Working Memory Load Affects Processing Time in Spoken Word Recognition: Evidence from Eye-Movements.

Britt Hadar,Joshua E Skrzypek,Boaz M Ben-David,Arthur Wingfield

doi:10.3389/fnins.2016.00221

Abstract

In daily life, speech perception is usually accompanied by other tasks that tap into working memory capacity. However, the role of working memory on speech processing is not clear. The goal of this study was to examine how working memory load affects the timeline for spoken word recognition in ideal listening conditions. We used the “visual world” eye-tracking paradigm. The task consisted of spoken instructions referring to one of four objects depicted on a computer monitor (e.g., “point at the candle”). Half of the trials presented a phonological competitor to the target word that either overlapped in the initial syllable (onset) or at the last syllable (offset). Eye movements captured listeners' ability to differentiate the target noun from its depicted phonological competitor (e.g., candy or sandal). We manipulated working memory load by using a digit pre-load task, where participants had to retain either one (low-load) or four (high-load) spoken digits for the duration of a spoken word recognition trial. The data show that the high-load condition delayed real-time target discrimination. Specifically, a four-digit load was sufficient to delay the point of discrimination between the spoken target word and its phonological competitor. Our results emphasize the important role working memory plays in speech perception, even when performed by young adults in ideal listening conditions.

Highlights

Seemingly performed without effort, understanding speech is a complex task (Pollack and Pickett, 1963; Lindblom et al, 1992; Wingfield et al, 1994; Murphy et al, 2000)
The goal of the current study was to examine the extent to which working memory load affects the timeline for the processing of a single spoken word
Increasing the working memory load from one to four digits might increase the competition generated by the shared final phonemes. We suggest that this increase in competition might shift speech processing from implicit to more explicit, delaying the onset of fixations on the target word

Summary

Introduction

Seemingly performed without effort, understanding speech is a complex task (Pollack and Pickett, 1963; Lindblom et al, 1992; Wingfield et al, 1994; Murphy et al, 2000). During the process of spoken-word recognition, listeners must simultaneously retain and process the context of the sentence, keep the previous spoken words activated, segregate the speech signal from noise, and inhibit the potential activation of alternatives for the spoken word (e.g., phonetic or semantic). All of these operations might draw on the same resources necessary for speech processing and, as a result, may compromise recognition. The current study presents, to the best of our knowledge, the first examination of the impact of working memory load on the online processing of a single spoken word in ideal listening conditions For this purpose, we examined eye-movements using the visual. Working Memory and Word Recognition world paradigm (Tanenhaus et al, 1995) to reveal listeners’ timeline for recognition of target words.

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