Prefrontal neuromodulation reverses spatial associations of non-numerical sequences, but not numbers

Schroeder, Philipp A.; Nuerk, Hans‐Christoph; Plewnia, Christian

doi:10.1016/j.biopsycho.2017.07.008

Cited by 18 publications

(46 citation statements)

References 102 publications

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“…Specifically, in this previous study, participants displayed the reverse orientation for a SNARC effect for weekday stimuli (that is, Monday and Tuesday were faster responded to with their right hands, while Thursday and Friday were responded faster to with their left hands) when stimulated with anodal tDCS, but not with cathodal tDCS. For the group stimulated with anodal tDCS, we thus observed a striking reversal of the spatial association of a non-numerical sequence in the same two-choice reaction time testing paradigm, highlighting a dissociation between numerical and non-numerical sequential (weekday) spatial associations (Schroeder et al, 2017b ).…”

Section: Introductionmentioning

confidence: 65%

“…In a follow-up study, we investigated whether stimulation effects were specific for numbers or whether the polarity-specific tDCS effects would generalize to non-numerical sequence items. Having established a valid sham-control for modulations of spatial associations of numbers in the first study, we now tested different SNARC effects in a more economic parallel design with two groups of participants who performed baseline assessments (without tDCS) immediately followed by 1 mA anodal or cathodal tDCS applied concurrent to a second assessment of task performance (Schroeder et al, 2017b ). The cardinal number sequence included number symbols 1, 2, 4, and 5, and the ordinal non-numerical sequence included written weekday names Monday, Tuesday, Thursday, and Friday (in German).…”

Section: Introductionmentioning

confidence: 99%

“…Such magnitude associations may have been pronounced in the Huber study particularly because a within-subject manipulation of number range could have drawn attention to number magnitude information. However, this same mechanism hardly accounts for reversed spatial associations of weekdays during anodal tDCS (Schroeder et al, 2017b ), because retrieval of weekday spatial associations from long-term memory should also yield a left-to-right oriented SNARC effect in Western participants, but not a reversed one.…”

Section: Introductionmentioning

confidence: 99%

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Switching between Multiple Codes of SNARC-Like Associations: Two Conceptual Replication Attempts with Anodal tDCS in Sham-Controlled Cross-Over Design

2017

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In societies with left-to-right reading direction, left-side vs. right-side behavioral decisions are faster for relatively small vs. large number magnitudes, and vice versa, a phenomenon termed Spatial-Numerical Associations of Response Codes (SNARC) effect. But also for non-numerical sequential items, SNARC-like effects were observed, suggesting a common neurocognitive mechanism based on the ordinal structures of both numbers and sequences. Modulation of prefrontal networks that are involved in providing spatial associations during cognitive behavior can contribute to elaborate their neuropsychological theoretical foundations. With transcranial direct current stimulation (tDCS) directed to the left prefrontal cortex, we recently showed that (i) cathodal tDCS can block the emergence of spatial-numerical associations and that (ii) anodal tDCS can reverse spatial associations of sequential order, most likely based on markedness correspondence. Two conceptual replication attempts of the latter reversal of space-order associations are presented in the current sham-controlled experiment, using either weekdays (Monday-Friday) or month names (January-December) as stimuli in the temporal order classification task. In addition, to control for possible influences of notation, number stimuli were presented as written German names (One-Five). We report on a successful modulation of spatial-numerical associations of response codes (SNARC) effects with month stimuli induced by anodal tDCS, but failed to observe the same reversal of SNARC effects for weekday stimuli. The former stimulation effect was orthogonal to the small anodal tDCS effect on written number words, which replicates the dissociation of SNARC effects for numbers vs. non-numerical sequences. Moreover, this result reinforces the hypothesis that the ordinal item and task structure was the source of dissociation (as opposed to verbal presentation). We suggest that the diverging results can be explained by the markedness correspondence account of spatial associations in a multiple coding framework. Left-hemispheric prefrontal excitation from anodal tDCS renders verbal markedness relatively more dominant, but this effect is not absolute. We discuss task contagion, study design, and individual differences in performance measures or tDCS response as possible contributors to systematic variation of the weights of multiple coding parameters for spatial-numerical associations.

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Section: Introductionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Switching between Multiple Codes of SNARC-Like Associations: Two Conceptual Replication Attempts with Anodal tDCS in Sham-Controlled Cross-Over Design

2017

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“…From the previous IAT studies, it remained possible that a reduction of prefrontal activity may actually prove beneficial, as it was already shown for creative tool use (Chrysikou et al, 2013) and other behaviors . Actually, in previous studies on numerical cognition, we demonstrated that implicit spatial-numerical associations can be reduced specifically by 1 mA cathodal tDCS (Schroeder, Nuerk, & Plewnia, 2017;Schroeder, Pfister, Kunde, Nuerk, & Plewnia, 2016). However, although implicit spatial-numerical associations can be documented also in IAT double-classification tasks (Fischer & Shaki, 2016), implicit spatial-numerical biases are typically probed using much simpler stimulus-response compatibility paradigms in two-alternatives forced-choice classifications (e.g., judging whether a number is smaller or greater than B5,^or another reference number) by means of a left-hand or right-hand key press.…”

Section: Authorsmentioning

confidence: 76%

Reduction of implicit cognitive bias with cathodal tDCS to the left prefrontal cortex

Schroeder

Nuerk

Plewnia

2018

Cogn Affect Behav Neurosci

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Implicit associations can interfere with cognitive operations and behavioral decisions without direct intention. Enhancement of neural activity with anodal transcranial direct current stimulation (tDCS) was proposed to reduce implicit associations by means of improved cognitive control. However, a targeted reduction of distractive implicit associations by inhibitory cathodal tDCS, recently shown in spatial-numerical associations, provides an interesting alternative approach to support goal-directed behavior with transcranial brain stimulation. To test this rationale with a sham-controlled cross-over design, a standardized Implicit Association Test (IAT) was performed by 24 healthy participants parallel to 1 mA cathodal or sham tDCS to the left prefrontal cortex. In this double-classification task, insect versus flower pictures and negative versus positive words are mapped together onto two shared response keys with crossed response assignments in separate blocks. Responses were faster when insect + negative and flower + positive stimuli required the same answer (IAT effect). Most critically, the IAT effect was reduced during cathodal tDCS as compared to sham stimulation. Thus, results are consistent with the proposed stimulation rationale, with previous observations, and complementary to previous studies using different tDCS configurations.

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“…Reverse SNARC-like effect for ordinal non-numerical sequences (e.g., weekdays) under transcranial direct current stimulation (Schroeder, Nuerk & Plewnia, 2017a) also challenges the WM account, but mixed evidence emerged for such effect (Schroeder, Nuerk & Plewnia, 2017b). Since the spatial orientation is not a feature of the long-term memory representation but rather emerges from short-term association in working memory, the level of processing required by the task should not affect the strength of the SNARC effect.…”

Section: Introductionmentioning

confidence: 99%

The influence of semantic processing and response latency on the SNARC effect

2019

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Prefrontal neuromodulation reverses spatial associations of non-numerical sequences, but not numbers

Cited by 18 publications

References 102 publications

Switching between Multiple Codes of SNARC-Like Associations: Two Conceptual Replication Attempts with Anodal tDCS in Sham-Controlled Cross-Over Design

Switching between Multiple Codes of SNARC-Like Associations: Two Conceptual Replication Attempts with Anodal tDCS in Sham-Controlled Cross-Over Design

Reduction of implicit cognitive bias with cathodal tDCS to the left prefrontal cortex

The influence of semantic processing and response latency on the SNARC effect

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