Hand Movements and Visual Attention: A Dance of Separate Rhythms

Summary: A new study sheds light on the intricate relationship between our hand movements and the attention they command.

While it’s well known that hand movements influence how we process visual stimuli, this study reveals the surprising independence between the goal of a hand movement and our self-directed, or ‘endogenous’, attention.

By manipulating hand movements and tracking participants’ brain activity with an electroencephalogram (EEG), the researchers found that visual processing of the future hand location still occurs, even when attention is focused elsewhere, suggesting these processes are distinct.

Key Facts:

  1. The research team from Tohoku University used EEG measurements and a method called steady-state visual evoked potential (SSVEP) to measure the brain’s selective attention during the experiment.
  2. The study discovered that even when top-down attention was oriented far from the future hand location, visual processing for that location still occurred, indicating separate processes.
  3. The findings of this study could help develop systems to maintain appropriate attention states and could enhance learning for complex movements and manipulations.

Source: Tohoku University

Our hands do more than just hold objects. They also facilitate the processing of visual stimuli. When you move your hands, your brain first perceives and interprets sensory information, then it selects the appropriate motor plan before initiating and executing the desired movement.

The successful execution of that task is influenced by numerous things, such as ease, whether external stimuli are present (distractions), and how many times someone has performed that task.

Take, for example, a baseball outfielder catching a ball. They want to make sure that when the ball heads their way, it ends up in their glove (the hand-movement goal).

Once the batter hits the ball and it flies towards the outfielder, they begin to visually perceive and select what course of action is best (hand-movement preparation).

They will then anticipate where they should position their hand and body in relation to the ball to ensure they catch it (future-hand location).

This shows a person's hand.
Researchers have long since pondered whether the hand-movement goal influences endogenous attention. Credit: Neuroscience News

Researchers have long since pondered whether the hand-movement goal influences endogenous attention. Sometimes referred to as top-down attention, endogenous attention acts like our own personal spotlight; we choose where to shine it.

This can be in the form of searching for an object, trying to block out distraction whilst working, or talking in a noisy environment. Elucidating the mechanisms behind hand movements and attention may help develop AI systems that support the learning of complicated movements and manipulations.

Now, a team of researchers at Tohoku University has identified that the hand-movement goal attention acts independently from endogenous attention.

“We conducted two experiments to determine whether hand-movement preparation shifts endogenous attention to the hand-movement goal, or whether it is a separate process that facilitates visual processing,” said Satoshi Shioiri, a researcher at Tohoku University’s Research Institute of Electrical Communication (RIEC), and co-author of the paper.

In the first experiment, researchers isolated the attention of the hand-movement goal from top-down visual attention by having participants move their hands to either the same location as a visual target or a differing location to the visual target based on cues. Participants could not see their hands.

For both cases, there was a control condition where the participants were not asked to move their hand.

The second experiment examined whether the order in cues to the hand-movement goal and the visual target impacted visual performance.

Satoshi and his team employed an electroencephalogram (EEG) to measure the brain activity of participants. They also focused on steady state visual evoked potential (SSVEP).

When a person is exposed to a visual stimulus, such as a flashing light or moving pattern, their brain produces rhythmic electrical activity at the same frequency. SSVEP is the change in EEG signal that occurs, and this helps assess the extent to which our brain selectively attends to or processes visual information, i.e, the spatial window.

“Based on the experiments, we concluded that when top-down attention is oriented to a location far from the future hand location, the visual processing of future hand location still occurs. We also found that this process has a much narrower spatial window than top-down attention, suggesting that the processes are separate,” adds Satoshi.

The research group is hopeful the knowledge from the study can be applied to develop systems that maintain appropriate attention states in different occasions.

About this visual neuroscience and movement research news

Author: Public Relations
Source: Tohoku University
Contact: Public Relations – Tohoku University
Image: The image is credited to Neuroscience News

Original Research: Closed access.
Different mechanisms for visual attention at the hand-movement goal and endogenous visual attention” by Satoshi Shioiri et al. Journal of Cognitive Neuroscience


Different mechanisms for visual attention at the hand-movement goal and endogenous visual attention

Visual perception is closely related to body movements and action, and it is known that processing visual stimuli is facilitated at the hand or at the hand-movement goal. Such facilitation suggests that there may be an attentional process associated with the hands or hand movements.

To investigate the underlying mechanisms of visual attention at a hand-movement goal, we conducted 2 experiments to examine whether attention at the hand-movement goal is a process independent from endogenous attention.

Endogenous attention is attention that is intentionally focused on a location, feature, or object. We controlled the hand-movement goal and endogenous attention separately to investigate the spatial profiles of the two types of attention.

A visual target was presented either at the goal of hand movement (same condition) or at its opposite side (opposite condition) while steady-state visual-evoked potential (SSVEP) was used to estimate the spatial distributions of the facilitation effect from the 2 types of attention around the hand-movement goal and around the visual target through EEG.

We estimated the spatial profile of attentional modulation for the hand-movement goal by taking the difference in SSVEP amplitude between conditions with and without hand movement, thereby obtaining the effect of visual endogenous attention alone.

The results showed a peak at the hand-movement goal, independent of the location of the visual target where participants intentionally focused their attention (endogenous attention). We also found differences in the spatial extent of attentional modulation.

Spatial tuning was narrow around the hand-movement goal (i.e., attentional facilitation only at the goal location) but was broadly tuned around the focus of endogenous attention (i.e., attentional facilitation spreading over adjacent stimulus locations), which was obtained from the condition without hand movement.

These results suggest the existence of 2 separate mechanisms, 1 underlying the attention at the hand-movement goal and another underlying endogenous attention.

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