Attentional Processing in Bistable Perception is Influenced by Genetic Effects Associated with Sinistrality

Attentional Processing in Bistable Perception is Influenced by Genetic Effects Associated with Sinistrality. Roeland Hancock (rhancock@email.arizona.edu) Department of Psychology, 1503 E. University Blvd. Tucson, AZ 85721 USA Abstract and Necker cube displays (Shannon, Patrick, Jiang, Bernat, & He, 2011). Several factors, including the visual properties of the stimuli (e.g. intensity (Levelt, 1967)), eye movements and attention, have been proposed to affect perceptual rever- sals. Binocular rivalry displays and ambiguous figures such as the Necker cube elicit a perceptual reversal effect mediated by attentional and perceptual processes. Perceptual dominance times are highly variable between individuals and may be par- tially influenced by genetic factors. This study examined the role of putative genetic effects associated with familial sinis- trality, derived from a novel pedigree-based genetic model. In a continuous Necker viewing task, dominance times were sig- nificantly correlated (R 2 = .36) with a multifactorial estimate of genetic effects associated with non right-handedness. No association with genetic estimates was found in an intermittent viewing condition. These results suggest that genetic factors associated with functional asymmetries may also affect noise- based perceptual alternation, but not short term visual memory. Eye movements are related to perceptual reversals, but it is not clear that eye movements directly cause reversals. Fix- ating on one face of the Necker cube biases perception, but does not eliminate perceptual alternation, suggesting that re- versals are not merely the result of scanning different areas of the visual field (Toppino, 2003). Scotto, Oliva, and Tuc- cio (1990) showed Necker cube images that were partially corrected for eye-movements which resulted in an increased reversal rate over normal viewing conditions, further sug- gesting that bistable perception is not merely a product of scanning eye movements across the visual field. van Dam and van Ee (2005) examined the relation between percep- tual reversals and eye movements and found no correlation between reported reversals and involuntary micro-saccades, however saccades and eye blinks were suppressed prior to button presses. This suppression occurred both when sub- jects reported perceptual flips and experimentally controlled stimulus flips. The number of blinks and saccades did not de- crease prior to random button presses that were unrelated to the stimulus. Thus, bistable perception appears to be related to a cognitive process that then directs visual attention, rather than the direct result of visual field changes. Keywords: Bistable Perception; Attention; Individual Differ- ences; Familial Sinistrality Introduction Functional cerebral lateralization has been proposed to arise from a combination of constraints on interhemispheric con- nectivity (Ringo, Doty, Demeter, & Simard, 1994) and the properties, such as excitability, of neural assemblies within each hemisphere (Levitan & Reggia, 2000). Cerebral later- alization, particularly for language, is often associated with individual hand preference as well as the handedness of close relatives (Tzourio-Mazoyer et al., 2010), suggesting a genetic contribution to functional asymmetry. Genetic effects associ- ated with familial handedness may in turn be linked to sub- tle neurobiological differences, including the distribution of neurotransmitters involved in regulating neural excitability, noise or interhemispheric connectivity. We adopt a simple behavioral paradigm, the Necker cube viewing task, that may be sensitive to these factors at multiple time scales to iden- tify possible associations between neural function and famil- ial handedness. A variety of ambiguous visual displays can induce bistable (or multistable) perception in observers, a state in which the subjective interpretation of the display alternates between perspectives. This can be induced through ambiguous fig- ures (e.g. the Necker cube and Rubin’s face/vase illusion), ambiguous motion or binocular rivalry displays in which dif- ferent images are shown to each eye. Binocular rivalry dis- plays allow more control over stimulus presentation and are more widely studied than ambiguous displays, but similar processes are assumed to drive alternation in both types of displays. Dominance times–the duration for which a particu- lar interpretation is perceived–are highly variable between in- dividuals (Aafjes, Hueting, & Visser, 1966) and may be par- tially influenced by genetic factors in both binocular rivalry The present study investigates individual variability in Necker cube dominance times as a function of putative ge- netic effects associated with hand preference. Handedness and familial sinistrality are known to affect lateralization of other brain functions, notably language (Tzourio-Mazoyer et al., 2010). Familial sinistrality has also been found to in- fluence spatial processing (e.g. Mckeever (1986)) and rest- ing brain states (Hancock, 2012), but has not been widely studied with respect to the cognitive processes involved in bistable perception. Although Necker cube viewing is typ- ically not a lateralized task, fMRI and EEG studies suggest that the reversal phenomenon is right-lateralized, at least ini- tially (Pitts, Mart´inez, Stalmaster, Nerger, & Hillyard, 2009; Britz & Pitts, 2011) and dominance time is associated with grey matter volume in the right, but not left, superior pari- etal lobe (Kleinschmidt, Sterzer, & Rees, 2012). Unilateral transcranial magnetic stimulation and caloric stimulation can disrupt binocular rivalry and Necker cube reversals (Miller et al., 2000), supporting bilateral contributions to bistable per- ception. While interhemispheric transfer across the corpus