Adults' strategy choices for simple addition: Effects of retrieval interference

Simple addition (e.g., 3 + 2, 7 + 9) may be performed by direct memory retr ieval or by such procedures as counting or transformation. The distribution of associations (DOA) model of strategy choice (Siegler, 1988) predicts th at procedure use should increase as retrieval interference increases. To te st this, 100 undergraduates performed simple addition problems, either afte r blocks of simple multiplication (high-interference context) or after bloc ks of simple division problems (low-interference context). Addition took lo nger and was more error prone after multiplication; in particular, there we re more multiplication confusion errors on the relatively easy, small-numbe r addition problems (e.g., 3 + 2 = 6, 4 + 3 = 12), but not on the more diff icult, large-number additions. Consistent with the DOA, participants report ed greater use of procedures for addition after multiplication, but more so for small addition problems. The findings demonstrate that adults' use of procedural strategies for simple addition is substantially influenced by re trieval interference.