Recent research has suggested that impairment in autism may lie in the ability of the gaze processing system to adapt to recent context. The present study investigated whether variation in autistic-like traits is related to the size of gaze aftereffects and whether reduced adaptation aftereffect also affects lower-level perceptual stimuli. Participants included 344 UWA psychology students. An eye-gaze and tilt adaptation task was used to measure participant aftereffect size. The
Autism-Spectrum Quotient (AQ) was used to determine the level of autistic traits. The difference between scores on baseline and adaptation phases resulted in significant aftereffect sizes for both gaze and tilt. However, no correlation was found between AQ, tilt or gaze aftereffect sizes. This finding suggests that the level of autistic traits had no effect on participant’s ability to adapt to prolonged exposure to gaze or luminance gratings.
Gaze and Tilt Aftereffects For Self-Rated Autistic Traits
Gaze is a crucial element of social interaction. During typical development infants as young as five months are sensitive to adult gaze changes as small as 5° (i.e. from ears to the eyes) (Symons
1998). Sensitivity to gaze direction is considered a fundamental aspect in developing an ability to infer mental states of others (Baron-Cohen 1997). Recent research has centred on understanding how gaze direction is perceived and interpreted in autism. Autism is a hereditary neural development disorder that has significant effects on social interaction, including verbal and nonverbal communication (Association 2000). Autistic individuals engage less frequently in direct eye to eye contact (Sigman 1986), joint attention (Charman 1997) and gaze following (Leekam 1998).
Attention cueing studies have reported that both age matched controls and autistic children shift their attention in a similar way (Nation 2008), suggesting that the non-verbal deficits are not the result of a more general impairment in visual attention orienting.
Studies using sensitive gaze categorisation tasks suggest that sensitivity to subtle deviations in gaze direction may play an important role in explain these deficits. A study by (Campbell 2006) showed when making judgements about fine grained gaze direction (0°, 2°, 4°, and 8° left/right), autistic school age children performed worse than typical children (Campbell 2006). Similarly, when detecting the target of another’s gaze when targets were separated by 5° and 10°, an impairment was seen for school age children, but not for adolescents, with autism (Webster 2008).
These results suggest impairment for the mechanisms underlying gaze discrimination, specifically relating to subtle deviations in gaze direction.
(Pellicano 2013) suggested that the cause of impairment in autism may lie in the ability of the gaze processing system to adapt to recent context.
Adaptation is a process that occurs in the sensory systems, characterised by continuous recalibration of neural sensitivity to adjust to recent context. Adaptation affects moment to moment sensory processing (Kohn 2007) and could be responsible for improving perceptual discrimination (Krekelberg 2006). Adaptation occurs for relatively simple stimulus features, such as orientation (Gibson 1937) and colour (Webster 1991). For example, (Gibson 1937) demonstrated that extended exposure to an oriented pattern grating (adaptor) affects the perceived orientation of a successive pattern gratings, known as the tilt aftereffect. For adapting line orientations between 0° and 50° , subsequent vertical test gratings are judged by observers as opposite in orientation to the adaptor in orientation (Gibson 1937). For individuals with autism it is common for atypical processing of these low-level perceptual features (Happé 1999). Importantly individuals with autism have shown superiority for identifying the orientation of these simple luminance gratings
Adaptation can also