Eye movements precede hand movements in decision-making processes

Research suggests that eye movements may come earlier of hand movements in actions that require a two-step decision-making process.

A research team at the University of British Columbia in Canada has been analyzing whether eye movements are the consequence of decision-making, which comes after the decision is made, or if they reflect making a decision and they occur before the decision is made.

Most people face real-life decisions every day that involve both senses and motor skills. For example, when an animal crosses the road, a driver must decide to avoid hitting it. This sequence of events involves first making the decision to brake the car and then putting the motor skills to work to execute the action. Visually guided decision making in movement tasks; that is to say, how the eyes and body work together is an area of ​​research not yet developed.

At the beginning of the process

To analyze the human response, a series of volunteers with an average age of 19 years participated in a follow-up activity in which an animated ball it moved across a computer screen. The ball was randomly programmed to pass through a box on the screen or pass through the side. The volunteers were instructed to follow the ball with their eyes, decide whether the ball would pass by the side or go through the box, and intercept the crash with the box by touching the screen with the index finger of their dominant hand. If the volunteers thought that the ball would not touch the box, they should not press on the screen. The ball was thrown from several different angles and appeared on the screen for very short periods of time, which ranged from 100 to 300 milliseconds.

"This emphasizes that eye movements can indicate move / not move actions before hand movements are executed."

At the same time as this, the researchers measured the ocular position signals of the volunteers, including speed and acceleration of eye movements, with a video tracking system. Sensors connected to the dominant index finger recorded the position of the finger throughout the test. Eye tracking captured both "soft chase" movements, where the eyes closely follow a moving object, and the quicker, more jerky movements associated with activities such as reading, called saccades. The researchers also looked at the decision precision of interception of the actions, that is, whether or not they moved their hand.

The research team found that "eye movements distinguished the actions of moving / not moving at the beginning of the decision process, before the hand started to move. "The smooth pursuit movements in particular corresponded to the precision of the decision to intercept the ball or not and the timing of the interception." This finding emphasizes that eye movements may indicate actions of moving / not moving before hand movements are executed, "the researchers note in statements collected by Neuroscience News." Because eye movements occur naturally and spontaneously, this may open up new avenues for studying the decision making processes in real-world settings. "