Attention
Attention changes perceived size of moving visual patterns.
Spatial attention shifts receptive fields in monkey extrastriate visual cortex toward the focus of attention. This distortion in the retinotopic distribution of receptive fields might cause distortions in spatial perception such as an increase of the perceived size of attended stimuli. Here we test for such an effect in human subjects by measuring the point of subjective equality (PSE) for the perceived size of a neutral and an attended stimulus when drawing automatic attention to one of two spatial locations. We found a significant increase in perceived size of attended stimuli. Depending on the absolute stimulus size, this effect ranged from 4% to 12% and was more pronounced for smaller than for larger stimuli.
In our experimental design, an attentional effect on task difficulty or a cue bias might influence the PSE measure. We performed control experiments and indeed found such effects, but they could only account for part of the observed results. Our findings demonstrate that the allocation of transient spatial attention onto a visual stimulus increases its perceived size and additionally biases subjects to select this stimulus for a perceptual judgment.
(S. Ben Hamed, J. R. Duhamel, F. Bremmer, & W. Graf, 2002; C. E. Connor, J. L. Gallant, D. C. Preddie, & D. C. Van Essen, 1996; C. E. Connor, D. C. Preddie, J. L. Gallant, & D. C. Van Essen, 1997; T. Womelsdorf, K. Anton-Erxleben, F. Pieper, & S. Treue, 2006).
https://www.ncbi.nlm.nih.gov/pubmed/17997660
Audiofeedback
Externally focused instructions have been associated with a range of mechanisms, purported to demonstrate the use of automatic and less attentionally demanding control processes to produce movements more efficiently. These include: reduced probe reaction times during a dynamic balance task (Wulf et al., 2001a); increased accuracy and reduced electromyographic (EMG) activity during basketball free-throw shooting (Zachry et al., 2005) and dart throwing (Lohse et al., 2010a); and higher frequency movement characteristics during balance (e.g., Wulf et al., 2000, 2001b; McNevin et al., 2003). An external focus has also been shown to result in lower EMG activity compared to internal focus and control conditions using force generation tasks (e.g., Vance et al., 2004; Marchant et al., 2008, 2009), which will be discussed later. Collectively, these findings are indicative of reflexive automatic control processes when an external focus is adopted. Importantly, the observed mechanisms suggest that accuracy or outputs are improved in line with more efficient movements when attention is directed to an intended outcome. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153816/
Results revealed higher activation in primary somatosensory and motor cortex for an external compared to an internal focus. The authors conclude that external participants focused on the task-related environment (i.e., the keys) to enhance tactile input to somatosensory areas that closely connect to motor areas. https://www.ncbi.nlm.nih.gov/pubmed/19567364
Both groups received verbal instructions with an external focus on either movement dynamics (movement form) or movement effects (e.g. ball trajectory relative to basket). The participants also observed a skilled model performing the task on either a small or large screen monitor, to ascertain the effects of visual presentation mode on task performance.The results support the benefits of instructions when observing a model with an external focus on movement effects, not dynamics.
https://www.ncbi.nlm.nih.gov/pubmed/11999481/
Increased movement accuracy and reduced EMG activity as the result of adopting an external focus of attention.
The increased movement accuracy and reduced EMG activity as the result of adopting an external focus of attention. he performance and learning of motor skills has been shown to be enhanced if the performer adopts an external focus of attention (focus on the movement effect) compared to an internal focus (focus on the movements themselves) [G. Wulf, W. Prinz, Directing attention to movement effects enhances learning: a review, Psychon. Bull. Rev. 8 (2001) 648-660]. While most previous studies examining attentional focus effects have exclusively used performance outcome (e.g., accuracy) measures, in the present study electromyography (EMG) was used to determine neuromuscular correlates of external versus internal focus differences in movement outcome. Participants performed basketball free throws under both internal focus (wrist motion) and external focus (basket) conditions. EMG activity was recorded for m. flexor carpi radialis, m. biceps brachii, m. triceps triceps brachii, and m. deltoid of each participant's shooting arm. The results showed that free throw accuracy was greater when participants adopted an external compared to an internal focus. In addition, EMG activity of the biceps and triceps muscles was lower with an external relative to an internal focus. This suggests that an external focus of attention enhances movement economy, and presumably reduces "noise" in the motor system that hampers fine movement control and makes the outcome of the movement less reliable.
