Probe recall and short-term memory: Some evidence for nonlinear search strategies.

The subjects saw sequences of three, five, or seven digits. A subsequent probe test signaled subjects to respond with the item that had followed (forward probe) or preceded (backward probe) the probe item in the sequence. Regardless of probe direction, correct reaction times increased linearly as a function of list length. Correct reaction time as a function of serial position yielded nonlinear curves, suggesting that subjects did not search memory serially in a forward direction. Instead, the shapes of these functions suggested response strategies which involved multiple entry or anchor points and backward search through short-term memory.