Does being bilingual sharpen thinking, or is it really about SES?
Socioeconomic status predicted executive-task performance far more strongly than bilingualism, and bilinguals were actually worse at a planning task.
Source
The Importance of Socioeconomic Status as a Modulator of the Bilingual Advantage in Cognitive Ability
Study at a glance
- Design
- Cross-sectional — Quasi-experimental 2 (language group) x 2 (SES) between-subjects comparison; Simon task congruency manipulated within subjects.
- N
- N=90 · 90 young adults: 45 monolingual and 45 bilingual, each split into 20 low-SES and 25 high-SES participants.
- Population
- Adults aged 18-30 in London; low-SES participants from a vocational college (low-SES bilinguals were first-generation immigrants), high-SES from university and professional settings.
- Outcome
- Simon task response time and accuracy; Tower of London accuracy, first-move (planning) time and total trial time.
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What they did
The researchers tested 90 young adults in four groups: monolinguals and bilinguals, each drawn from low and high socioeconomic backgrounds, with groups matched on age, non-verbal reasoning and digit span. Everyone did a Simon task, where you respond to a star's colour while ignoring which side it appears on, and a computerised Tower of London planning puzzle. The Simon task had 36 trials and the Tower of London had twelve problems of rising difficulty.
What they found
SES had a large effect: high-SES participants responded faster on the Simon task and solved more Tower of London problems. Bilinguals showed only a marginal overall speed advantage on the Simon task, and it did not depend on whether the trial involved conflict, so it does not look like better inhibition; the speed benefit appeared mainly in the low-SES group. On the Tower of London, monolinguals were more accurate and faster to plan than bilinguals, and low-SES bilinguals did especially poorly.
The limits
What it doesn't show
Groups were not randomly assigned, and low-SES bilinguals were immigrants (half with refugee or asylum status), so language status is tangled up with migration, trauma and schooling history. Cell sizes were small (20-25 per group) and the Simon task had few trials with no practice, which limits reliability; the authors call for larger studies with more trials. The findings cover two tasks in young adults in one city and do not show what causes the SES or language effects.
Key terms
- Simon effect
- Slower responses when a stimulus appears on the side opposite to the required response key, reflecting conflict between location and the response rule.
- Bilingual advantage hypothesis
- The claim that managing two languages trains general executive functions such as inhibition or monitoring.
- Socioeconomic status (SES)
- A person's social and economic standing, here judged from employment, education and income.
- Tower of London
- A puzzle in which discs must be rearranged to match a target in a set number of moves, used to measure planning.
- Confound
- A variable that differs between groups alongside the variable of interest and could explain the result instead.
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Quiz yourself
What was the largest influence on Simon task response speed?
Common questions
Does this prove bilingualism is bad for thinking?
No. The planning disadvantage appeared in groups that also differed in migration history and background, so it cannot be attributed to language alone.
Why does SES matter so much in this debate?
If bilingual samples happen to be richer or better educated than monolingual ones, any 'bilingual advantage' could really be an SES advantage. Here SES produced much larger effects than language group.
Why is it important that the bilingual speed benefit was similar on congruent and incongruent trials?
An inhibition advantage should show up mainly on conflict trials; a general speed-up instead points to broader monitoring or other factors.
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