Cerebral akinetopsia

From Psy3242

Definition

Cerebral akinetopsia is a syndrome in which a patient loses specifically the ability to perceive visual motion due to cortical lesions outside the striate cortex. Cerebral akinetopsia is different from cerebral achromatopsia which is the inability to perceive color.

Cases

A woman with akinetopsia, L.M., said that she couldn’t cross a street without traffic lights because she couldn’t judge the speed of oncoming traffic. She could see when a target was constantly changing in position, but could not perceive the movements associated with that position change (she also found moving objects, like a person’s mouth while talking, to be unpleasant to look at). She reported that “First the target is completely at rest. Then it suddenly jumps upwards and downwards (Zihl et. al., 1991, p. 2244 as cited in Carlson).” She could still, however, correctly identify objects and faces.

Another patient, R.A., had the opposite problem after damage to the medial right occipital lobe: R.A. could perceive complex movement, but could not identify form. This shows a dissociation between perception of motion and perception of form from motion.