Luminance and Colour Flicker Fusion in High and Low Autistic Traits
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1
Swinburne University, Australia
Background
Neurophysiological mechanisms underlying altered visual perception in autistic tendencies are currently poorly defined. Differences in magnocellular processing have been implicated in the impaired motion sensitivity and different global/local integration style associated with autistic tendency.
Method
Flicker fusion tasks were utilised to examine temporal processing differences in a non-clinical population displaying high and low autistic tendencies as measured by Baron-Cohen’s Autism spectrum Quotient (AQ). Isoluminant red/green flicker was used to measure temporal processing capacity of the parvocellular system (2AFC) and similarly, isoluminant blue/yellow flicker used to measure koniocellular pathway function (2AFC). The temporal processing capacity of the magnocellular system was measured as a function of contrast with critical luminance flicker thresholds measured at 5 different temporal contrast levels (5%, 25%, 50%, 75%, 100%) using a 4AFC method. Calibrated LEDs were viewed through 5mm diameter optic fibers, amplitude, DC level and frequencies were modulated using VPixx software via a DataPIXX interface system.
Results
Data obtained supports previous findings showing critical flicker thresholds improve with increasing contrast levels, from 32Hz at 5% contrast to 47Hz at 100% temporal contrast (correlation R2 =.47, significant to .001). Blue/yellow flicker had a marginally higher mean colour fusion rate (18.3Hz) than the red/green fusion task (16.8 Hz). Between groups analysis shows for all flicker tasks that individuals with high AQ have lower luminance flicker fusion rates then those with low AQ.
Discussion
The finding that those with higher AQ scores are less able to perceive flicker – especially for luminance modulation at the limits of high frequency, is suggestive of impaired magnocellular function, despite previous reports of insignificant differences in flicker contrast sensitivity.
Keywords:
temporal processing,
autistic traits,
Flicker Fusion,
Magnocellular,
Parvocellular
Conference:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013.
Presentation Type:
Poster
Topic:
Sensation and Perception
Citation:
Brown
A,
Crewther
DP,
Thompson
J,
Karvelas
G,
Guarnaccia
C,
Hartwell
C and
Peck
C
(2013). Luminance and Colour Flicker Fusion in High and Low Autistic Traits.
Conference Abstract:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference.
doi: 10.3389/conf.fnhum.2013.212.00091
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Received:
25 Sep 2013;
Published Online:
25 Nov 2013.
*
Correspondence:
Ms. Alyse Brown, Swinburne University, Melbourne, Australia, amailboxx@hotmail.com