Your Therapy Source Magazine for Pediatric Therapists December 2015 | Page 8

SNARC Effect and Motor Responses
Have you ever heard of the SNARC effect? I had not, so when I read about it in a research
article I decided to find out more information. SNARC stands for spatial-numerical
association of response codes. The SNARC effect is when someone is presented with
smaller numbers people respond faster with the left hand and when presented with larger
numbers people respond faster with the right. This results in an mental representation of a
number line. Some research indicates that the SNARC effect is present in children as young
as 5.8 years old. Preschool children are developing the SNARC effect.
In one study, 4 year olds participated in a spatial search task with a box that had seven
compartments labeled with the numerals 1 to 7. For half of the children the numbers
increased from left to right, and for the other half the numbers increased from right to left. The
results showed that children were faster and more accurate in the left-to-right search
condition. In a second experiment, the researchers asked preschool children (3–5 years of
age) to count a given linear set of objects. The results indicated that already 73% of the
preschoolers started counting at the leftmost object and proceeded to the rightmost object.
Another study involving 4-year-olds discovered that the children were faster when choosing
the display containing less elements when it was presented on the left side of the screen and
more elements when presented on the right side of the screen.
Additional research (Crollen, 2015) indicates that children with non verbal learning disabilities
(NVLD) do not display the SNARC effect. NVLD seems to affect the accuracy and the nature
of the mental number line by decreasing the saliency of its left-to-right orientation.
Another study (Lindemann, 2007), revealed a close link between numerical cognition and
motor control. The researchers discovered that precision grip actions were initiated faster in
response to relatively small numbers, whereas power grip actions were initiated faster in
response to large numbers. Interestingly, numerical magnitudes did not affect the actions if
they involved no grasping component and consisted only of a reaching movement (i.e.,
pointing response) toward the smaller or larger (respective upper or lower) part of the object.
Therefore, reaction time effects remained present when controlling for the number of fingers
used while grasping but disappeared when participants pointed to the object.
Do you take numerical magnitude into consideration when working on visual spatial tasks with
children? If you do, does it improve the child’s accuracy? I would be very interested in
seeing additional research on this topic especially with the children that receive school based
therapy services, exhibit visual perceptual deficits or any children with motor planning deficits.
References:
Crollen, V. et.al Spatial and numerical processing in children with non-verbal learning disabilities. Research in
Developmental Disabilities. Volume 47, December 2015, Pages 61–72
Hoffmann, D et al. Developing number–space associations: SNARC effects using a color discrimination task in
5-year-olds. Journal of Experimental Child Psychology
Volume 116, Issue 4, December 2013, Pages 775–791
Lindemann, O et al. Getting a grip on numbers: numerical magnitude priming in object grasping. J Exp Psychol
Hum Percept Perform 2007 Dec;33(6):1400-9

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