Perceived state of self during motion can differentially modulate numerical magnitude allocation

Abstract

ABSTRACT:Although a direct relationship between numerical-allocation and spatial-attention has been proposed, recent research suggests these processes are not directly coupled. In keeping with this, spatial attention shifts induced either via visual or vestibular motion can modulate numerical allocation in some circumstances but not in others. In addition to shifting spatial attention, visual or vestibular motion-paradigms also (i) elicit compensatory eye-movements which themselves can influence numerical-processing and (ii) alter the perceptual-state of-"self", inducing changes in bodily self-consciousness impacting upon cognitive mechanisms.Thus, the precise mechanism by which motion modulates numerical-allocation remains unknown. We sought to investigate the influence that different perceptual experiences of motion have upon numerical magnitude allocation whilst controlling for both eyemovements and task-related effects. We first used optokinetic visual-motion stimulation (OKS) to elicit the perceptual experience of either "visual world" or "self"-motion during which eye movements were identical. In a second experiment we used a vestibular protocol examining the effects of perceived and subliminal angular rotations in darkness, which also provoked identical eye movements. We observed that during the perceptual experience of "visual-world" motion, rightward OKS biased judgments towards smaller numbers, whereas leftward OKS biased judgments towards larger numbers. During the perceptual experience of "self-motion", judgments were biased towards larger numbers irrespective of the OKS direction. Contrastingly, vestibular motion perception was found not to modulate numerical magnitude allocation, nor was there any differential modulation when comparing "perceived" versus "subliminal" rotations. We provide a novel demonstration that magnitude-allocation can be differentially modulated by the perceptual state of-self during visual-motion.

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“… 20 To further ensure that participants did not develop vection during visual motion viewing, participants planted their feet on the solid ground to reassure them that they were stationary. 29 Eye movements were recorded with horizontal electro-oculography ( figure 1 ).…”

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“…However, we have controlled for any nonspecific cognitive processes affecting numerical task performance by (1) employing the random number generation task18, 19, 20 and not observing any effect and (2) by applying our data to a pre‐existing computational model that supports a hemispheric account of numerical processing10 and observing significant concordance.…”

“…Participants were required to estimate the midpoint (within 6 sec to avoid calculation) of the two numerical magnitudes across the following 20 trials presented in the following temporal sequence (randomized order) (33‐87), (32‐89), (37‐91), (93‐39), (66‐41), (68‐44), (47‐90), (48‐92), (52‐91),(92‐56), (89‐57), (87‐59), (61‐99), (63‐97), (67‐95) (99‐67), (58‐124), (131‐59), (131‐55), and (58‐132) 5, 10, 18. Note, as evident from the trials above, the number presented on the left of the pair varied from being either the larger or the smaller value, to avoid any effects associated with either spatial or temporal biasing.…”

“…Bisection errors were calculated by subtracting the arithmetical midpoint from the participant‐reported midpoint which we converted into percentage bisection errors by dividing the errors with the number interval size. Positive mean % bisection errors denote an overestimation, whereas negative mean % bisection errors denote underestimation from the actual midpoint 5, 10, 18…”

“…The rationale for selecting this task is that it recruits distinct neural mechanisms to those associated with number‐pair bisection but critically is dependent upon numerical cognition and similarly invokes general cognitive functions akin to those during number‐pair bisection 18, 19, 20…”