A test of precategorical and attentional explanations of speech suffix interference

It is well-known that a redundant item or “stimulus suffix”, which does not have to be recalled, which is spoken, and which terminates the presentation of a beyond span-length sequence of to-be-remembered (TBR) spoken items, will generate considerable interference in immediate serial recall. Previous work has established that speech suffix interference is not influenced by a number of intrinsic attributes of the suffix. A limitation of this work, however, is the fact that in each study there has been little if any disparity between TBR sequence and suffix in terms of extrinsic attributes. Experiment I extends this work and showed that at least one intrinsic attribute of the suffix (personal significance) has no effect on suffix interference when there is also a marked disparity between TBR sequence and suffix in terms of one specific extrinsic attribute (spatial location). Experiment II simply served to eliminate one possible artifactual explanation of this finding. The result appears to have some theoretical importance since it is inconsistent with Kahneman's (1973) attentional account of suffix interference and with one interpretation of a precategorical hypothesis due to Morton, Crowder and Prussin (1971).