Autism is a behaviourally defined disorder. The impairments in social communication and repetitive behaviours are individually non-specific. The disorder has indistinct boundaries both with other psychiatric disorders and with normal personality types. At the cognitive level, groups of people with autistic disorder can be differentiated from people without the disorder by their ability to reason about beliefs and knowledge (Theory of Mind) and by tests of visual disembedding (central coherence). This study examined whether young people with some of the behavioural features of autism but not necessarily a diagnosis, would show this distinctive cognitive profile. In a sample of 60 young people with additional learning support needs, we found that those with high levels of autistic traits (n=40) showed the same cognitive profile as has been found in people diagnosed with autistic disorder. This supports the view that autism is an extreme on a continuum of cognitive traits. Given the highly heritable nature of autism, we hypothesised that the parents of the young people with autistic traits will also display these cognitive features. The results indicated that there was no difference between the groups of parents on an advanced test of social cognition. Parents of people with high autistic traits were more resistant to one of the visual illusions and saw fewer reversals of an ambiguous figure when IQ was statistically controlled. These results in a sample with a low genetic load suggest ambiguous figures will be important in delineating the broader cognitive phenotype of autism.

The dissertation examines the problem of temporally uneven information processing in the nervous system. We chose binocular rivalry and ambiguous figure perception for our research, as these phenomena are pronounced examples of cyclical processes in perception. Binocular rivalry and ambiguous figure perception are cases in perception, when the subjective perception every few seconds vacillates between alternative interpretations, while the physical stimulation remains constant. Our research examines the relationship between these perception alterations and millisecond-order cycles of information processing in the nervous system. We created special equipment to present visual stimuli intermittently (flickering) and examined, whether the flickering rate of the stimuli influences the temporal characteristics (mean dominance duration) of binocular rivalry and ambiguous figure perception. The results confirmed the relationship, but also highlighted the temporal instability of binocular rivalry dominance durations. / Disertacijoje nagrinėjama informacijos apdorojimo procesų nervų sistemoje laikinio netolygumo problema. Tyrimui pasirinkti akių konkurencijos ir dviprasmių figūrų suvokimo reiškiniai, ryškiai atspindintys suvokimo procesų cikliškumą. Akių konkurencija ir dviprasmių figūrų suvokimas yra reiškiniai, kuomet fiziniam stimului nesikeičiant, subjektyvus suvokimas kas kelias sekundes kaitaliojasi tarp alternatyvių interpretacijų. Tyrime nagrinėjamas šių sekundinių suvokimo ciklų ryšys su milisekundžių eilės informacijos apdorojimo ciklais. Sukurta speciali aparatūra, kuria stimulai į akis buvo pateikti mirksintys nustatytu dažniu, ir tikrinta, ar stimulų mirksėjimo dažnis lemia akių konkurencijos ir dviprasmių figūrų suvokimo laikines savybes (vidutinę dominavimo trukmę). Rezultatai patvirtino šį ryšį, tačiau taip pat nustatyta, kad akių konkurencijos vidutinei dominavimo trukmei yra būdingas laikinis nestabilumas – dominavimo trukmė gana didele amplitude kinta kelių minučių, valandos ir kelių parų eigoje.

