Failure of working memory training to enhance cognition or intelligence.

Todd W Thompson,Patricia Chang,John D E Gabrieli,Carlos Cardenas-Iniguez,Nupur Lala,Kiersten Pollard,Gretchen O Reynolds,Keri-Lee A Garel,Rebecca Winter,George A Alvarez,Michael L Waskom,Hans P O P De Beeck

doi:10.1371/journal.pone.0063614

Abstract

Fluid intelligence is important for successful functioning in the modern world, but much evidence suggests that fluid intelligence is largely immutable after childhood. Recently, however, researchers have reported gains in fluid intelligence after multiple sessions of adaptive working memory training in adults. The current study attempted to replicate and expand those results by administering a broad assessment of cognitive abilities and personality traits to young adults who underwent 20 sessions of an adaptive dual n-back working memory training program and comparing their post-training performance on those tests to a matched set of young adults who underwent 20 sessions of an adaptive attentional tracking program. Pre- and post-training measurements of fluid intelligence, standardized intelligence tests, speed of processing, reading skills, and other tests of working memory were assessed. Both training groups exhibited substantial and specific improvements on the trained tasks that persisted for at least 6 months post-training, but no transfer of improvement was observed to any of the non-trained measurements when compared to a third untrained group serving as a passive control. These findings fail to support the idea that adaptive working memory training in healthy young adults enhances working memory capacity in non-trained tasks, fluid intelligence, or other measures of cognitive abilities.

Highlights

A fundamental question of both theoretical and practical interest is whether the basic human cognitive abilities that underlie many aspects of learning, memory, thinking, and performance can be enhanced in adults
Of particular importance for the hypothesized transfer from the dual n-back task to more general cognition, a participants’ initial performance on the dual n-back task was significantly correlated with fluid intelligence measures (Ravens Advanced Progressive Matrices and the Wechsler Abbreviated Scale of Intelligence (WASI) Matrix Task), complex working memory measures (Operation Span, Reading Span, and their combined score), and a reading comprehension measure (Nelson-Denny Reading Comprehension)
The major finding was a failure to observe any gains in measured fluid intelligence after working memory training

Summary

Introduction

A fundamental question of both theoretical and practical interest is whether the basic human cognitive abilities that underlie many aspects of learning, memory, thinking, and performance can be enhanced in adults. Because standardized intelligence quotient (IQ) scores predict performance on a wide range of cognitive tasks and educational achievements [1], IQ scores are often used as an index of general cognitive abilities Such IQ measures exhibit substantial correlations from late childhood through adulthood (e.g., IQ scores were estimated to correlate 0.73 from ages 11 through 77 in a longitudinal study [2]). These observations suggest that variation in general cognitive abilities is determined, to a large extent, by late childhood or early adolescence This fixedness of cognitive ability has seemed especially strong for fluid intelligence (the ability to solve novel problems), relative to crystallized intelligence (the ability to apply specific knowledge, skills, and experience). In part this is because scores on tests of crystallized intelligence can be improved by, for example, instructing a student on the vocabulary that the crystallized intelligence tests typically evaluate, and in part because fluid intelligence has typically been considered as more biologically determined than crystallized intelligence [3,4]

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