Are parity and magnitude status of Arabic digits processed automatically? An EEG study using the fast periodic visual stimulation

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Alexandre Poncin

1

*, Amandine Van Rinsveld

1

, Mathieu Guillaume

1

, Bruno Rossion

2

, Christine Schiltz

1

.

1

Cognitive Science and Assessment Institute, ECCS unit, University of Luxembourg, Luxembourg

2

Institute Of Neuroscience, Université catholique de Louvain, Belgium

*

Corresponding author: alexandre.poncin@uni.lu

Are parity and magnitude status of Arabic digits processed

automatically? An EEG study using the fast periodic visual stimulation.

Magnitude represented by number symbols is automatically processed in the right parie-tal cortex of healthy human adults (Cohen Kadosh & al. 2012; Tzelgov & al., 1992)

Magnitude is processed faster than parity (Dehaene, Bossini, & Giraux, 1993).

Magnitude is processed automatically during parity jugement task (Dehaene & al 1993).

Introduction

We expected:

1) A significant oddball both for the magnitude and the parity conditions but not for the control condition, reflecting automatic magnitude and parity processing.

2) A right lateralization of the responses in both the magnitude and the parity conditions.

Hypotheses

Sixteen young adults (9 males; Mean age = 24 years old).

First, we averaged the signal of the 4 repetitions for each condition. Then we averaged both of the pari-ty and the magnitude conditions respectively (Average: odd-even + even-odd ; small-large +

large-small).

Acquisition system: BioSemi ActiveTwo system with 128 channels at 1024Hz .

Methods

Fast Periodic Visual Stimulation

Signal-to-noise ratio and topography

The three tasks activated the same area of the right and left parietal cortex. Nevertheless, oddball responses were stronger in the magnitude condition than in the other two conditions. Those results are consistent with the existing literature:

1) Magnitude processing involves the right and left parietal area (Cohen Kadosh, Bien, & Sack, 2012; Tzelgov, Meyer, & Henik, 1992).

2) The weaker response over the right parietal cortex during the parity task could be caused by slower processing due to the need of magnitude retrieval before accessing the parity status of the number (Dehaene, Bossini, & Giraux, 1993).

3) The response over the left and right parietal cortex during the control task could be caused by the fact that subjects can quickly learn to categorize numbers even if their categorization is done arbitrarily.

Conclusion

Control

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4

Magnitude

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Parity

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Cohen Kadosh, R., Bien, N., & Sack, A. T. (2012). Automatic and Intentional Number Processing Both Rely on Intact Right Parietal Cortex: A Combined fMRI and Neuronavigated TMS Study. Frontiers in Human Neuroscience, 6, 2. https://doi.org/10.3389/fnhum.2012.00002 Dehaene, S., Bossini, S., & Giraux, P. (1993). The mental representation of parity and number magnitude. Journal of Experimental Psychology: General, 122(3), 371–396. https://doi.org/10.1037/0096-3445.122.3.371

Tzelgov, J., Meyer, J., & Henik, A. (1992). Automatic and intentional processing of numerical information. Journal of Experimental Psychology: Learning, Memory, and Cognition, 18(1), 166–179. https://doi.org/10.1037/0278-7393.18.1.166

1 second

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9

9

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Stimuli were continuously displayed trough

sinusoïdal contrast modulation, during four sessions of 60 seconds.

We varied stimulus font, size and position

around the fixation cross in order to avoid visual bias

Stimuli presentation

Conditions Frequent stimuli Oddball stimuli Oddball frequency Number of repetitions

Base frequency

Parity Odd (1-3-7-9) Even (2-4-6-8) 1.25Hz (1/8 stimuli) 10Hz (10 stimuli/second) 4

Parity Even (2-4-6-8) Odd (1-3-7-9) 1.25Hz (1/8 stimuli) 10Hz (10 stimuli/second) 4

Magnitude Small (1-2-3-4) Large (6-7-8-9) 1.25Hz (1/8 stimuli) 10Hz (10 stimuli/second) 4

Magnitude Large (6-7-8-9) Small (1-2-3-4) 1.25Hz (1/8 stimuli) 10Hz (10 stimuli/second) 4

Control No rules (1-4-6-9) No rules (2-3-7-8) 1.25Hz (1/8 stimuli) 10Hz (10 stimuli/second) 4

C

ONTR

OL

PARITY

MA

GNITUDE

Comparison of the left and right parietal activations

-0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

CONTROL PARITY MAGNITUDE

B a se li n e va lu e Conditions

Left parietal electrodes

-0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

CONTROL PARITY MAGNITUDE

B a se li n e va lu e Conditions

Figure

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