Facing the future: memory as an evolved system for planning future acts

Abstract

All organisms capable of long-term memory are necessarily oriented toward the future. We propose that one of the most important adaptive functions of long-term episodic memory is to store information about the past in the service of planning for the personal future. Because a system should have especially efficient performance when engaged in a task that makes maximal use of its evolved machinery, we predicted that future-oriented planning would result in especially good memory relative to other memory tasks. We tested recall performance of a word list, using encoding tasks with different temporal perspectives (e.g., past, future) but a similar context. Consistent with our hypothesis, future-oriented encoding produced superior recall. We discuss these findings in light of their implications for the thesis that memory evolved to enable its possessor to anticipate and respond to future contingencies that cannot be known with certainty.

Figure 1

Mean ratings of 18 stimulus words with respect to their relevance to going on a camping trip. Scale values ranged from 1 (not at all ) to 5 (very much).

Figure 2

Mean ratings of 18 stimulus words with respect to their relevance to planning a camping trip. Scale values ranged from 1 (not at all) to 5 (very much).

Figure 3

Mean recall of stimulus words (maximum possible = 30 words) as a function of encoding task.

Figure 4

Mean likeliness ratings of stimulus words as a function of encoding task. Scale values ranged from 1 (very unlikely) to 5 (very likely).

Figure 5

Mean ease of rating stimulus words as a function of encoding task. Scale values ranged from 1 (very hard) to 5 (very easy).