Model-based Cognitive Neuroscience: Multifield Mechanistic Integration in Practice

Autonomist accounts of cognitive science suggest that cognitive model building and theory construction (can or should) proceed independently of findings in neuroscience. Common functionalist justifications of autonomy rely on there being relatively few constraints between neural structure and cognitive function (e.g., Weiskopf, 2011). In contrast, an integrative mechanistic perspective stresses the mutual constraining of structure and function (e.g., Piccinini & Craver, 2011; Povich, 2015). In this paper, I show how model-based cognitive neuroscience (MBCN) epitomizes the integrative mechanistic perspective and concentrates the most revolutionary elements of the cognitive neuroscience revolution (Boone & Piccinini, 2016). I also show how the prominent subset account of functional realization supports the integrative mechanistic perspective I take on MBCN and use it to clarify the intralevel and interlevel components of integration

Perceptual Pluralism

Perceptual systems respond to proximal stimuli by forming mental representations of distal stimuli. A central goal for the philosophy of perception is to characterize the representations delivered by perceptual systems. It may be that all perceptual representations are in some way proprietarily perceptual and differ from the representational format of thought (Dretske 1981; Carey 2009; Burge 2010; Block ms.). Or it may instead be that perception and cognition always trade in the same code (Prinz 2002; Pylyshyn 2003). This paper rejects both approaches in favor of perceptual pluralism, the thesis that perception delivers a multiplicity of representational formats, some proprietary and some shared with cognition. The argument for perceptual pluralism marshals a wide array of empirical evidence in favor of iconic (i.e., image-like, analog) representations in perception as well as discursive (i.e., language-like, digital) perceptual object representations

Temporal Brain Dynamics of Multiple Object Processing: The Flexibility of Individuation

The ability to process concurrently multiple visual objects is fundamental for a coherent perception of the world. A core component of this ability is the simultaneous individuation of multiple objects. Many studies have addressed the mechanism of object individuation but it remains unknown whether the visual system mandatorily individuates all relevant elements in the visual field, or whether object indexing depends on task demands. We used a neural measure of visual selection, the N2pc component, to evaluate the flexibility of multiple object individuation. In three ERP experiments, participants saw a variable number of target elements among homogenous distracters and performed either an enumeration task (Experiment 1) or a detection task, reporting whether at least one (Experiment 2) or a specified number of target elements (Experiment 3) was present. While in the enumeration task the N2pc response increased as a function of the number of targets, no such modulation was found in Experiment 2, indicating that individuation of multiple targets is not mandatory. However, a modulation of the N2pc similar to the enumeration task was visible in Experiment 3, further highlighting that object individuation is a flexible mechanism that binds indexes to object properties and locations as needed for further object processing

Speed has an effect on multiple-object tracking independently of the number of close encounters between targets and distractors

Multiple-object tracking (MOT) studies have shown that tracking ability declines as object speed increases. However, this might be attributed solely to the increased number of times that target and distractor objects usually pass close to each other (“close encounters”) when speed is increased, resulting in more target–distractor confusions. The present study investigates whether speed itself affects MOT ability by using displays in which the number of close encounters is held constant across speeds. Observers viewed several pairs of disks, and each pair rotated about the pair’s midpoint and, also, about the center of the display at varying speeds. Results showed that even with the number of close encounters held constant across speeds, increased speed impairs tracking performance, and the effect of speed is greater when the number of targets to be tracked is large. Moreover, neither the effect of number of distractors nor the effect of target–distractor distance was dependent on speed, when speed was isolated from the typical concomitant increase in close encounters. These results imply that increased speed does not impair tracking solely by increasing close encounters. Rather, they support the view that speed affects MOT capacity by requiring more attentional resources to track at higher speeds

