Schizotypy and Perceptual Learning: Aberrant Salience or Disrupted Inhibition?

精神分裂症是一种复杂的、异质性的诊断类别，其特征是幻觉、拥有不寻常的信仰和混乱的认知和行为。在整个人群中，症状是连续变化的，一个人表现出特征的程度可以用“分裂型”的测量来检验。潜在抑制（LI）是指与未预暴露的条件刺激相比，在没有非条件刺激的情况下，先前暴露于条件刺激（CS）会损害随后对CS和US之间关系的学习。当代的学习模型表明，在预暴露期间，对CS的注意力会下降，因为参与者知道刺激并不意味着重大事件。LI在被诊断为精神分裂症的个体中被破坏，并且与分裂型特征呈负相关。Lubow（2005）认为，LI的作用是将注意力引向相关刺激，远离无关刺激。这些研究表明，高度分裂型的个体分配注意力的效率较低，对不相关的刺激保持更多的注意力。有一种假设认为，幻觉是由于对内部刺激的异常突出分配而产生的，当一个人试图理解这些经历时，就会产生错觉。虽然这些理论对精神分裂症的阳性症状提供了全面的解释，但它们忽视了阴性症状。然而，Kapur（2005）的理论可以扩展到解释抑郁症状（DS），一种常见的阴性症状。开创性的研究表明，缺乏调节环境偶然事件的能力是抑郁症的一个因果作用；我们可以将其概念化为环境结果（US）和个人行为（CS）之间的关联。至关重要的是，这种情况发生的背景也与美国形成了联系，因此，CS-US关系与背景-US关系在行为控制方面处于竞争地位。由于上下文信息是冗余的，它的显著性应该下降。然而，如果非预测性刺激在高分裂型个体中获得更大的显著性，那么背景的显著性将保持更长时间。由于显著性是学习的核心，在高度分裂型个体中，情境-美国关联会相对较强，而cs -美国关联会相对较弱，最终导致退行性痴呆。“知觉学习”指的是预先接触刺激有助于随后对刺激进行区分的现象。McLaren等人（1989）通过提出刺激包括许多元素来解释这一点，这些元素由每个刺激所独有的元素和两个刺激所共有的元素组成。预暴露于两种刺激（如CS-A和CS-B）会导致共同元素的LI相对高于独特元素。因此，对CS-A的了解不太容易推广到CS-B，从而促进了歧视。此外，CS-A的独特元素成为CS-B独特元素的条件抑制剂。作者认为，由于同时呈现，共同元素与两种刺激的独特元素独立关联。因此，CS-A在缺乏CS-B的独特元素的情况下呈现会出现预测误差，导致独特元素的条件抑制。尽管有证据表明知觉学习依赖于LI和条件抑制，这两种现象在高分裂型个体中被破坏，但知觉学习在高分裂型个体中是否异常仍有待研究。本研究将研究分裂型对知觉学习的影响，并阐明是否有任何异常可归因于LI和/或抑制关联的中断。此外，本研究旨在阐明DS是否与LI或抑制性关联的发展有关

Schizophrenia is a complex, heterogenous diagnostic category characterised by hallucinations, the possession of unusual beliefs and disorganised cognitions and behaviours. Symptoms vary on a continuum throughout the population and the extent to which one displays traits can be examined with measures of 'schizotypy'. Latent inhibition (LI) refers to the phenomenon that prior exposure to a conditioned stimulus (CS) in the absence of an unconditioned stimulus (US) impairs subsequent learning about the relationship between the CS and US, compared to a CS that has not been pre-exposed. Contemporary models of learning suggest that attention to the CS declines during pre-exposure, as participants learn that the stimulus does not signal a significant event. LI is disrupted in individuals with a diagnosis of schizophrenia and is inversely related to schizotypal traits. Lubow (2005) suggested that LI serves to direct attention towards relevant stimuli and away from irrelevant stimuli. These studies indicate that individuals with high schizotypy allocate attention less efficiently, maintaining greater attention towards irrelevant stimuli. It has been postulated that hallucinations occur consequential to the aberrant assignment of salience to internal stimuli and that delusions arise when one attempts to understand these experiences.Whilst these theories provide a comprehensive account of the positive symptoms of schizophrenia, they neglect the negative symptoms. However, Kapur's (2005) theory can be extended to account for depressive symptomology (DS), a common negative symptom. Seminal research indicated that the perceived absence of the ability to modulate environmental contingencies entails a causal role in depression; one can conceptualise this as an association between an environmental outcome (US) and one's actions (CS). Crucially, the context in which this occurs also develops an association with the US, such that the CS-US relationship is in competition with the context-US relationship for behavioural control. As contextual information is redundant, its salience should decline. However, if non-predictive stimuli acquire greater salience in individuals with high schizotypy, the context's salience will remain higher for longer. As salience is central to learning, the context-US association will be relatively stronger and the CS-US association will be relatively weaker in individuals with high schizotypy, culminating in DS.'Perceptual learning' refers to the phenomenon that pre-exposure to stimuli aids subsequent discrimination between the stimuli. McLaren et al (1989) explained this by suggesting that stimuli comprise a number of elements, composed of those that are unique to each stimulus and those that are common to both stimuli. Pre-exposure to both stimuli (e.g. CS-A and CS-B) results in relatively greater LI of the common elements than the unique elements. Accordingly, learning about CS-A generalises less readily to CS-B, facilitating discrimination. Moreover, the unique elements of CS-A become conditioned inhibitors of the unique elements of CS-B. The authors suggested that the common elements become independently associated with the unique elements of both stimuli, due to concurrent presentation. Therefore, presentation of CS-A in the absence of the unique elements of CS-B manifests a prediction error, resulting in conditioned inhibition of the unique elements. Despite evidence that perceptual learning is dependent upon both LI and conditioned inhibition, phenomena which are disrupted in individuals with high schizotypy, it remains to be examined whether perceptual learning is abnormal in individuals with high schizotypy. This research will examine the influence of schizotypy on perceptual learning and elucidate whether any abnormality is attributable to disrupted LI and/or disrupted inhibitory associations. Moreover, this study aims to elucidate whether DS is related to either LI or the development of inhibitory associa