Lee, S.-s., & Dobson, L. N. (1977). From referents to symbols: Visual cues and pointing effects on children's acquisition of linear function rules. Journal of Educational Psychology, 69(5), 620-629.
http://dx.doi.org/10.1037/0022-0663.69.5.620
Each of 84 children in Grade 4 and combined Grades 5–6 first learned 2 linear function rules (a × F = S and F + b = S) under 1 of 7 conditions. These conditions resulted from variations in 2 factors: pointing (presence vs absence) and visual cues (context vs weight vs both pictured) plus a verbal-only baseline condition. Subsequently, Ss learned a complex rule (a × F + b = S) as a transfer task. Those trained with the visual cues abstracted a rule from rule instances and expressed it in symbols more easily than did the others. The visual cues caused positive transfer to the abstraction and the symbolic expression of the complex rule. The pointing activity had a short-term effect for the initial acquisition only, but it in itself retarded transfer. (PsycINFO Database Record (c) 2016 APA, all rights reserved)