Poster E106, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Discrimination of Magnitudes within Different Dimensions: A Developmental Trajectory Outline
Shai Itamar1, Avishai Henik1,2; 1Department of Psychology and the Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel, 2Department of Cognitive and Brain Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
According to the approximate number system (ANS) theory, non-symbolic magnitude dimensions are represented in a noisy manner that results in an approximation of a given magnitude. Moreover, in the ANS, discriminability of magnitudes complies with Weber's law so that in a magnitude comparison task, the relationship between the magnitude ratio and reaction time (RT) should be linear. The assumption that discriminability of all magnitudes complies with Weber's law was questioned. It was found that in a magnitude comparison task, the relationship between discriminability and size ratio is not always linear. Namely, this relationship is modulated by the type of the stimuli. While physical magnitude comparison results in a curve-linear fit, symbolic magnitude comparison results in a linear fit. In this study, we explored the developmental changes that occur in the ability to discriminate magnitudes in young children (1st, 3rd and 5th graders). We employed a power function to describe the relationship between magnitude ratio and RT in different magnitude comparison tasks (symbolic, continuous and discrete). Results indicated that for physical comparison, the function exponent (b-value) was the highest, though it slightly decreased from the 3rd to the 5th grade. For discrete comparison, the function exponent increased with age. For symbolic comparison, the function exponent remained slightly increased from the 1st to the 3rd grade. These results support previous findings indicating that the relationship between discriminability and magnitude ratio is not always linear. Moreover, the results indicate that the different magnitude dimensions undergo different developmental trajectories regarding their representation and discrimination.
Topic Area: PERCEPTION & ACTION: Development & aging