John M. Foley

Visually directed action

publication date
May 2021
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When people throw or walk to targets in front of them without visual feedback, they often respond short. With feedback, responses rapidly become approximately accurate. To understand this, an experiment is performed with four stages. 1) The errors in blind walking and blind throwing are measured in a virtual environment in light and dark cue conditions. 2) Error feedback is introduced and the resulting learning measured. 3) Transfer to the other response is then measured. 4) Finally, responses to the perceived distances of the targets are measured. There is large initial under-responding. Feedback rapidly makes responses almost accurate. Throw training transfers completely to walking. Walk training produces a small effect on throwing. Under instructions to respond to perceived distances, under-responding recurs. The phenomena are well described by a model in which the relation between target distance and response distance is determined by a sequence of a perceptual, a cognitive, and a motor transform. Walk learning is primarily motor; throw learning is cognitive.


This study confirms that in a dark or lighted virtual environment, subjects walk and throw short of the target. It shows that, if they are given error feedback, subjects quickly correct the trained response to be near the target distance on average. Transfer tests show that throw training acts to produce near accurate throwing and walking. Walk training produces near accurate walking and improves throwing slightly. When, after the training and transfer test, subjects are instructed to respond to the perceived positions, some throw-trained subjects revert to their initial stage 1 responses and some show no reversion. Overall, walk-trained subjects show partial reversion, consistent with partial nulling the cognitive transform, but not the walk transform. Within a stage, responses are stable, except for stage 2, in which responses change rapidly in the first session. The results are accounted for by models in which different sets of a perceptual, a cognitive, and a motor transform are applied to determine the response functions in each condition. The effect of error feedback is to change one or both of these transforms.


  • Vision therapy is well worth the response, time and effort. Our Son had a hard time focusing and writing neatly. After vision therapy Seth could complete a task in half the time if previously took. His abilities to focus improved greatly and so did his handwriting.

    Also, he was better at listening. As a parent, we wanted learning to be fun for our Son, and vision therapy made this possible.

    Amanda T.

  • Vision Therapy is well worth the expense, time and effort. Our son had a hard time focusing handwriting neatly. After vision therapy Seth could complete a task in half the time it previously took his abilities to focus and improved greatly and so did his handwriting.

    Also, he was better at listening. As a parent you wanted learning to be fun for our son and vision therapy made this possible.

    Alexa H.

  • Vision Therapy has given or son the tools he needs to be able to scan and read the written word more effectively and efficiently.

    He love working with John and these working sessions give him the motivation to gladly work on his homework assignments.

    It amazed us to see the difference in the tracking of his eyes and along a line of it's from the beginning to the end of the treatment.

    Dr. McBryar , Kristen and John  are all marvelous and we would recommend them to anyone I only wish that we would have found them sooner!

    Charlotte M.

  • Prior to coming to the institute for vision development my son complained of daily headaches. Therapy has eliminated his headaches completely. I love knowing my son is able to learn pain-free for the rest of his life because of the work that has been done over just a few weeks in this office. He he absolutely loved coming that didn't even feel like going to a doctor or therapy. We are grateful for the relief he was able to find by coming here.

    Thank you!

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  • Seems much less frustrated with life

    Reads non-stop and fast

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