engleski

Brightness perception affects mental arithemtic

According to a theory of magnitude, all quantitative dimensions (space, time, number, brightness, etc.) share common magnitude representation in the parietal cortex. Consistent with this theory, previous studies revealed interaction between number magnitude and brightness. We hypothesized that similar interaction should exist between brightness and mental arithmetic if mental arithmetic is performed by movements along the common magnitude representation. Participants were asked to verify whether the left-hand side of simple arithmetic statements such as 2 + 5 = 7 or 9 - 6 = 5, equals the right-hand side result. Arithmetic problems appeared either in black or white on a gray background. Each problem involved two operands in the range 2 to 9 and yielded results in the ranges 4 to 18 for addition and from 0 to 7 for subtraction problems. 18 addition and 18 subtraction equations appeared twice as a true problem (once in black and once in white color) and twice as a false problem (once in black and once in white color) resulting in a total of 144 trials. Thirty- one undergraduate psychology students participated in an exchange for course credits. The order of the presentation of problems within each block was randomized across the participants. Analysis of verification times revealed statistically significant threeway interaction between brightness, arithmetic operation and response, F(1, 30) = 16.90, p<.001, partial eta2 = .36. Addition problems were verified faster in white color relative to black when the correct response was Yes, but they were verified slower in white when the correct response was No. On the other hand, subtraction problems were verified faster in black color relative to white when the correct response is Yes but slower in black when the correct response is No. In Experiment 2, we employed the same method with another group of thirty psychology students to show that the same result held for word problems (e.g., SEVEN + SIX = THIRTEEN), that is, we found the same three-way interaction between brightness, arithmetic operation and response, F(1, 29)=59.59, p<.001, η 2=.67. Furthermore, Experiment 3 showed that when participants performed multiplication and division, there was no evidence for a three-way interaction between brightness, arithmetic operation and response, F(1, 23)=2.15, p=.156, partial η 2=.09. Results showed that the speed of mental calculation is modulated by brightness, providing further support for the theory of magnitude.

brightness perception ; grounded cognition ; magnitude representation ; mental arithmetic ; mental number line

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