The effect of retention interval upon hemispheric processes in recognition memory.

Simple concrete nouns were presented unilaterally in a continuous recognition memory procedure. Each word was presented twice in a session, and subjects were required to signal the second occurrence of a word. Retention interval was manipulated by varying the lag separating word presentations, and lags of 1, 4, 8, and 32 items were employed in the design. Words were projected, on first and second presentations respectively, to the following visual fields: LL, LR, RR, and RL. No visual field effects were observed at lag 1, but an advantage for RVF probes was evident from lag 4 onwards. At lag 8, a relative superiority emerged from uncrossed versus crossed presentation. The results support the idea that lateral asymmetries develop as processing engages deeper and more complex levels of representation. There was also evidence that memory representations are more salient following direct, rather than transcallosal, stimulation of a hemisphere.