On the nature of talker variability effects on recall of spoken word lists

Abstract

In a recent study, Martin, Mullennix, Pisoni, and Summers (1989) reported that subjects' accuracy in recalling lists of spoken words was better for words in early list positions when the words were spoken by a single talker than when they were spoken by multiple talkers. The present study was conducted to examine the nature of these effects in further detail. Accuracy of serial-ordered recall was examined for lists of words spoken by either a single talker or by multiple talkers. Half the lists contained easily recognizable words, and half contained more difficult words, according to a combined metric of word frequency, lexical neighborhood density, and neighborhood frequency. Rate of presentation was manipulated to assess the effects of both variables on rehearsal and perceptual encoding. A strong interaction was obtained between talker variability and rate of presentation. Recall of multiple-talker lists was affected much more than single-talker lists by changes in presentation rate. At slow presentation rates, words in early serial positions produced by multiple talkers were actually recalled more accurately than words produced by a single talker. No interaction was observed for word confusability and rate of presentation. The data provide support for the proposal that talker variability affects the accuracy of recall of spoken words not only by increasing the processing demands for early perceptual encoding of the words, but also by affecting the efficiency of the rehearsal process itself.

Figure 1

Mean percentages of correctly recalled words as a function of (a) serial position and talker condition, collapsed across presentation rate and word confusability, and (b) serial position and word confusability, collapsed across presentation rate and talker.

Figure 2

Mean percentages of correctly recalled words for both the single- and multiple-talker lists as a function of serial position and presentation rate, collapsed across word confusability. The five panels display the results at each rate of presentation, one word every (a) 250 ms, (b) 500 ms, (c) 1,000 ms, (d) 2,000 ms. and (e) 4,000 ms. Open squares represent single-talker lists; filled squares represent multi-talker lists.

Figure 3

Mean percentages of correctly recalled words for both the easy and hard word lists as a function of serial position and presentation rate, collapsed across talker. The five panels display the results at each rate of presentation, one word every (a) 250 ms, (b) 500 ms, (c) 1,000 ms (d) 2,000 ms, and (e) 4,000 ms. Open squares represent easy lists; filled squares represent hard lists.