The Spatial-Numerical Association of Response Codes (SNARC) effect in highly math-anxious individuals: An ERP study

Response inhibition deficits in math-anxious individuals

We examined whether math anxiety is related to a response inhibition deficit and, if so, whether it is a domain-specific inhibition deficit in numerical tasks or a general inhibition deficit. Behavioral performance and electroencephalogram activity were recorded while 28 highly math-anxious (HMA) and 28 low math-anxious (LMA) individuals performed both a numerical and a non-numerical Go/Nogo task. In the numerical task, single-digit numbers were presented, and participants were asked to press a button if the number was even. In the non-numerical task, letters were presented, and the button had to be pressed if the letter was a vowel. Nogo trials were answered less accurately and elicited larger Nogo-N2 and Nogo-P3 than Go trials in both tasks and both groups. Importantly, behavioral and brain response differences between tasks were only found in the HMA group. First, they were more error-prone in numerical Nogo than in non-numerical Nogo trials; and second, their Nogo-N2 and N2d (Nogo-Go difference) were smaller in the numerical task than in the non-numerical task. No differences were found in the LMA group. These results suggest that HMA individuals' response inhibition is impaired specifically when dealing with numbers, which could contribute to their low achievement in math tasks.

Stronger spatial bias induced more by numbers in mind than numbers in eye: Evidence from event-related potentials

The relationship between number and space is an important issue in numerical cognition. The spatial-numerical association of response codes (SNARC) effect is a classic example of the association between numbers and spaces. It refers to the phenomenon whereby left-handed responses occur faster to small number and right-handed responses occur faster to large number. The current study explored the shared and distinct neural correlates of the SNARC effect considering numbers in eye and numbers in mind, by using event-related potentials (ERPs) technology. In each trial of the task, participants were asked to press freely one of two keys as a response to a number presented visually (numbers in eye) or via imagination (numbers in mind). The behavioral results indicated that the free-choice key presses were affected by the magnitudes of the numbers either in eye or in mind. Electrophysiological results observed that the SNARC effect appeared only in the 110 - 140 ms time window for numbers in eye. In contrast, for numbers in mind, the SNARC effect appeared during a longer time window (110 - 330 ms). These results suggest that both, numbers in eye and numbers in mind, can induce spatial bias at the early stimulus-representation stage, but the time duration of the spatial bias is longer for numbers in mind than numbers in eye. This may reflect a closer connection between numbers in mind and mental number line.

The role of cognitive control in the SNARC effect: A review

The spatial-numerical association of response codes (SNARC) effect, in which people respond to small numbers faster with the left hand and to large numbers faster with the right hand, is a popular topic in cognitive psychology. Some well-known theoretical accounts explaining this effect include the mental number line model, polarity correspondence principle, dual-route model, and working memory account. However, these fail to explain the finding that the size of the SNARC effect is modulated by cognitive control. Here, we propose a new account-a cognitive control-based view of the SNARC effect. This view argues that the SNARC effect is fundamentally determined by cognitive control in resolving conflicts during stimulus-response mapping. Several subcomponents of cognitive control, such as working memory, mental or task set shifting, inhibition control, and conflict adaptation, can easily modulate the SNARC effect. The cognitive control-based view can account for the flexible SNARC effect observed in diverse task situations while providing new insight into its mechanism.