Selectively reduced contrast sensitivity in high schizotypy

Working memory and sensory memory in subclinical high schizotypy: An avenue for understanding schizophrenia?

The search for robust, reliable biomarkers of schizophrenia remains a high priority in psychiatry. Biomarkers are valuable because they can reveal the underlying mechanisms of symptoms and monitor treatment progress and may predict future risk of developing schizophrenia. Despite the existence of various promising biomarkers that relate to symptoms across the schizophrenia spectrum, and despite published recommendations encouraging multivariate metrics, they are rarely investigated simultaneously within the same individuals. In those with schizophrenia, the magnitude of purported biomarkers is complicated by comorbid diagnoses, medications and other treatments. Here, we argue three points. First, we reiterate the importance of assessing multiple biomarkers simultaneously. Second, we argue that investigating biomarkers in those with schizophrenia-related traits (schizotypy) in the general population can accelerate progress in understanding the mechanisms of schizophrenia. We focus on biomarkers of sensory and working memory in schizophrenia and their smaller effects in individuals with nonclinical schizotypy. Third, we note irregularities across research domains leading to the current situation in which there is a preponderance of data on auditory sensory memory and visual working memory, but markedly less in visual (iconic) memory and auditory working memory, particularly when focusing on schizotypy where data are either scarce or inconsistent. Together, this review highlights opportunities for researchers without access to clinical populations to address gaps in knowledge. We conclude by highlighting the theory that early sensory memory deficits contribute negatively to working memory and vice versa. This presents a mechanistic perspective where biomarkers may interact with one another and impact schizophrenia-related symptoms.

Flexible control as surrogate reward or dynamic reward maximization

The utility of a given experience, like interacting with a particular friend or tasting a particular food, fluctuates continually according to homeostatic and hedonic principles. Consequently, to maximize reward, an individual must be able to escape or attain outcomes as preferences change, by switching between actions. Recent work on human and artificial intelligence has defined such flexible instrumental control in information theoretic terms and postulated that it may serve as a reward surrogate. Another possibility, however, is that the adaptability afforded by flexible control is tacitly implemented by planning for dynamic changes in outcome values. In the current study, an expected utility model that computes decision values over a range of possible monetary gains and losses associated with sensory outcomes provided the best fit to behavioral choice data and performed best in terms of earned rewards. Moreover, consistent with previous work on perceived control and personality, individual differences in dimensional schizotypy were correlated with behavioral choice preferences in conditions with the greatest and lowest levels of flexible control. These results contribute to a growing literature on the role of instrumental control in goal-directed choice.