The effect of body and environment-centred coordinates on free-viewing perceptual asymmetries for vertical and horizontal stimuli

Nicholls, MER, Smith, A, Mattingley, JB and Bradshaw, JL (2006) The effect of body and environment-centred coordinates on free-viewing perceptual asymmetries for vertical and horizontal stimuli. Cortex, 42 3: 336-346. doi:10.1016/S0010-9452(08)70360-5


Author Nicholls, MER
Smith, A
Mattingley, JB
Bradshaw, JL
Title The effect of body and environment-centred coordinates on free-viewing perceptual asymmetries for vertical and horizontal stimuli
Journal name Cortex   Check publisher's open access policy
ISSN 0010-9452
Publication date 2006-01-01
Sub-type Article (original research)
DOI 10.1016/S0010-9452(08)70360-5
Volume 42
Issue 3
Start page 336
End page 346
Total pages 11
Place of publication Milano
Publisher Masson Divisione Periodici
Language eng
Abstract Leftward and upward perceptual biases are commonly reported for horizontal and vertical stimuli, respectively. It is unclear, however, whether these biases are based upon body or environment-centred coordinates. Two experiments examined the contribution of these coordinate systems to free-viewing vertical and horizontal perceptual biases. In Experiment 1, normal participants (n = 35) made forced-choice luminance judgments on two mirror-reversed luminance gradients (the 'greyscales' task) presented in vertical and horizontal orientations. Body and environment-based coordinates were dissociated by tilting participants' heads to the left or right. A leftward and upward bias, which was observed in the horizontal and vertical conditions (respectively) when the head was upright, was extinguished when the head was tilted. Results indicated a dual reliance on body and environmental coordinates with some suggestion that the upward bias was more dependent on environmental coordinates. In Experiment 2 the same stimuli were presented as participants (n = 24) adopted an upright or supine pose. Once again, leftward and upward biases were observed in the upright condition. The leftward bias persisted in the supine condition whereas the upward bias was eliminated. Results demonstrate that the leftward bias is based predominantly on body coordinates whereas the upward bias is reliant on environmental/gravitational coordinates. The possibility that the neural basis for the biases lies in the inter-modal centres of the intraparietal region of the right hemisphere is discussed.
Keyword Behavioral Sciences
Neurosciences
neglect
left
right
pseudoneglect
attention
gravity
Lateral Intraparietal Area
Posterior Parietal Cortex
Line Bisection
Reading Habits
Neglect
Pseudoneglect
Representation
Attention
Task
Bias
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
Queensland Brain Institute Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 18 Oct 2007, 00:50:28 EST