The effects of target and distractor familiarity on visual search in de novo Parkinson's disease patients: Latent inhibition and novel pop-out

De novo Parkinson's disease (PD) patients identified presence or absence of a unique shape presented with homogeneous distractors. Response time (RT) was examined as a function of prior experience with target and/or distractor assessing latent inhibition (LI; slower RTs to a target that was formerly a distractor against a background of distractors that were formerly targets as compared with a novel target with distractors that were formerly targets) and novel pop-out effects. PD patients were slower than controls in detecting test-phase targets compared with preexposure-phase targets. Female PD patients with right-side motor symptoms had elevated LI compared with female controls and female PD patients with left-side symptoms. Male PD patients with right-side symptoms did not exhibit LI. Results are discussed in terms of the dopamine hypothesis and the reciprocal relationship between PD and schizophrenia.