In previous studies of attentional focus effects, investigators have measured performance outcome. Here, however, the authors used electromyography (EMG) to determine whether difference between external and internal foci would also be manifested at the neuromuscular level. In 2 experiments, participants (N=11, Experiment 1; N=12, Experiment 2) performed biceps curls while focusing on the movements of the curl bar (external focus) or on their arms (internal focus). In Experiment 1, movements were performed faster under external than under internal focus conditions. Also, integrated EMG (iEMG) activity was reduced when performers adopted an external focus. In Experiment 2, movement time was controlled through the use of a metronome, and iEMG activity was again reduced under external focus conditions. Those findings are in line with the constrained action hypothesis (G. Wulf, N. McNevin, & C. H. Shea, 2001), according to which an external focus promotes the use of more automatic control processes.

In cross-dimensional visual search tasks, target discrimination is faster when the previous trial contained a target defined in the same visual dimension as the current trial. The 'dimensionweighting' account (DWA; Found & Müller, 1996) explains this intertrial facilitation by assuming that visual dimensions are weighted at an early perceptual stage of processing. Recently, this view has been challenged by models claiming that intertrial facilitation effects are generated at later stages that follow attentional target selection (Mortier et al., 2005). To determine whether intertrial facilitation is generated at a perceptual stage, at the response selection stage, or both, we focused on specific ERP components (directly linkable to perceptual and response-related processing) during a compound search task. Visual dimension repetitions were mirrored by shorter latencies and enhanced amplitudes of the N2pc suggesting a facilitated allocation of attentional resources to the target. Response repetitions and changes systematically modulated the LRP amplitude suggesting a benefit from residual activations of the previous trial biasing the correct response. Overall, the present findings strengthen the DWA indicating a perceptual origin of dimension change costs in visual search.

BackgroundPostural instability while standing, walking, and interacting with objects or the environment places individuals with Parkinson disease (PD) at risk for falls, injuries, and self-imposed restrictions in activity. Recent research with motor skills, including those demanding postural stability, has demonstrated performance and learning advantages when performers are instructed to adopt an external rather than an internal focus of attention. Despite the potential benefits in stability-related risk reduction and enhanced movement effectiveness, attentional focus research in individuals challenged with postural instability is limited.ObjectiveThe present translational research study examined the generalizability of the attentional focus effect to balance in older adults with PD.DesignA within-participant design was used to account for potentially substantial individual variations in balancing capabilities.MethodsFourteen participants diagnosed with idiopathic PD (Hoehn and Yahr stages II and III) participated in the experiment. They were asked to balance on an unstable surface (inflated rubber disk). In counterbalanced orders, they were instructed to focus on reducing movements of their feet (internal focus) or the disk (external focus), or they were not given attentional focus instructions (control).ResultsThe adoption of an external focus resulted in less postural sway relative to both internal focus and control conditions. There was no difference between the internal focus and control conditions.LimitationsMental functioning was not formally assessed, and comprehensive clinical profiles of participants were not obtained.ConclusionsThe results are consistent with previous findings on attentional focus in samples of patients and people without disabilities. Subtle wording distinctions that direct attention to movement effects external to the mover reduce postural instability during standing for individuals with PD relative to an internal focus. The findings have potentially important implications for instructions given by clinicians and the reduction of fall risk.

The notion of a saliency-based processing architecture [1] underlying human vision is central to a number of current theories of visual selective attention [e.g., 2]. On this view, focal-attention is guided by an overall-saliency map of the scene, which integrates (sums) signals from pre-attentive sensory feature-contrast computations (e.g., for color, motion, etc.). By linking the Posterior Contralateral Negativity (PCN) component to reaction time (RT) performance, we tested one specific prediction of such salience summation models: expedited shifts of focal-attention to targets with low, as compared to high, target-distracter similarity. For two feature-dimensions (color and orientation), we observed decreasing RTs with increasing target saliency. Importantly, this pattern was systematically mirrored by the timing, as well as amplitude, of the PCN. This pattern demonstrates that visual saliency is a key determinant of the time it takes for focal-attention to be engaged onto the target item, even when it is just a feature singleton.

1Sometimes, salient-but-irrelevant objects (distractors) presented concurrently with a search 2 target cannot be ignored and attention is involuntarily allocated towards the distractor first. 3Several studies have provided electrophysiological evidence for involuntary misallocations of 4 attention towards a distractor, but much less is known about the mechanisms that are needed 5 to overcome a misallocation and re-allocate attention towards the concurrently presented 6 target. In our study, electrophysiological markers of attentional mechanisms indicate that (i) 7 the distractor captures attention before the target is attended, (ii) a misallocation of attention is 8 terminated actively (instead of attention fading passively), and (iii) the misallocation of 9 attention towards a distractor delays the attention allocation towards the target (rather than 10 just delaying some post-attentive process involved in response selection). This provides the 11 most complete demonstration, to date, of the chain of attentional mechanisms that are evoked 12 when attention is misguided and recovers from capture within a search display. 13