Evidence for disproportionate dual-task costs in older adults for episodic but not semantic memory

Previous research demonstrates that older adults are poor at dual tasking, but there is less agreement on whether their decrement is worse than that predicted from single-task performance. This study investigated whether task domain moderates dual-task costs in old age. In two experiments, young and older adults retrieved either previously learned associates (episodic retrieval) or overlearned category members (semantic retrieval) under single or working-memory load conditions, using cued recall (Experiment 1) and recognition (Experiment 2) procedures. In both experiments the proportional costs of dual tasking were age invariant for semantic retrieval but were particularly marked for episodic retrieval, although the size of the age effect was reduced in recognition compared to cued recall. The data suggest that age effects in dual tasking may be domain specific.     

Evidence against a predictive role for rhythm in speech perception

Some languages create the impression of being stress timed. Claims have been made that this timing of stressed syllables enables the listener to predict the future locations of informative parts later in a sentence. The fact that phoneme monitoring is delayed when targets in a spoken sentence are displaced has been taken as supporting this claim (Meltzer, Martin, Bergfeld Mills, Imhoff and Zohar, 1976). In the present study temporal displacement was induced without introducing phonetic discontinuities. In Dutch sentences a word just in advance of a target-bearing word was replaced by another one differing in length. Results show that the temporal displacement per se did not have any effect on phoneme-monitoring reaction times. Implications for a theory of fpeech processing are discussed.     

Delayed-matching-to-sample by marsh tits and great tits

The ability of two species of tits to remember the location and/or features of an object was tested in a delayed-matching-to-sample procedure. Three values of retention interval between presentation of the sample stimulus and the choice--30 sec, 5 min, and 15 min--were used. Both species performed at above-chance level at all retention intervals, and there was no significant decline in accuracy with increasing interval. A pool of 100 stimulus objects was used, but the results of control trials indicated that the birds responded primarily to location rather than stimulus features of the object itseif. Although the food-storing marsh tit tended to perform at a higher level than the non-storing great tit, the only significant difference between the species was in the first 50 trials of the first treatment, when the birds were acquiring the task. The results are discussed in relation to the hypothesized special memory capacity of food-storing birds.