Tagging the world : descrying consciousness in cognitive processes

Although having conscious experiences is a fundamental feature of our everyday life, our understanding of what consciousness is is very limited. According to one of the main conclusions of contemporary philosophy of mind, the qualitative aspect of consciousness seems to resist functionalisation, i.e. it cannot be adequately defined solely in terms of functional or causal roles, which leads to an epistemic gap between phenomenal and scientific knowledge. Phenomenal qualities, then, seem to be, in principle, unexplainable in scientific terms. As a reaction to this pessimistic conclusion it is a major trend in contemporary science of consciousness to turn away from subjective experiences and re-define the subject of investigations in neurological and behavioural terms. This move, however, creates a gap between scientific theories of consciousness, and the original phenomenon, which we are so intimately connected with. The thesis focuses on this gap. It is argued that it is possible to explain features of consciousness in scientific terms. The thesis argues for this claim from two directions. On the one hand, a specific identity theory is formulated connecting phenomenal qualities to certain intermediate level perceptual representations which are unstructured for central processes of the embedding cognitive system. This identity theory is hypothesised on the basis of certain similarities recognised between the phenomenal and the cognitive-representational domains, and then utilised in order to uncover further similarities between these two domains. The identity theory and the further similarities uncovered are then deployed in formulating explanations of the philosophically most important characteristics of the phenomenal domain—i.e. why phenomenal qualities resist functionalisation, and why the epistemic gap occurs. On the other hand, the thesis investigates and criticises existing models of reductive explanation. On the basis of a detailed analysis of how successful scientific explanations proceed a novel account of reductive explanation is proposed, which utilises so-called prior identities. Prior identities are prerequisites rather than outcomes of reductive explanations. They themselves are unexplained but are nevertheless necessary for mapping the features to be explained onto the features the explanation relies on. Prior identities are hypothesised in order to foster the formulation of explanatory claims accounting for target level phenomena in terms of base level processes—and they are justified if they help projecting base level explanations to new territories of the target level. The thesis concludes that the identity theory proposed is a prior identity, and the explanations of features of the phenomenal domain formulated with the aid of this identity are reductive explanations proper. In this sense, the thesis introduces the problem of phenomenal consciousness into scientific discourse, and therefore offers a bridge between the philosophy and the science of consciousness: it offers an approach to conscious experience which, on the one hand, tries to account for the philosophically most important features of consciousness, whereas, on the other hand, does it in a way which smoothly fits into the everyday practice of scientific research

Telephone conversation impairs sustained visual attention via a central bottleneck

Recent research has shown that holding telephone conversations disrupts one's driving ability. We asked whether this effect could be attributed to a visual attention impairment. In Experiment 1, participants conversed on a telephone or listened to a narrative while engaged in multiple object tracking (MOT), a task requiring sustained visual attention. We found that MOT was disrupted in the telephone conversation condition, relative to single-task MOT performance, but that listening to a narrative had no effect. In Experiment 2, we asked which component of conversation might be interfering with MOT performance. We replicated the conversation and single-task conditions of Experiment 1 and added two conditions in which participants heard a sequence of words over a telephone. In the shadowing condition, participants simply repeated each word in the sequence. In the generation condition, participants were asked to generate a new word based on each word in the sequence. Word generation interfered with MOT performance, but shadowing did not. The data indicate that telephone conversation disrupts attention at a central stage, the act of generating verbal stimuli, rather than at a peripheral stage, such as listening or speaking

Temporal estimation with two moving objects: overt and covert pursuit

The current study examined temporal estimation in a prediction motion task where participants were cued to overtly pursue one of two moving objects, which could either arrive first, i.e., shortest [time to contact (TTC)] or second (i.e., longest TTC) after a period of occlusion. Participants were instructed to estimate TTC of the first-arriving object only, thus making it necessary to overtly pursue the cued object while at the same time covertly pursuing the other (non-cued) object. A control (baseline) condition was also included in which participants had to estimate TTC of a single, overtly pursued object. Results showed that participants were able to estimate the arrival order of the two objects with very high accuracy irrespective of whether they had overtly or covertly pursued the first-arriving object. However, compared to the single-object baseline, participants’ temporal estimation of the covert object was impaired when it arrived 500 ms before the overtly pursued object. In terms of eye movements, participants exhibited significantly more switches in gaze location during occlusion from the cued to the non-cued object but only when the latter arrived first. Still, comparison of trials with and without a switch in gaze location when the non-cued object arrived first indicated no advantage for temporal estimation. Taken together, our results indicate that overt pursuit is sufficient but not necessary for accurate temporal estimation. Covert pursuit can enable representation of a moving object’s trajectory and thereby accurate temporal estimation providing the object moves close to the overt attentional focus

Closing the Mind's Eye: Incoming Luminance Signals Disrupt Visual Imagery

Mental imagery has been associated with many cognitive functions, both high and low-level. Despite recent scientific advances, the contextual and environmental conditions that most affect the mechanisms of visual imagery remain unclear. It has been previously shown that the greater the level of background luminance the weaker the effect of imagery on subsequent perception. However, in these experiments it was unclear whether the luminance was affecting imagery generation or storage of a memory trace. Here, we report that background luminance can attenuate both mental imagery generation and imagery storage during an unrelated cognitive task. However, imagery generation was more sensitive to the degree of luminance. In addition, we show that these findings were not due to differential dark adaptation. These results suggest that afferent visual signals can interfere with both the formation and priming-memory effects associated with visual imagery. It follows that background luminance may be a valuable tool for investigating imagery and its role in various cognitive and sensory processes