When the mind's eye prevails: The Internal Dominance over External Attention (IDEA) hypothesis.

Throughout the 20th century, the psychological literature has considered attention as being primarily directed at the outside world. More recent theories conceive attention as also operating on internal information, and mounting evidence suggests a single, shared attentional focus between external and internal information. Such sharing implies a cognitive architecture where attention needs to be continuously shifted between prioritizing either external or internal information, but the fundamental principles underlying this attentional balancing act are currently unknown. Here, we propose and evaluate one such principle in the shape of the Internal Dominance over External Attention (IDEA) hypothesis: Contrary to the traditional view of attention as being primarily externally oriented, IDEA asserts that attention is inherently biased toward internal information. We provide a theoretical account for why such an internal attention bias may have evolved and examine findings from a wide range of literatures speaking to the balancing of external versus internal attention, including research on working memory, attention switching, visual search, mind wandering, sustained attention, and meditation. We argue that major findings in these disparate research lines can be coherently understood under IDEA. Finally, we consider tentative neurocognitive mechanisms contributing to IDEA and examine the practical implications of more deliberate control over this bias in the context of psychopathology. It is hoped that this novel hypothesis motivates cross-talk between the reviewed research lines and future empirical studies directly examining the mechanisms that steer attention either inward or outward on a moment-by-moment basis.

Attentional switching between perception and memory: Examining asymmetrical switch costs.

Attention can be defined as a mechanism for the selection and prioritization of elements among many. When attention is directed to a specific piece of information, this information is assumed to be in the focus of attention. On a day-to-day basis, we need to rely on efficient switching between information we are holding in working memory (internal modality) and information presented in the world around us (external modality). A recent set of studies investigated between-modality attentional switches and found that there is an asymmetrical switch cost for switching between the internal and external focus of attention (Verschooren et al., 2020, Journal of Experimental Psychology: Human Perception and Performance, 46[9], 912-925; Verschooren, Liefooghe, et al., 2019a, Journal of Experimental Psychology: Human Perception and Performance, 45[10], 1399-1414). In particular, participants switched on a trial-by-trial basis between an internal task using stimuli retrieved from memory and an external task using on-screen presented stimuli. A larger cost was found when switching from the external modality towards the internal modality than the other way around. The authors found that this cost asymmetry could be best explained in terms of associative interference (i.e., differences in shielding efficiency against the memory traces from the competing task set). The present study aimed to replicate the asymmetrical switch cost (Experiment 1) and investigate whether an alternative explanation in terms of stimulus strength can account for the asymmetrical switch cost (Experiment 2). Overall, the results confirm the presence of a subtle, asymmetrical switch cost, but we observed little to no contribution of stimulus strength.

Early reduction of sensory processing within the visual cortex when switching from internal to external attention.

The neurocognitive process underlying attention switches between external (perception-based) and internal (memory-based) attention is poorly characterized. Previous research has found that when participants switch attention either between two perception-based tasks (within-domain switches) or between a memory- and a perception-based task (between-domain switches), a substantial and similar processing cost was observed compared to the repetition of the same task (Verschooren, Schindler, De Raedt, & Pourtois, 2019). Here, we recorded 64-channel EEG while participants carried out within- versus between-domain switches of attention. ERP results showed that during early sensory processing, a marked P1 attenuation was associated with both switch types, suggesting that switching was associated with an early bottleneck during information processing. This early gating effect was stronger when switching from an internal to an external task, compared to switching between external tasks, suggesting different top-down requirements for them. These findings are in line with earlier proposals in the literature.

Evidence for a single mechanism gating perceptual and long-term memory information into working memory.

An influential view of working memory (WM) holds that its contents are controlled by a selective gating mechanism that allows for relevant perceptual information to enter WM when opened, but shields WM contents from interference when closed. In support of this idea, prior studies using the reference-back paradigm have established behavioral costs for opening and closing the gate between perception and WM. WM also frequently requires input from long-term memory (LTM), but it is currently unknown whether a similar gate controls the selection of LTM representations into WM, and how WM gating of perceptual vs. LTM sources of information relate to each other. To address these key theoretical questions, we devised a novel version of the reference-back paradigm, where participants switched between gating perceptual and LTM information into WM. We observed clear evidence for gate opening and closing costs in both cases. Moreover, the pattern of costs associated with gating and input source-switching indicated that perceptual and LTM information is gated into WM via a single gate, and rely on a shared source-selection mechanism. These findings extend current models of WM gating to encompass LTM information, and outline a new functional WM architecture.

