Spacing effects on implicit picture memory

25 undergraduates studied the stimulus pictures of common objects successively presented as spaced or massed repetitions, or one at a time. Immediately after a study period, they were given a free-recall test followed by a perceptual identification test. Analysis indicated that spacing effects were observed on the free-recall test but not in perceptual identification. On the later test, each stimulus picture was exposed for a short period and subjects were more likely to use perceptual cues than on first the test. Thus, the spacing effects on memory may be eliminated at test as there is no benefit of conceptual cues.