Training alters the resolution of lexical interference: Evidence for plasticity of competition and inhibition

Abstract

Language learning is generally described as a problem of acquiring new information (e.g., new words). However, equally important are changes in how the system processes known information. For example, a wealth of studies has suggested dramatic changes over development in how efficiently children recognize familiar words, but it is unknown what kind of experience-dependent mechanisms of plasticity give rise to such changes in real-time processing. We examined the plasticity of the language processing system by testing whether a fundamental aspect of spoken word recognition, lexical interference, can be altered by experience. Adult participants were trained on a set of familiar words over a series of 4 tasks. In the high-competition (HC) condition, tasks were designed to encourage coactivation of similar words (e.g., net and neck) and to require listeners to resolve this competition. Tasks were similar in the low-competition (LC) condition, but did not enhance this competition. Immediately after training, interlexical interference was tested using a visual world paradigm task. Participants in the HC group resolved interference to a fuller degree than those in the LC group, demonstrating that experience can shape the way competition between words is resolved. TRACE simulations showed that the observed late differences in the pattern of interference resolution can be attributed to differences in the strength of lexical inhibition. These findings inform cognitive models in many domains that involve competition/interference processes, and suggest an experience-dependent mechanism of plasticity that may underlie longer term changes in processing efficiency associated with both typical and atypical development.

Figure 1

Examples of trials for the phoneme monitoring task for the high-competition (HC) group (a) and low-competition (LC) group (b).

Figure 2

Examples of trials for the same/different task for the high-competition (HC) group (a) and low-competition (LC) group (b).

Figure 3

Examples of trials for the spoken to written word matching task for the high-competition (HC) group (a) and low-competition (LC) group (b).

Figure 4

Examples of trials for the primed production task for the high-competition (HC) group (a) and low-competition (LC) group (b).

Figure 5

Proportion of looks to the target per splice condition for the high-competition (HC) group (a) and the low-competition (LC) group (b). Time 0 ms indicates the trial onset. RT = reaction time. ^* Marker on the x-axis adjusted by 200 ms to account for oculomotor delay plus 50 ms for silence added to stimulus onset.

Figure 6

Interference curves per group (solid lines: fitted data; dotted lines: observed data). Gray shadows represent error bars for the jackknifed/curve-fitted data. RT = reaction time; HC = high-competition; LC = low-competition. ^* Marker on the x-axis adjusted by 200 ms to account for oculomotor delay plus 50 ms for silence at stimulus onset.

Figure 7

Proportion of looks to the target in the matching-splice (a) and word-splice (b) conditions per group. RT = reaction time; HC = high-competition; LC = low-competition. ^* Marker on the x-axis adjusted by 200 ms to account for oculomotor delay plus 50 ms of silence at stimulus onset.

Figure 8

Matching-splice (a) and word-splice (b) as presented in TRACE. Dotted lines mark the beginning and end of coarticulatory mismatch.

Figure 9

Interference effect (i.e., target activation in matching-minus word-splice; see Figure 8) in jTRACE simulations as a function of lexical inhibition. Dotted lines mark the beginning and end of coarticulatory mismatch for the word-splice condition.

Figure 10

Target activation, when it is spliced with itself (matching-splice; panel a) and when it is spliced with the competitor (word-splice; panel b) as a function of inhibition level. Dotted lines mark the beginning and end of coarticulatory mismatch for the word-splice condition.

Figure 11

Competitor activation when the target is spliced with the competitor (i.e., word-splice) as a function of lexical inhibition. Dotted lines mark the beginning and end of coarticulatory mismatch for the word-splice condition.