Enhanced Memory Ability: Insights from Synaesthesia

想想我们研究中一位通感参与者的话：“我的彩色字母和数字对我来说是极好的记忆辅助和提醒。电话号码和日期，如生日和周年纪念，不仅是由美丽的颜色组合组成的，它们还可以有形状……时间单位对我来说也是可见的；有时它们是三维的，在外观上是彩色的或有纹理的……这个系统帮助我计划我的一年。”通感是感知世界的一种非凡方式。对一些人来说，比如上面提到的那个人，字母、数字和单词可能有颜色(字素-颜色通感)，而序列，如年和月，被‘视为’空间中的三维图形(时空通感)。我们已经证明，通感在家族中存在，并在很小的时候就存在。这些体验是诱发的(即由特定刺激触发的)、自动的(即不由自主地发生的)，并且经常被报道具有感知的性质。对于那些有通感的人来说，这是完全正常的：也就是说，不可能想象拥有无色数字是什么感觉。然而，在正式测试中，通感受试者对优势和劣势有着不同寻常的认知特征。在这个研究计划中，我们将研究通感增强的记忆。我们的一般方法是将通感作为一个“测试案例”来解决其他重要的研究问题。例如，我们考虑通感如何为记忆的一般理论提供依据。重要的是，并不是记忆的所有方面都会在通感中得到增强，这可以让我们对记忆系统的结构有更深入的了解。事实上，引起“额外”感觉的材料更容易被记住，这并不是一件微不足道的事情：一些不能引起额外感觉的材料(如抽象图形)也更容易被联觉者记住。我们认为，联觉者的知觉系统有广泛的变化(包括但不限于他们的额外经验)，支持知觉的系统也可以参与记忆。这种方法接触到了当代更广泛的关于记忆的文献，包括那些源自动物模型和健忘症患者的论点。原则上，对卓越能力的研究可以和对能力受损的研究一样，为记忆模型提供信息，尽管后者占主导地位。此外，认知心理学作为一门学科，历来倾向于忽视而不是接受个体差异(在数据中将其归类为“噪音”)。因此，我们试图从一个新的角度来解决与记忆有关的重要问题。从我们对通感的研究中得出的对记忆功能个体差异的理解，将对其他领域产生重大影响。例如，一种说法是，一般而言，增强的功能可能对衰老的病理或认知能力下降具有保护作用。我们将测试通感是否是防止与年龄相关的记忆衰退的保护因素。另一种说法是，我们假设的那种“低水平”或“形象化”的认知方式会在通感中产生增强的记忆，这可能支持其他特殊人群的记忆增强(例如，学者的记忆能力，比如有时在自闭症中发现的记忆能力)。虽然我们没有在我们的主要提案中直接测试这一点，但我们的发现将与该领域的工作人员相关，并将在关联的博士学位中进行探索。为了解决这些问题，我们借鉴了认知心理学/神经科学的广泛方法。我们使用标准和定制的记忆测试来探索记忆的哪些方面得到了增强。我们探索个体在感知上的差异(在非联觉中)如何与某些记忆任务的表现有关。最后，我们使用神经成像和非侵入性脑刺激方法探索大脑如何支持通感中增强的记忆。

Consider the following quote from a synaesthete participant in our studies:"My coloured letters and numbers are for me wonderful memory aids and reminders. Not only are telephone numbers and dates, such as birthdays and anniversaries, made up of beautiful combinations of colours, they can also have shapes.... Units of time are visible to me too; sometimes they are three-dimensional, coloured or textured in appearance... This system helps me to plan my year". Synaesthesia is a remarkable way of perceiving the world. For some people, such as the person quoted above, letters, numbers and words may have colour (grapheme-colour synaesthesia) and sequences, such as years and months, are 'seen' as a three-dimensional figure in space (time-space synaesthesia). We have shown that synaesthesia runs in families and is present from a young age. The experiences are elicited (i.e. triggered by particular stimuli), automatic (i.e. occur involuntarily), and are often reported to have qualities of perceiving. To those who have synaesthesia it feels perfectly normal: that is, it is impossible to imagine what it is like to have, say, colourless numbers. On formal testing, however, synaesthetes have an unusual cognitive profile of strengths and weaknesses. In this research programme we will investigate enhanced memory in synaesthesia.Our general approach is to treat synaesthesia as a 'test case' to address other important research questions. For instance we consider how synaesthesia can inform general theories of memory. Importantly, not all aspects of memory are enhanced in synaesthesia and this can provide insights into how the memory system is structured. Indeed it is not trivially the case that material that elicits 'extra' sensations are better remembered: some material that does not evoke extra sensations (such as abstract figures) are also better remembered by synaesthetes. We suggest that synaesthetes have widespread changes in their perceptual systems (including but not limited to their extra experiences) and that systems supporting perception can also be engaged in memory. This approach makes contact with a much wider contemporary literature on memory including those arguments derived from animal models and patients with amnesia. In principle, studies of superior ability can be just as informative to models of memory as studies of impaired ability, even though the latter approach predominates. Moreover, cognitive psychology as a discipline has historically tended to dismiss rather than embrace individual difference (classifying it as 'noise' in the data). As such, we seek to tackle important questions relating to memory from a novel angle. An understanding of individual differences in memory functioning, derived from our research on synaesthesia, will have significant impact on other areas. For instance, one claim is that enhanced functioning in general may be protective against pathology or cognitive decline in ageing. We will test whether synaesthesia is a protective factor against age-related memory decline. Another claim is that the kind of 'low level' or 'visualising' cognitive style that we hypothesise to give rise to enhanced memory in synaesthesia may support enhanced memory in other special populations (e.g. savant memory abilities such as those sometimes found in autism). Although we do not test this directly in our main proposal, our findings will be relevant to those working in this domain and will be explored in a linked PhD.To tackle these questions we draw on a wide range of methods in cognitive psychology/neuroscience. We use both standard and bespoke tests of memory to explore which aspects of memory are enhanced. We explore how individual differences in perception (in non-synaesthetes) may relate to performance on certain memory tasks. Finally, we explore how the brain supports enhanced memory in synaesthesia using neuroimaging and non-invasive brain stimulation methods