Correct! In order to get the correct answer here, you must be aware that pursuit is mediated by a pathway that starts in the parietal lobe and generates pursuit eye movements ipsilaterally. When you move the optokinetic drum, you generate an obligatory pursuit movement in the direction of the moving stripes (the patient must be paying attention!). Each pursuit movement is met by an oppositely-directed conjugate saccadic movement that restores the eye position to straight ahead. You can use this device to generate repetitive jerk nystagmus. If you consistently see a discrepancy in nystagmus amplitude between rightwardly and leftwardly directed stripes, you must conclude that there is a unidirectional pursuit deficit caused by a lesion in the ipsilateral parietal lobe. By the way, the patient will not notice this pursuit deficit.