Procedural-Memory, Working-Memory, and Declarative-Memory Skills Are Each Associated With Dimensional Integration in Sound-Category Learning

Abstract

This paper investigates relationships between procedural-memory, declarative-memory, and working-memory skills and adult native English speakers' novel sound-category learning. Participants completed a sound-categorization task that required integrating two dimensions: one native (vowel quality), one non-native (pitch). Similar information-integration category structures in the visual and auditory domains have been shown to be best learned implicitly (e.g., Maddox et al., 2006). Thus, we predicted that individuals with greater procedural-memory capacity would better learn sound categories, because procedural memory appears to support implicit learning of new information and integration of dimensions. Seventy undergraduates were tested across two experiments. Procedural memory was assessed using a linguistic adaptation of the serial-reaction-time task (Misyak et al., 2010a,b). Declarative memory was assessed using the logical-memory subtest of the Wechsler Memory Scale-4th edition (WMS-IV; Wechsler, 2009). Working memory was assessed using an auditory version of the reading-span task (Kane et al., 2004). Experiment 1 revealed contributions of only declarative memory to dimensional integration, which might indicate not enough time or motivation to shift over to a procedural/integrative strategy. Experiment 2 gave twice the speech-sound training, distributed over 2 days, and also attempted to train at the category boundary. As predicted, effects of declarative memory were removed and effects of procedural memory emerged, but, unexpectedly, new effects of working memory surfaced. The results may be compatible with a multiple-systems account in which declarative and working memory facilitate transfer of control to the procedural system.

Keywords: cognition; individual differences; language acquisition; memory; speech-sound learning.

FIGURE 1

Sequence of events for Experiments 1 and 2. Experiment 1 was completed on 1 day, while Experiment 2 was completed over 2 days.

FIGURE 2

Synthesized speech stimuli varied in pitch (F0) and second-formant frequency (F2). Solid and dashed circles indicate two different sets of stimuli along the category boundary that were presented at the start of each training day in Experiment 2, but were intermixed with other stimuli in Experiment 1.

FIGURE 3

Within-trial sequence for each category-learning trial.

FIGURE 4

Example trial showing the grid of word stimuli displayed on the computer screen. The cursors (added for emphasis) point to the target string in each third of the trial (pel, wadim, rud, underlined for emphasis). The other three words are foils (vot benez jic).

FIGURE 5

Scatterplot, with best-fit line, depicting the impact of declarative-memory skills on number of linear blocks in Experiment 1. In a regression analysis that also included procedural-memory skills and working-memory skills as predictors, declarative-memory skills were the only significant predictor.

FIGURE 6

Scatterplot, with best-fit line, depicting the impact of procedural-memory skills on Block 6 accuracy in Experiment 2, day 1. In a regression analysis that also included declarative-memory skills and working-memory skills as predictors, procedural-memory skills were the only significant predictor.

FIGURE 7

Scatterplot, with best-fit line, depicting the impact of working-memory skills on number of linear blocks in Experiment 2, day 1. In a regression analysis that also included declarative-memory skills and procedural-memory skills as predictors, working-memory skills were the only significant predictor.

FIGURE 8

Scatterplot, with best-fit line, depicting the impact of working-memory skills on Block 6 accuracy in Experiment 2, day 2. In a regression analysis that also included declarative-memory skills and procedural-memory skills as predictors, working-memory skills were the only significant predictor.

FIGURE 9

Scatterplot, with best-fit line, depicting the impact of procedural-memory skills on number of linear blocks in Experiment 2, day 2. In a regression analysis that also included declarative-memory skills and working-memory skills as predictors, procedural-memory skills were the only significant predictor.