I remember a case where someone apparently had great difficulty perceiving the distance of an object if it was (quickly) travelling towards them. Their depth perception was otherwise fine, but when, for instance, catching a ball, that person could not accurately gauge depth and seemed to rely on guesswork/other cues (size of the object? timing?) to decide when to attempt to catch it. Hand-eye coordination was not a problem, and for slow-moving objects (for instance, rolling a ball across the floor) there was no problem. What is the name of this condition, and what could be likely causes?

2 Answers 2


Dysmetria is a possibility. (Specifically Ocular Dysmetria)

It is a type of ataxia characterised:

is a lack of coordination of movement typified by the undershoot or overshoot of intended position

It can occur in the major skeletal muscles and the eyes.

Ocular Dysmetria:

During eye movements hypometric and hypermetric saccades will occur [...]

Saccades are the very quick, simultaneous movements made by the eye to receive visual information and shift the line of vision from one position to another. A person depends profoundly on the ability of the accuracy of these movements. The information is received from the retina, is translated into spatial information and is then transferred to motor centers for motor response.

As you might imagine, when tracking a moving object, the person's spacial sense is likely to be recieving garbled input and will not function as well as when an object is stationary.


Lesions in the cerebellum or in the proprioceptive nerves that lead to the cerebellum that coordinate visual, spatial and other sensory information with motor control.

Damage to the proprioceptive nerves does not allow the cerebellum to accurately judge where the hand, arm, leg, or eye should move.

Causes of the lesions are manfold; stroke, tumour, ALS, or MS.

I am unable to find treatments specific to the Ocular version, but treatment regimes with clonazepam or a tailored form of Frenkel exercises - both of which seem to be of benefit to general Dysmetria patients - may come into play.


What you appear to be describing is called Akinetopsia.

(Greek: a for "without", kine for "to move" and opsia for "seeing")

a neuropsychological disorder in which a patient cannot perceive motion in their visual field, despite being able to see stationary objects without issue [...]
There are varying degrees of akinetopsia: from seeing motion as a cinema reel to an inability to discriminate any motion. There is currently no effective treatment or cure for akinetopsia.

Causes range from brain lesions to dementia, certain medications such as antidepressants (nefazodone) and halucinogens such as LSD. It may be induced artificially by Transcranial magnetic stimulation.

  • That doesn't sound like it. This person was able to perceive motion, just not depth. They could see the ball moving, but were unable to gauge its distance while it was moving at some speed towards them.
    – Bas
    Commented Mar 14, 2019 at 13:58
  • @Bas Do you remember the context at all? I'd be happy to do some more research, maybe make another answer. Just noticed a spelling mistake in this one, will edit. Commented Mar 14, 2019 at 14:01
  • I only remember that it was research for remedial education at a high school. The student was roughly 15 years old, and had some underdeveloped motor skills ("clumsy" and "bad at sports", not necessarily anything severe) and this was grounds for using the student as research into remedial teaching. Granted, this was roughly 20 years ago, and I don't know anything about remedial teaching, so I have no idea how outdated this all is. One of the conclusions was a problem with depth perception when it comes to fast-moving objects.
    – Bas
    Commented Mar 14, 2019 at 15:37
  • I don't remember if it was only when they were travelling towards the student, or if they also had difficulties gauging depth with lateral moving objects, although I suppose that would be hard to determine.
    – Bas
    Commented Mar 14, 2019 at 15:37

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