Disertacijoje nagrinėjama informacijos apdorojimo procesų nervų sistemoje laikinio netolygumo problema. Tyrimui pasirinkti akių konkurencijos ir dviprasmių figūrų suvokimo reiškiniai, ryškiai atspindintys suvokimo procesų cikliškumą. Akių konkurencija ir dviprasmių figūrų suvokimas yra reiškiniai, kuomet fiziniam stimului nesikeičiant, subjektyvus suvokimas kas kelias sekundes kaitaliojasi tarp alternatyvių interpretacijų. Tyrime nagrinėjamas šių sekundinių suvokimo ciklų ryšys su milisekundžių eilės informacijos apdorojimo ciklais. Sukurta speciali aparatūra, kuria stimulai į akis buvo pateikti mirksintys nustatytu dažniu, ir tikrinta, ar stimulų mirksėjimo dažnis lemia akių konkurencijos ir dviprasmių figūrų suvokimo laikines savybes (vidutinę dominavimo trukmę). Rezultatai patvirtino šį ryšį, tačiau taip pat nustatyta, kad akių konkurencijos vidutinei dominavimo trukmei yra būdingas laikinis nestabilumas – dominavimo trukmė gana didele amplitude kinta kelių minučių, valandos ir kelių parų eigoje. / The dissertation examines the problem of temporally uneven information processing in the nervous system. We chose binocular rivalry and ambiguous figure perception for our research, as these phenomena are pronounced examples of cyclical processes in perception. Binocular rivalry and ambiguous figure perception are cases in perception, when the subjective perception every few seconds vacillates between alternative interpretations, while the physical stimulation remains constant. Our research examines the relationship between these perception alterations and millisecond-order cycles of information processing in the nervous system. We created special equipment to present visual stimuli intermittently (flickering) and examined, whether the flickering rate of the stimuli influences the temporal characteristics (mean dominance duration) of binocular rivalry and ambiguous figure perception. The results confirmed the relationship, but also highlighted the temporal instability of binocular rivalry dominance durations.

When viewing ambiguous figures, individuals can exert selective attentional control over their perceptual reversibility behaviour (e.g., Strüber & Stadler, 1999). In the current study, we replicated this finding but we also found that ambiguous figures containing faces are processed quite differently from those containing objects. Furthermore, inverting an ambiguous figure containing faces (i.e., Rubin’s vase-face) resulted in an “inversion effect”. These findings highlight the importance of considering how we attend to faces in addition to how we perceive and process faces. Describing the perceptual reversal patterns of individuals in the general population allowed us to draw comparisons to behaviours exhibited by individuals with Asperger Syndrome (AS). The group data suggested that these individuals were less affected by figure type or stimulus inversion. Examination of individual scores, moreover, revealed that the majority of participants with AS showed an atypical reversal pattern, particularly with ambiguous figures containing faces, and an atypical inversion effect. Together, our results show that ambiguous figures can be a very valuable tool for examining face processing mechanisms in the general population and other distinct groups of individuals, particularly those diagnosed with AS. / October 2008

Four studies including ten experiments adresses interrelations between some major and classical issues in visual perception: 3-D perception, colour constancy, colour perception and colour vision deficiencies. The main experimental paradigm to investigate the issues is within that of simulated shape from shading. 3-D impressions are induced by projecting space-modulated illuminations onto flat surfaces (displays), varying the colours and layout of the displays and the colour and modulation of the illumination. Study I includes four experiments investigating three types of space- modulated illumination. All experiments confirmed earlier findings that chromatic colour and complex display layout with reflectance edges crossed by illumination edges enhances shape from shading. In Study II the impressions of shape from shading and real 3-D objects were compared between persons with deutan colour vision deficiencies and normals. As predicted, the deutans show fewer and less distinct 3-D impressions in situations with their specific "problem colours" red and green. They also show a generally lower tendency for 3-D impressions, interpreted as a generally weaker colour constancy. Study III presents the AMBEGUJAS phenomenon; a novel twofold ambiguous shape from shading situation, continuously alternating between two different 3-D impressions coupled with different colour attributions. One solution is of an object with two clear surface colours, the other one of an object with greyish (desaturated) colours in coloured illumination which means classical colour constancy. The phenomenon illustrates the visual processes of separating reflectance and illumination characteristics and may provide a useful experimental setting to study colour constancy. In Study IV the AMBEGUJAS phenomenon is found to be robust as to chromaticness and different luminance contrasts for both normals and deutans. However, the deutans show slower shifts between percepts and a less pronounced desaturation of colour, which indicates a weaker colour constancy. The studies add evidence to the contribution of colour to 3-D shape perception, validated in a novel way by the results on "colour-blinds". The AMBEGUJAS phenomenon provides further support that the factors affecting shape from shading and the deutans different impressions are to be understood with reference to colour constancy. The deutans different impressions compared to normals are remarkable per se, but probably with very limited implications to everyday life. / <p>Diss. (sammanfattning) Umeå : Umeå university, 1996, härtill 4 uppsatser</p> / digitalisering@umu