More efficient shielding for internal than external attention? Evidence from asymmetrical switch costs.

At present, the process of switching attention between external stimuli and internal representations is not well understood. To address this, Verschooren, Liefooghe, Brass, and Pourtois (2019) recently designed a novel paradigm where participants were cued to switch attention between external and internal information on a trial-by-trial basis. The authors observed an asymmetrical switch cost, which was larger when switching toward internal than external material, even though participants performed internal trials faster. In the current study, we sought to establish the cause of this asymmetry by adjudicating among predictions from three theoretical accounts: associative interference, priming, and memory retrieval. After replicating the original asymmetry (Experiment 1), we demonstrated that trial-by-trial carryover of attentional settings is not a necessary precondition (Experiment 2). The results from Experiment 3 indicate that the cost asymmetry can be best explained by an associative interference account, against a memory retrieval one. Together, these results therefor provide evidence in favor of an associative interference account and document that shielding attention for internal representations from external intrusions is more efficient than the other way around. This finding advances our understanding of a core aspect of cognitive flexibility and the relationship between external and internal attention. More research on this question and novel ones raised by it are necessary, however. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Bidirectional cingulate-dependent danger information transfer across rats.

Social transmission of freezing behavior has been conceived of as a one-way phenomenon in which an observer "catches" the fear of another. Here, we use a paradigm in which an observer rat witnesses another rat receiving electroshocks. Bayesian model comparison and Granger causality show that rats exchange information about danger in both directions: how the observer reacts to the demonstrator's distress also influences how the demonstrator responds to the danger. This was true to a similar extent across highly familiar and entirely unfamiliar rats but is stronger in animals preexposed to shocks. Injecting muscimol in the anterior cingulate of observers reduced freezing in the observers and in the demonstrators receiving the shocks. Using simulations, we support the notion that the coupling of freezing across rats could be selected for to more efficiently detect dangers in a group, in a way similar to cross-species eavesdropping.

Attentional flexibility is imbalanced: Asymmetric cost for switches between external and internal attention.

Whereas the effects of attention switches occurring within perception or memory are relatively well understood, much less is known about switches of attention between them. We discuss the methodological limitations of initial research on this topic, which was never integrated with the broader cognitive literature. On the basis of this discussion, we present here a new paradigm, in which participants performed a simple probe-to-target matching task where targets were either perceived on screen or retrieved from memory. Across successive trials, repetitions or alternations (in both directions) between these 2 conditions were created, and eventually compared with each other. In line with our prediction, derived from the assumption of a top-down control mechanism, we found a cost for switching between external and internal attention in Experiment 1. Furthermore, this switch cost was asymmetric, being substantially larger when switching from (external) perception to (internal) memory than the other way around. In Experiments 2-4, we ruled out an imbalance in practice, learning, and preparation as confounds for this asymmetry. We propose that switches of attention between internal and external information are underpinned by a supervisory attention control mechanism, and that this asymmetry can be explained in terms of priming, associative interference or memory retrieval. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Switching attention from internal to external information processing: A review of the literature and empirical support of the resource sharing account.

Despite its everyday ubiquity, not much is currently known about cognitive processes involved in flexible shifts of attention between external and internal information. An important model in the task-switching literature, which can serve as a blueprint for attentional flexibility, states that switch costs correspond to the time needed for a serial control mechanism to reallocate a limited resource from the previous task context to the current one. To formulate predictions from this model when applied to a switch between perceptual attention (external component) and working memory (WM; internal component), we first need to determine whether a single, serial control mechanism is in place and, subsequently, whether a limited resource is shared between them. Following a review of the literature, we predicted that a between-domain switch cost should be observed, and its size should be either similar or reduced compared to the standard, within-domain, switch cost. These latter two predictions derive from a shared resource account between external and internal attention or partial independence among them, respectively. In a second phase, we put to the test these opposing predictions in four successive behavioral experiments by means of a new paradigm suited to compare directly between- (internal to external) and within- (external to external) domain switch costs. Across them, we demonstrated the existence of a reliable between-domain switch cost whose magnitude was similar to the within-domain one, thereby lending support to the resource-sharing account.