Influential ‘fast-and-slow’ dual process models suggest that sound reasoning requires the correction of fast, intuitive thought processes by slower, controlled deliberation. Recent findings with high-level reasoning tasks started to question this characterization. Here we tested the generalizability of these findings to low-level cognitive control tasks. More specifically, we examined whether people who responded accurately to the classic Stroop and Flanker tasks could also do so when their deliberate control was minimized. A two-response paradigm, in which people were required to give an initial ‘fast’ response under time–pressure and cognitive load, allowed us to identify the presumed intuitive answer that preceded the final ‘slow’ response given after deliberation. Across our studies, we consistently find that correct final Stroop and Flanker responses are often non-corrective in nature. Good performance in cognitive control tasks seems to be driven by accurate ‘fast’ intuitive processing, rather than by ‘slow’ controlled correction of these intuitions. We also explore the association between Stroop and reasoning performance and discuss implications for the dual process view of human cognition.

This study investigates bilingualism-induced neuroplastic and cognitive-reserve effects in the Caudate Nucleus (CN), a structure believed to support both bilingual language control and domain-general executive functioning. We computed a generalized bilingualism index incorporating several dimensions of bilingual experience in a sample of bilingual young adults and tested whether this index would predict behavioral executive performance (measured using a Flanker task) and volumetric differences in the CN. Moreover, we investigated whether bilingualism mitigates the relationship between CN volume and executive performance, a sign of cognitive reserve. Our results indicate that bilingualism facilitates executive performance and induces an inverted U-shaped neuroplastic trajectory in bilateral CN, consistently with the view that structural increases are replaced by functional improvements as bilingual experience progresses. The emergence of bilingualism-induced cognitive reserve effects in CN further supports the view that bilinguals rely progressively less on the availability of structural resources in the face of increased functional efficiency.

In two experiments, we examined the hypothesis that bilingual speakers modulate their cognitive control settings dynamically in the presence of different interlocutors, and this can be captured through performance on a non-linguistic attention task. We introduced Malayalam–English bilinguals to interlocutors with varying L2 dominance through a pre-experiment familiarisation and interaction phase. Later, participants did the Flanker task while the interlocutors appeared before each trial. While in experiment one participants did the Flanker task with equal distribution of trials, in experiment two we manipulated the monitoring demands by changing the frequency of trials. Results showed that high-L2 proficient bilinguals had lower conflict effect on the Flanker task in the presence of balanced interlocutors in both the experiments. The results provide strong evidence of dynamic adaptation of control settings in bilinguals with regard to different passively present interlocutors. The results further extend the predictions of the adaptive control hypothesis with novel manipulation.

Both bilingualism and attention contribute to the development of executive functioning (EF), with higher levels of both leading to better outcomes. The present study treats bilingualism and attention as continuous variables to investigate their impact on EF. Eighty-two 9-year-olds who were attending a French school in an anglophone community completed a flanker task. Children's progress in French represented their level of bilingualism, and attention was assessed through a standard standardized instrument. Degree of bilingualism and degree of attention were both positively related to performance, but exposure to a third language in the home did not further affect outcomes.

The question of whether bilingualism conveys a broader advantage in executive functions has recently been controversially discussed, with the empirical findings presenting a complex pattern of positive and null results. Here we present results from three standard tasks measuring executive functions (Flanker; Simon; Spatial Stroop) in which we compared performance of English monolingual to Chinese–English bilingual young adults. Participants provided responses via movement of a computer mouse rather than the conventional key presses, which provides a rich signal of the unfolding response dynamics. Clear differences between bi- and monolinguals emerged, with the former providing more ‘efficient’ responses than the latter. Results are discussed regarding the extent to which these results can be characterised as a genuine “bilingual advantage”.

Fourteen children with attention-deficit hyperactivity disorder (ADHD) and 14 normal control children were compared with respect to stimulus- and response-related processes. Subjects with ADHD took part in two additional sessions under methylphenidate or placebo. In both experiments, performance and electrophysiological measures such as the P2, N2, and P3 components of event-related potential and electromyogram (EMG) activity were measured during an Eriksen flanker task. In both groups of children, reaction times (RTs) to arrow stimuli incongruent with the target were longer than those to neutral stimuli (response interference), which were again slower than RTs to target-alone stimuli (perceptual interference). Children with ADHD made more errors to incongruent stimuli and showed more response interference. For correct responses, no differences between the groups in response interference effects on reaction time, P2, N2, and P3 latency, or EMG onset were found. Methylphenidate had a general enhancing effect on accuracy but did not specifically reduce interference from the flanking stimuli. Methylphenidate had no effects on RT, N2 and P2 latency, P3 amplitude or latency, or EMG activity. The conclusion that methylphenidate did not influence response processes contrasts sharply with findings reported by authors using the Sternberg memory search task.