Head turns bias the brain's internal random generator

Loetscher, Tobias; Schwarz, Urs; Schubiger, Michèle N.; Brugger, Peter

doi:10.1016/j.cub.2007.11.015

Cited by 161 publications

(187 citation statements)

References 15 publications

(14 reference statements)

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“…Well aware that these correlations not necessarily imply causation, we nevertheless speculated about a spatial component intrinsic to RNG (Loetscher & Brugger, 2007b). In a follow-up study we found further evidence for this assumption (Loetscher, Schwarz, Schubiger, & Brugger, 2008) when we demonstrated that turning one's head to the left side of space enhanced one's preference for small digits when mentally generating numbers "at random". Thus, a mechanism known to allocate spatial attention in the outside world (head turning) seemed to influence random number choices systematically.…”

Section: )mentioning

confidence: 51%

Random number generation in neglect patients reveals enhanced response stereotypy, but no neglect in number space

Loetscher

Brugger

2009

Neuropsychologia

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Based on interactions between number and space apparent from healthy subjects' randomization attempts we expected random number generation (RNG) to be sensitive for the monitoring of unilateral spatial deficits. Specifically, we predicted patients with left-sided hemineglect to evidence "neglect in number space", i.e. to produce a deficiency in the generation of small, "left-sided" numbers. In RNG of digits from 1 to 6, 19 patients with left-sided neglect generated sequences with a higher redundancy, but as many small numbers as did a matched control group. We discuss possible reasons for the absence of a small-number neglect and emphasize that the observed redundancy was not due to a counting bias, as known from other neurological patients, but to an unspecific imbalance in the use of response alternatives. We speculate that this may be the consequence of disrupted fronto-parietal functions normally serving in the sequential organization and manipulation of items in working memory.

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confidence: 51%

Random number generation in neglect patients reveals enhanced response stereotypy, but no neglect in number space

Loetscher

Brugger

2009

Neuropsychologia

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“…Recently, Loetscher, Schwarz, Schubiger, and Brugger (2008b) found that turning one's head to the left or right modulated random number generation; specifically, right head turning Numerical Attention and Distance 4 led to larger numbers being generated more frequently than did left head turning. These results provide an intriguing demonstration of a relation between attention to numerical information and the position and orientation of body parts with respect to each other.…”

Section: Introductionmentioning

confidence: 99%

Bisecting the mental number line in near and far space

Longo

Lourenco

2010

Brain and Cognition

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Much evidence suggests that common posterior parietal mechanisms underlie the orientation of attention in physical space and along the mental number line. For example, the small leftward bias (pseudoneglect) found in paper-and-pencil line bisection is also found when participants "bisect" number pairs, estimating (without calculating) the number midway between two others.For bisection of physical lines, pseudoneglect has been found to shift rightward as lines are moved from near space (immediately surrounding the body) to far space. We investigated whether the presentation of stimuli in near or far space also modulated spatial attention for the mental number line. Participants bisected physical lines or number pairs presented at four distances (60, 120, 180, 240 cm). Clear rightward shifts in bias were observed for both tasks. Furthermore, the rate at which this shift occurred in the two tasks, as measures by least-squares regression slopes, was significantly correlated across participants, suggesting that the transition from near to far space induced a common modulation of lateral attention in physical and numerical space. These results demonstrate a tight coupling between number and physical space, and show that even such prototypically abstract concepts as number are modulated by our on-line interactions with the world.

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“…Thus, SNB could be a consequence of a cerebral hemispheric imbalance in favour of righthemisphere spatial-attentional functions. Support for the latter account of SNB comes from experiments during which human subjects were required to turn their head laterally while generating numbers "at random" (Loetscher, Schwarz, Schubiger, & Brugger, 2008). …”

Section: Introductionmentioning

confidence: 99%

Asymmetric prefrontal cortex functions predict asymmetries in number space

Bachmann

Fischer

Landolt

et al. 2010

Brain and Cognition

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Asymmetric prefrontal cortex functions predict asymmetries in number spaceBachmann, V; Fischer, M H; Landolt, H P; Brugger, P Bachmann, V; Fischer, M H; Landolt, H P; Brugger, P (2010 AbstractLittle is known about the neuropsychological factors that contribute to individual differences in the asymmetric orientation along the mental number line. The present study documents healthy subjects' preference for small numbers over large numbers in a random number generation task. This preference, referred to as "small number bias" (SNB), varied with prefrontal functional lateralization: it was larger in participants with over-proportionately better performance in design fluency compared to letter fluency than in participants with overproportionately better performance in letter fluency when compared to design fluency.Asymmetries in learning and memory tasks (verbal vs. non-verbal) were not related to direction or size of the SNB. We conclude that hemispheric asymmetries of specifically prefrontal executive functions are predictive of an individual's lateral orientation bias along the mental number line. Therefore, the focus on parietal contributions to spatial-numerical associations may not be justified. Random number generation may be a helpful method to further explore these associations uncontaminated by the asymmetric involvement of response effectors.

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Head turns bias the brain's internal random generator

Cited by 161 publications

References 15 publications

Random number generation in neglect patients reveals enhanced response stereotypy, but no neglect in number space

Random number generation in neglect patients reveals enhanced response stereotypy, but no neglect in number space

Bisecting the mental number line in near and far space

Asymmetric prefrontal cortex functions predict asymmetries in number space

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