Action-feature integration blinds to feature-overlapping perceptual events: evidence from manual and vocal actions

Previous studies showed that the identification of a left- or right-pointing arrowhead is impaired when it appears while planning and executing a spatially compatible left or right keypress (Müsseler & Hommel, 1997a). We attribute this effect to stimulus processing and action control operating on the same feature codes so that, once a code is integrated in an action plan, it is less available for perceptual processing. In three pairs of experiments we tested the generality of this account by using stimulus-response combinations other than arrows and manual keypresses. Planning manual left-right keypressing actions impaired the identification of spatially corresponding arrows but not of words with congruent meaning. On the contrary, planning to say "left" or "right" impaired the identification of corresponding spatial words but not of congruent arrows. Thus, as the feature-integration approach suggests, stimulus identification is impaired only with overlap of perceptual or perceptually derived stimulus and response features while mere semantic congruence is insufficient.     

Target integration and the attentional blink

If people monitor a visual stimulus stream for targets they often miss the second (T2) if it appears soon after the first (T1)--the attentional blink. There is one exception: T2 is often not missed if it appears right after T1, i.e., at lag 1. This lag-1 sparing is commonly attributed to the possibility that T1 processing opens an attentional gate, which may be so sluggish that an early T2 can slip in before it closes. We investigated why the gate may close and exclude further stimuli from processing. We compared a control approach, which assumes that gate closing is exogenously triggered by the appearance of nontargets, and an integration approach, which assumes that gate closing is under endogenous control. As predicted by the latter but not the former, T2 performance and target reversals were strongly affected by the temporal distance between T1 and T2, whereas the presence or the absence of a nontarget intervening between T1 and T2 had little impact.     

Event files: feature binding in and across perception and action

The primate brain codes perceived events in a distributed fashion, which raises the question of how the codes referring to the same event are related to each other. Recent findings suggest that they are integrated into 'object files', episodic bindings of object-related information. However, the problem of integrating distributed codes is not restricted to perception but applies to action planning and sensorimotor processing as well. Here I argue that the brain addresses these problems by creating multi-layered networks of bindings - 'event files' - that temporarily link codes of perceptual events, the current task context, and the actions performed therein. These bindings produce systematic but often surprising and counter-intuitive interactions between, and impairments in, perception and action planning.     

Dynamics, Brandom-style

This paper discusses the semantic theory presented in Robert Brandom’s Making It Explicit. I argue that it is best understood as a special version of dynamic semantics, so that these semantics by themselves offer an interesting theoretical alternative to more standard truth-conditional theories. This reorientation also has implications for more foundational issues. I argue that it gives us the resources for a renewed argument for the normativity of meaning. The paper ends by critically assessing the view in both its development and motivations.     

Attentional scanning in the selection of central targets from multi-symbol strings

Abstract

Subjects responded to five-symbol strings consisting of a central target, one or two compatible or incompatible flankers, and neutral symbols in the remaining positions. Performance strongly depended on the position of compatible or incompatible flankers. With normal letters, left-side flankers had a much larger impact than right-side flankers. This left-side asymmetry of the flanker compatibility effect disappeared with strings composed of spaced letters or of tiny pictures and tended to turn into a right-side asymmetry with vertically mirrored letters. These results seem to indicate the operation of attentional scanning processes. Flankers may be scanned either automatically, due to a reading-like habit, or strategically, in attempting to localize the target.     

The topography of training-induced visual field recovery: Perimetric maps and subjective representations

The cognitive representation of blind regions varies considerably between patients with vision loss and may influence compensatory behaviour and treatment motivation. We therefore measured “objective” visual field topography (perimetry) in 19 patients with postgeniculate visual system lesions and related this to the subjective scotoma representation as expressed by patients’ drawings of the defect and monitored changes of these measures during training-induced recovery of function. Blind regions were mostly adequately represented; however, central regions were overestimated and peripheral areas underestimated in size. Perimetric and subjective defect size decreased significantly during training. Again, training-induced visual field border shifts in central regions were larger in subjective than in perimetric maps but vice versa in the peripheral field. Thus, vision restoration therapy improves “objective” visual field size along with its cognitive representation. The subjective topography is shaped by the functional importance of visual field regions and is a function of cortical magnification, thus resembling the neural representation in visual cortex.     

Visual attention and the temporal dynamics of feature integration

Two experiments studied the emergence of bindings between stimulus features (object files) and between stimulus and response features (event files) over time. Choice responses (R2) were signalled by the shape of a stimulus (S2) that followed another stimulus (S1) of the same or different shape, location, and colour. S1 did not require a response (Experiment 1) or trigger a precued simple response (R1) that was or was not repeated by R2 (Experiment 2). Results demonstrate that the mere cooccurrence of stimulus features, and of stimuli and responses, is sufficient to bind their codes. Bindings emerge quickly and remain intact for at least four seconds. Which features are considered depends on their task‐relevance; hence, integration reflects the current attentional set. There was no consistent trend toward higher order interactions as a function of time or of the amount of attention devoted to S1, suggesting that features are not integrated into a single, global superstructure, but enter independent local bindings presumably subserving different functions.     

Visual attention and manual response selection: Distinct mechanisms operating on the same codes

In four experiments, participants made a speeded manual response to a tone and concurrently selected a cued visual target from a masked display for later unspeeded report. In contrast toaprevious study of H.Pashler (1991), systematic interactions between the two tasks were obtained. First, accuracy in both tasks decreased with decreasing stimulus (tone-display)-onset asynchrony (SOA)— presumably due to a conflict between stimulus and response coding. Second, spatial correspondence between manual response and visual target produced better performance in the visual task and, with short SOAs, in the tone task, too— presumably due to the overlap of the spatial codes used by stimulus- and response-selection processes. Third, manual responding slowed down with increasing SOA — reflecting either a functional bottleneck or strategic queuing of target selection and response selection. Results suggest that visual stimulus selection and manual response selection are distinct mechanisms that operate on common representations.     

Critical Notices

Abstract

I argue that a practice can only be taken to be one of apparent rule following if it contains a practice of policing moves within the practice. So the existence of an apparently rule‐governed practice entails the existence of, what I call, a policing practice. I then argue that this entailment cannot be reconciled with a non‐factualist construal of the policing practice. Thus non‐factualism about the policing practice is false. Factualism about the policing practice entails realism about rules. So I conclude that we ought to be realists about rules. Finally I distinguish a position which I call ultra‐realism about rules and note that this too is a casualty of the view developed here.