Learning to trust our senses

为了有效地与环境互动，我们必须估计我们所感知到的东西的可靠性或精确度。例如，如果我们在一个漆黑的夜晚在公园里寻找我们的狗，我们可能对视觉信号的精确度缺乏信心，因此依赖其他感官(例如，听觉)或部署其他策略来获取更多信息。这种对我们感官信心的在线评估依赖于大脑中的元认知监控机制，这种机制被认为受到语境信息的影响(Deroy，Spence&Noppeney，2016；Pereira等人，2020)。虽然许多科学家认为我们确实会产生这种“关于精确度的信念”，但目前还不清楚是否是这样，以及我们感官的自信是如何在大脑中编码的。上了年纪的成年人往往会根据感官信号做出更糟糕的决定，初步证据表明，知觉元认知能力也会随着年龄的增长而下降，这增加了一种可能性，即糟糕的决定可能是我们对感官精确度的不准确信念造成的。建立知觉元认知的基本认知和神经机制有望理解次优的信念和行为，特别是在老年人中看到的那些。这个博士项目将使用多种方法来描述支撑我们感觉可靠性的元水平信念的认知和神经机制，并将研究这些机制如何随着我们的年龄变化。首先，我们将检验这样一个假设，即观察者形成关于知觉的元水平信念，并且这些信念偏向于知觉自信。通过使用经典的动作连贯任务(Britten，Shadlen，Newome和Movhson，1992)和最先进的知觉和元认知绩效的心理物理测量(Maniscalco&Lau，2012)，我们将测试对信号强度的预期是否会偏离知觉自信(例如，当观察者预期强烈的信号时，他们是否倾向于对他们的选择更有信心？)。然后，我们将测试这种信心偏差是否会转化为行为的战略变化，例如，如果参与者对他们的决定没有信心，他们会寻求更多信息来改善他们的选择吗？在研究了这些基本机制之后，我们将使用脑电(EEG)来记录大脑的电活动，应用最先进的多变量模式解码技术来确定信号强度是如何在大脑中编码的，以及这些表示是如何由关于信号强度的元认知信念塑造的。参与者将在记录大脑活动的同时完成相同的任务。首先，分析将确定客观信号强度是否编码在主要的视觉区域或与决策信心有关的“较高”大脑区域。一旦确定了这些区域，我们就会问模式强度是否会被自上而下的预期所改变，并将利用脑电出色的时间分辨率来询问是否甚至在刺激出现之前就出现了预测性偏差。然后，经颅磁刺激(TMS)实验将使用非侵入性脑刺激来测试这些脑区在前面实验中发现的效果的因果贡献。最后，我们将在这些研究中开发的机制框架的基础上，通过对广泛年龄段的样本来探索元水平信念如何在一生中发生变化。这将确定这些机制在健康老龄化中发生的任何变化，加深我们对我们如何随着年龄的增长监控和依赖我们的感官，以及关于感官的信念可能会出现错误的理解。了解这些与年龄相关的知觉元认知和自我意识的变化对心理学家来说很重要，并对更广泛的社会科学和公共政策具有重要意义。

To effectively interact with the environment we must estimate the reliability or precision of what we can perceive. For example, if we are looking for our dog in the park on a dark night, we may have low confidence in the precision of visual signals and therefore rely on other senses (e.g., hearing) or deploy other strategies to gain more information. This online assessment of confidence in our senses depends on metacognitive monitoring mechanisms in the brain which are thought to be influenced by contextual information (Deroy, Spence, & Noppeney, 2016; Pereira et al., 2020). While many scientists assume we do generate these kinds of 'beliefs about precision', it remains unclear whether this is the case and how confidence in our senses is encoded in the brain. Ageing adults tend to make poorer decisions based on sensory signals and preliminary evidence suggests that perceptual metacognition also declines with age This raises the possibility that poor decision-making could be explained by our inaccurate beliefs about the precision of our senses. Establishing the fundamental cognitive and neural mechanisms of perceptual metacognition holds promise for understanding suboptimal beliefs and behaviour, especially those seen in older adults.This PhD project will use a multi-method approach to characterise the cognitive and neural mechanisms that underpin meta-level beliefs about the reliability of our senses and will investigate how these mechanisms change as we age. Firstly, we will test the hypothesis that observers form meta-level beliefs about perception, and that these beliefs bias perceptual confidence. By using a classic motion coherence task (Britten, Shadlen, Newsome, & Movhson, 1992) and state-of-the art psychophysical measures of perceptual and metacognitive performance (Maniscalco & Lau, 2012), we will test whether expectations about signal strength bias perceptual confidence (e.g., are observers biased to be more confident in their choices when they expect strong signals?). We will then test whether such biases in confidence translate to strategic changes in behaviour e.g., if participants are not confident in their decision will they seek more information to improve their choice? After investigating these fundamental mechanisms, we will use electroencephalography (EEG) to record electrical brain activity, applying state-of-the-art multivariate pattern decoding techniques to establish how signal strength is encoded in the brain and how these representations are shaped by metacognitive beliefs about signal strength. Participants will complete the same task while brain activity is recorded. First, analyses will establish whether objective signal strength is encoded in primary visual areas or 'higher' brain regions implicated in decision confidence. Once these regions are identified, we will ask whether pattern strength is altered by top-down expectations and will use the excellent temporal resolution of EEG to ask whether predictive biases emerge even before stimuli are presented. Transcranial magnetic stimulation (TMS) experiments will then use non-invasive brain stimulation to test the causal contribution of these brain areas in the effects found in the preceding experiments.Finally, we will build on the mechanistic framework developed in these studies to explore how meta-level beliefs change across the lifespan by sampling a wide range of ages. This will identify any changes in these mechanisms that occur in healthy ageing, developing our understanding of how we monitor and rely on our senses as we age and how beliefs about the senses may go awry. Understanding these age-linked changes in perceptual metacognition and self-awareness is important for psychologists and has significant implications for the wider social sciences and public policy.