Latent inhibition deficits in high-schizotypal normals: symptom-specific or anxiety-related?

Latent inhibition (LI) is the phenomenon in which subjects who have repeatedly experienced an irrelevant stimulus perform more poorly on a new learning task with that stimulus than with a novel stimulus, presumably because of a decline in stimulus-specific attention. The present article reviews the literature on LI deficits in high-schizotypal normal subjects and schizophrenic patients. Although LI-deficits have been thought to be specific to these groups, evidence is presented that the effects may be related to the anxiety components of high-schizotypality and related pathologies.

Stress affects the selection of relevant from irrelevant stimuli.

Two experiments were used to examine the effects of stress on latent inhibition (LI; poorer learning with a previously exposed irrelevant stimulus rather than a novel stimulus). In Experiment 1, stress was induced in college students by threatening participants' self-esteem with a difficult number series completion test that was related to intelligence. In Experiment 2, the participants were job seekers who were either informed or not that the LI test was part of the selection process. In both experiments, LI was attenuated in high- as compared with low-stressed participants. The results suggest that stress and/or anxiety impairs the inhibition of irrelevant-preexposed stimuli. Implications for understanding the impaired selective attentional processes in schizophrenia and schizotypy are discussed.

Is the attentional dysfunction in schizotypy related to anxiety?

Two factors, 'anxiety-loaded' (AL) and 'perceptual-disorganization' (PD), emerged in a factor analysis of the Schizotypal Personality Questionnaire (SPQ). Sixty of the 219 participants performed a latent inhibition (LI) task. During the pre-exposure phase, one group was exposed to repeated non-reinforced presentations of an irrelevant stimulus and the other was not pre-exposed. In the subsequent test phase, learning was slower in the pre-exposed group than in the non-pre-exposed group. The LI effect was assessed, separately, as a function of SPQ, trait-anxiety sub-scale (TASS) of the State and Trait Anxiety Inventory (STAI), and AL and PD factors scores. LI was disrupted in participants with either high scores on SPQ, STAI, or the AL factor. A regression analysis indicated that both TASS and SPQ independently accounted for LI disruption in high schizotypals, but that the contribution of TASS was stronger. It was suggested that the anxiety component of schizotypy, more than the perceptual-disorganization (schizophrenia-like) component, accounts for the attentional dysfunction in high schizotypals, and for their greater than normal distraction by irrelevant stimuli.

Are high-schizotypal normal participants distractible or limited in attentional resources? A study of latent inhibition as a function of masking task load and schizotypy level.

Two experiments with normal participants examined the effects of masking and masking task load on latent inhibition (LI, poorer learning for a previously exposed irrelevant stimulus than for a novel stimulus) as a function of level of schizotypality. In Experiment 1, a masking task was needed to produce LI. In Experiment 2, with low load, LI was present in low- but not high-schizotypal participants. In high load, LI was abolished in low-schizotypal participants, but only approached significance in high-schizotypal participants. The data support a distraction- rather than a resource-limitation model of attentional dysfunction in high-schizotypal normal participants. In addition, the data indicate that obtaining LI requires that some attention be initially allocated to the preexposed stimulus and then reduced. Implications of the model for understanding attentional dysfunction in schizophrenia are discussed.