Lexical and Frequency Effects on Keystroke Timing: Challenges to a Lexical Search Account From a Type-To-Copy Task

Laurie Beth Feldman,Jacolien Van Rij,Rick Dale

doi:10.3389/fcomm.2019.00017

Abstract

We explore how timing in identical keystroke sequences of a stem morpheme is influenced by linguistic knowledge by manipulating lexical status and morphological complexity of words in a type-to-copy task. Starting from the second keystroke, we find that average keystroke latency within a stem morpheme varies according to whole-word frequency (Experiment1) and lexicality defined by compatibility of the upcoming suffix (e.g., IZE vs IST) with the stem (e.g., NORMAL) to form a string (e.g., RENORMALIZE vs. RENORMAL; RENORMALIZE vs. RENORMALIST in Experiments 2 & 3 respectively). Further, although lexical and frequency effects persist over the string as a whole, nonlinear mixed-effects regressions reveal position varying lexical effects on keystroke latencies within the stem morpheme. In addition, whole word frequency effects on the first keystroke were present. These results challenge hierarchical accounts of production with modular motor programs where the same letter sequence (for a morpheme) is realized independently of and only after lexical access to the word in which the letters occur (cf. Crump & Logan, 2010; Logan & Crump 2011).

Highlights

In most accounts of language processing it is assumed that access to one’s knowledge about a word is stored in a mental lexicon and that lexical access to activate the requisite linguistic knowledge is necessary to execute behavior relevant to particular experimental tasks
Results such as these highlight some of the ways in which processing of the stem is interdependent with that of the affixes with which it co-occurs. We examine this interaction in more detail below because it may identify a potential weakness of an account of morphological processing restricted to the stem, and an account of typing where keystrokes are executed in series irrespective of emerging lexical or non-lexical context based on the particular combination of morphemes which accompany the stem
In the framework where the mental lexicon is treated as a repository of lexical knowledge and access to it is conceptualized as all or none, time to access knowledge about a particular word will vary across words due to frequency and this effect of whole word frequency gets reflected in the layout or organization of word representations in the lexicon

Summary

Introduction

In most accounts of language processing it is assumed that access to one’s knowledge about a word is stored in a mental lexicon and that lexical access to activate the requisite linguistic knowledge is necessary to execute behavior relevant to particular experimental tasks. In this framework, the mental lexicon is treated as a repository of lexical knowledge and access based on orthographic or phonological form generally is conceptualized as all or none. The knowledge that underlies productive and receptive language use reflects the typicality and distinctiveness of the meaning and form-based properties of a word with respect to context (e.g., other words). Interdependent orthographic, phonological, lexical and semantic properties that emerge over time are essential, and form the basis for a more dynamic lexical framework that involves extensive interactivity (cf. Seidenberg and McClelland, 1989)

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