Verbal Working Memory Load Dissociates Common Indices of the Numerical Distance Effect: Implications for the Study of Numerical Cognition

Verbal Working Memory Load Dissociates Common Indices of the Numerical Distance Effect: Implications for the Study of Numerical Cognition

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Title 

Verbal Working Memory Load Dissociates Common Indices of the Numerical Distance Effect: Implications for the Study of Numerical Cognition  

Authors 

Maloney, E., Barr, N., Risko, E., Fugelsang, J. (2019) 

Journal and DOI 

Journal: Journal of Numerical Cognition, 5(3) 

DOI: https://doi.org/10.5964/jnc.v5i3.155 

Previous Research 

Working Memory (WM) plays an essential role in various types of mathematical processing.  

The most frequently studied phenomenon in numerical comparison is the Numerical Distance Effect (NDE). The NDE states that when comparing two numbers, participants are faster and more precise at indicating which of the numbers is larger when the numerical distance between the compared digits is relatively large (e.g., 2 and 9) than small (e.g., 8 and 6).  

Most research focuses on the role of a person’s working memory while they are performing mathematical operations, such as addition and subtraction.  

What did we ask? 

How does verbal working memory impact the NDE in simultaneous comparison tasks (presenting participants with 2 numbers simultaneously and asking them to identify the larger one)? 

How does verbal working memory impact the NDE in tasks that involve comparison to a standard (I.e., comparing numbers to the number 5)? 

How did we do it? 

We conducted 4 experiments involving simultaneous comparison tasks and “comparison to a standard” tasks: 

Experiment 1: 53 participants completed “simultaneous comparison” tasks (pairs were generated between the numbers 1-4 and 6-9) and “comparison to a standard” tasks, under 2 blocked WM load conditions (0 load to high load).  

Experiment 2: 60 participants performed both tasks under zero and high verbal WM loads. They had to compare squares that varied in physical size and identify the larger one.  

Experiment 3: 45 participants carried out a simultaneous comparison task, where the numbers 1, 4, 6 and 9 were paired with the number 5.  

Experiment 4: 78 participants had to compare various numbers to the number 5 and state whether it was higher or lower than 5. However, in this experiment they were also reminded of the standard number 5 at the beginning of every trial. 

What did we find? 

The results of all 4 experiments support the hypothesis that verbal WM is involved in symbolic numerical comparison.  

High verbal WM loads disrupt the processes that lead to the NDE.  

The effect of verbal WM load on numerical comparison is dependent upon the nature of the task.  

During “simultaneous comparison” tasks, the NDE decreases as the WM load increases. 

During “comparison to a standard” tasks, the NDE increases as the WM load increases.  

Take Away Message 

In each of the number comparison tasks, there were distinct correlations found between WM load and NDE. This is significant, since existing research suggested that these two tasks involved the same underlying mechanisms.  

This study encourages further research on long-term comparison strategies (in “comparison to a standard” tasks) and short-term comparison strategies (in “simultaneous comparison” tasks) 

Brought to you by Dr. Erin Maloney’s Cognition and Emotion Lab at the University of Ottawa