When viewing ambiguous figures, individuals can exert selective attentional control over their perceptual reversibility behaviour (e.g., Strüber & Stadler, 1999). In the current study, we replicated this finding but we also found that ambiguous figures containing faces are processed quite differently from those containing objects. Furthermore, inverting an ambiguous figure containing faces (i.e., Rubin’s vase-face) resulted in an “inversion effect”. These findings highlight the importance of considering how we attend to faces in addition to how we perceive and process faces. Describing the perceptual reversal patterns of individuals in the general population allowed us to draw comparisons to behaviours exhibited by individuals with Asperger Syndrome (AS). The group data suggested that these individuals were less affected by figure type or stimulus inversion. Examination of individual scores, moreover, revealed that the majority of participants with AS showed an atypical reversal pattern, particularly with ambiguous figures containing faces, and an atypical inversion effect. Together, our results show that ambiguous figures can be a very valuable tool for examining face processing mechanisms in the general population and other distinct groups of individuals, particularly those diagnosed with AS.

When viewing ambiguous figures, individuals can exert selective attentional control over their perceptual reversibility behaviour (e.g., Strüber & Stadler, 1999). In the current study, we replicated this finding but we also found that ambiguous figures containing faces are processed quite differently from those containing objects. Furthermore, inverting an ambiguous figure containing faces (i.e., Rubin’s vase-face) resulted in an “inversion effect”. These findings highlight the importance of considering how we attend to faces in addition to how we perceive and process faces. Describing the perceptual reversal patterns of individuals in the general population allowed us to draw comparisons to behaviours exhibited by individuals with Asperger Syndrome (AS). The group data suggested that these individuals were less affected by figure type or stimulus inversion. Examination of individual scores, moreover, revealed that the majority of participants with AS showed an atypical reversal pattern, particularly with ambiguous figures containing faces, and an atypical inversion effect. Together, our results show that ambiguous figures can be a very valuable tool for examining face processing mechanisms in the general population and other distinct groups of individuals, particularly those diagnosed with AS.

Background Research has shown that people need to be pre-informed about the ambiguity in order to perceive both interpretations (reverse) of an ambiguous figure. Children younger than 4 years mostly do not experience reversal even when informed. This suggests that the processes involved in reversal develop at this age. Aim The aim of the studies reported here was to disentangle the cognitive processes (metarepresentation, executive function, mental imagery) and the role of eye-movements involved in reversal. Method Four studies (7 experiments), each involving around sixty 3-, 4- and 5-year-old children, using multiple tasks, were conducted. The primary tasks used were the Ambiguous Figures Production and Reversal tasks. The secondary tasks used were metacognitive, executive function and mental imagery tasks. New tasks were also implemented in order to assess reversal abilities. Results Between the ages of 3 and 4 children develop the basic conceptual understanding for reversal (Study 1), that an ambiguous figure can have two interpretations. This is associated with the understanding of false belief, synonymy and homonymy. Between the ages of 4 and 5 children develop inhibitory (Study 3) and image generation abilities (Study 4). These are key cognitive processes necessary for reversal. Contrary to previous research, when task demands were changed (Reversal Task Revised) children’s reversal is at ceiling by the age of 5 (Studies 3 and 4). Eye-tracking data suggests that appropriate eye-movements, focusing on particular parts of the ambiguous figure, are not a primary causal factor in the development of reversal abilities (Study 4). Conclusion The ability to reverse develops in two stages. During stage 1 (between 3 and 4 years) children develop the necessary conceptual understanding that an ambiguous figure can have two interpretations (top-down knowledge). During stage 2 (between 4 and 5 years) children develop the necessary cognitive processes for reversal to occur (inhibition and image generation).