retrieval system for parcels that not only allows searching for specific attributes, but also includes properties of shape and context of the building plots. An automatically generated index stores the relevant spatial properties as normalized bitmap images on several layers. When a query is started, only this index has to be queried and not the complete database. The search process can be controlled through a graphical interface that incorporates the useris sketches. The retrieved parcels are presented as a sorted list of vector drawings including their contained buildings. With the simplified access to these case-studies, quality and efficiency of the architectural design process could be increased

Backward masking of illusory contours or their inducers depends on timing

Objects in visual scenes may be only partly visible, rendering the extraction of context-induced illusory contours (ICs) an essential process in object and scene perception. Physiological and psychophysical studies show interaction and overlap between real and illusory processes in the first visual areas, suggesting a feedforward-feedback mechanism with the IC being developped first in V2, but fed back to V1. In such a mechanism real lines would interact early with inducers only, but later predominantly with the IC. We tested this hypothesis in an orientation discrimination task with an oblique abutting line pattern as inducer. The backward mask grating was identical to the inducers, oriented either the same, horizontal, vertical, or opposite oblique. The stimulus was presented for 100 or 130 msec, followed by a 100 msec mask. Orientation discrimination thresholds for the IC under each masking condition were obtained and compared to an unmasked condition. Real lines are masked best by parallel real lines. We thus expected strongest masks to be oriented parallel to the inducers if they interact with the inducers, but parallel to the IC if interfering with the illusory percept. In the hypothesized feedforward-feedback mechanism, we would expect only masking of the IC after completion of the illusory percept. Earlier, however, masks parallel to the inducing stimuli would interfere strongest with perception. At 100 msec presentation time all line patterns were found to mask with varying strength, suggesting either a fragile state in processing, or an overlap between real and illusory processes. We found at 130 msec only masking by lines parallel to the IC, indicating IC-completion. We speculate that even earlier interaction would show solely inducer masking. Our results support the hypothesized mechanism by distinguishing at least two steps of IC processing: mixed processing of inducers and IC at 100 msec, but later processing and neural representation of the IC alone

Color AND motion are what the eye sees best

Watson, Barlow and Robson (1983) argued that the visual stimulus which humans detect best specifies the spatio-temporal structure of the receptive field of the most sensitive visual neurons in the human brain. To investigate 'what the eye sees best' they used various achromatic stimuli (squares, spots and gratings) and found that drifting grating patches were seen best by their observers. A decade later Chaparro, Stromeyer, Huang, Kronauer and Eskew (1993) reexamined this idea using flashed circular spots whose spectral content could be changed. Their best chromatic stimulus was seen 5 - 9 fold better than their best luminance spot and 3-8-fold better than Watson's best stimulus. Here we report experiments with a rectangular stimulus containing two vertically oriented edges of 20 min of arc height. Chromaticity of the edges was chosen from a set of 16 equally detectable colors which covered the whole gamut of color available on a video monitor. For each observer, these colors were adjusted to be equiluminant with respect to the grey background using flicker fusion photometry. Observers fixated a spot in the center of the stimulus such that the two vertical edges were seen at about 1 deg. eccentricity to the left and to the right. After initial fixation of 0.5 sec, the stimulus was presented in one of the 16 colors. After .5 s., at random, one of the vertical edges (left or right) jumped to the left or right and stayed there for another .5 s. Subjects were instructed to report (1) on which side relative to the fixation spot the edge had moved, irrespective of its direction and (2) its direction of motion. For all observers 16 colors were found, for which they correctly reported the direction of motion of the edge, while failing to reliably detect the location of motion irrespective of its direction. Quantitatively, we found that contrast thresholds for identification of the direction of motion were about half of those for detecting the side at which motion was presented or for flashed stimuli of the same chromatic content. As a control we also ran experiments where achromatic edges of various contrasts were presented on the same grey background to the same observers. Now all subjects performed equally well in both tasks. Thus, the high sensitivity for the direction of motion of an edge found in our experiments is due to both the chromatic contents of the stimuli, as well as the spatio-temporal interactions extracting the direction of motion. Comparable results of experiments where the moving edge was presented to the central fovea were described by Kremers, Wachtler, Wehrhahn, Lee Zrenner (1993). We conclude that the stimulus that the eye sees (so far) best, is the direction of a chromatic moving edge