Some conditions for the occurrence of the bizarreness effect in free recall

Existing literature on bizarreness effects in verbal learning mainly focuses on the common assumption that bizarre images are easier to recall than common ones. In so doing, however, researchers have obtained more negative than positive results. Further, among the few investigations that found this effect three used the same procedure and the same material in which a bizarre relationship between subject and object was achieved by substituting human beings for animals and vice versa. It was observed that a clear bizarreness effect may still be observed if inanimate sentences are constructed in accordance with the same principle of distorting typical relations (Expt 1). This effect remains, albeit in a milder form, when aspects of the original procedure are manipulated, such as eliminating complementary sentences (Expt 2) or abstract sentences (Expt 3) from the lists. This seems to demonstrate that the traditional opinion that bizarre images make the mnemonic task easier is, at least in part, true. Nevertheless, if one uses the procedure used by Merry & Graham (1978) and others with semantically unpredictable sentences, the bizarreness effect was attenuated and even normal sentences sometimes achieved higher scores (Expt 4). In general, these results reveal that bizarre sentences are more likely to result in better recall as regards number of nouns remembered, whereas the opposite is true as regards number of complete sentences remembered. This is consistent with the view that recall of normal sentences is facilitated by the unitization. These four experiments carried out with adult subjects demonstrate the generality of the bizarreness effect and some of the factors which contribute to it.