The time-course of distractor-based activation modulates effects of speed-accuracy tradeoffs in conflict tasks

The cognitive processes underlying the ability of human performers to trade speed for accuracy is often conceptualized within evidence accumulation models, but it is not yet clear whether and how these models can account for decision-making in the presence of various sources of conflicting information. In the present study, we provide evidence that speed-accuracy tradeoffs (SATs) can have opposing effects on performance across two different conflict tasks. Specifically, in a single preregistered experiment, the mean reaction time (RT) congruency effect in the Simon task increased, whereas the mean RT congruency effect in the Eriksen task decreased, when the focus was put on response speed versus accuracy. Critically, distributional RT analyses revealed distinct delta plot patterns across tasks, thus indicating that the unfolding of distractor-based response activation in time is sufficient to explain the opposing pattern of congruency effects. In addition, a recent evidence accumulation model with the notion of time-varying conflicting information was successfully fitted to the experimental data. These fits revealed task-specific time-courses of distractor-based activation and suggested that time pressure substantially decreases decision boundaries in addition to reducing the duration of non-decision processes and the rate of evidence accumulation. Overall, the present results suggest that time pressure can have multiple effects in decision-making under conflict, but that strategic adjustments of decision boundaries in conjunction with different time-courses of distractor-based activation can produce counteracting effects on task performance with different types of distracting sources of information.

Eye movements through space interfere with visual processing of time-related words

When people make lexical decisions to words referring to the past or the future, they are faster when their manual responses are compatible with the mental timeline (MTL). That is, future words are responded to faster on the right than the left, while past words are responded to faster on the left than the right. This space-time congruency effect is interpreted to suggest that time words are represented along a spatial continuum that goes from left to right (past to future), at least in Western cultures that use reading-writing systems operating from left to right. All previous experiments used lateralized hand movements to register responses, which would evoke the directionality of writing. To evoke the directionality of reading, we investigated whether the space-time congruency effect would be replicated in a language task when responses were given using the eyes rather than the hand. Thus, participants were asked to make lateralized eye movements to indicate whether letter stimuli were real words or not (lexical decision). Eye movements were perturbed for responses incompatible with the direction of the MTL, both in terms of decision time and motor amplitude. These results confirm that time-related words are embodied through spatial movement in effector-independent motor networks and suggests that the spatial representation of time operates in a body-centered reference frame.

Number to me, space to you: Joint representation of spatial-numerical associations

Recent work has shown that number concepts activate both spatial and magnitude representations. According to the social co-representation literature which has shown that participants typically represent task components assigned to others together with their own, we asked whether explicit magnitude meaning and explicit spatial coding must be present in a single mind, or can be distributed across two minds, to generate a spatial-numerical congruency effect. In a shared go/no-go task that eliminated peripheral spatial codes, we assigned explicit magnitude processing to participants and spatial processing to either human or non-human co-agents. The spatial-numerical congruency effect emerged only with human co-agents. We demonstrate an inter-personal level of conceptual congruency between space and number that arises from a shared conceptual representation not contaminated by peripheral spatial codes. Theoretical implications of this finding for numerical cognition are discussed.

Neuronal congruency effects in macaque frontal cortex

The interplay between task-relevant and task-irrelevant stimulus features induces conflicts which impair human behavioral performance in many perceptual and cognitive tasks, a.k.a. a behavioral congruency effect. The neuronal mechanisms underlying behavioral congruency effects, however, are poorly understood. We recorded single unit activity in monkey frontal cortex using a novel task-switching paradigm and discovered a neuronal congruency effect that is carried by task-relevant and -irrelevant neurons. The former neurons provide more signal, the latter less noise in congruent compared to incongruent conditions. Their relative activity levels determine the neuronal congruency effect and behavioral performance. Although these neuronal congruency signals are sensitive to selective attention, they cannot be entirely explained by selective attention as gauged by response time. We propose that such neuronal congruency effects can explain behavioral congruency effects in general, as well as previous fMRI and EEG results in various conflict paradigms.

When two languages are competing

Past studies have shown that expert interpreters were better than novices at using contextual cues to anticipate upcoming information. However, whether such sensitivity to contextual cues can be traced by means of neural signatures is relatively unexplored. The present study used event-related brain potentials (ERPs) along with a language-switching paradigm – including non-switched (Chinese–Chinese, L1–L1) and switched (Chinese–English, L1–L2) conditions – to investigate whether interpreters with many years of experience, interpreters with a few years of experience and post-graduate-level interpreting students differed in the way they process contextually congruent or incongruent sentence-final target words. The results show that while the manipulations of congruency and switching independently induced a strong brain response in all three groups, the interaction between the two factors elicited different patterns across groups during 500–700 ms: (1) while a sustained congruency effect was found in the two less-experienced groups for the switched condition, such an effect was observed in the most experienced group for both switched and non-switched conditions; (2) only the least-experienced group showed a frontal negativity towards incongruent trials in the switched condition. These 200 ms transient group differences revealed that it might be possible to trace the development of interpreting ability by examining the ERP components in a language-switching setting.

Proportion of Conflict, Contingency Learning, and Recency Effects in a Stroop Task

Recent research on the relation between learning and cognitive control has assumed that conflict modulates learning, either by increasing arousal and hence improving learning in high conflict situations (Verguts & Notebaert, 2008), or by inducing control, and hence inhibiting the processing of distracters and their eventual association with the imperative responses (Whitehead et al., 2018). We analyze whether the amount of conflict, manipulated through the proportion of congruency in a set of Stroop inducer trials, affects learning of contingencies established on diagnostic trials composed by neutral words associated with color responses. The results reproduced the list-wide proportion of congruency effect on the inducer trials, and showed evidence of contingency learning on the diagnostic trials, but provided no indication that this learning was modulated by the level of conflict. Specific analyses conducted to control for the impact of episodic effects on the expression of learning indicated that contingency effects were not driven by the incremental processes that could be expected by associative learning, but rather they were due to the impact of the most recent trial involving the same distracter. Accordingly, these effects disappeared when tested selectively on trials that required a non-matching response with respect to the previous occurrence of the distracter. We interpret this result in the context of the debate on how learning and memory interact with the processes of cognitive control.

What can size tell us about abstract conceptual processing?

Embodied cognition theories propose that abstract concepts can be embodied via metaphorical extensions from experiences of the physical or the mental worlds. In three experiments, we explored how semantic size (e.g., the magnitude, dimension or extent of an object or a concept) of abstract concepts is mentally represented. We show that abstract size is metaphorically associated with the physical size of concrete objects (Experiment 1) and can produce a semantic-font size congruency effect comparable to that demonstrated in concrete words during online lexical processing (Experiment 2). Critically, this size congruency effect is large when a word is judged by its size but significantly smaller when it is judged by its emotionality (Experiment 3). Our results suggest that semantic size of abstract concepts can be represented in physical size and that such experiences are variably engaged under different task demands. The present findings advocate flexible embodiment of semantic representations, with an emphasis on the role of task effects on conceptual processing.