For some people, this act is impossible; they are unable to "see" anything in their minds. The condition, known as aphantasia, affects about 2 per cent of people but remains largely mysterious. Now there is a glimmer of progress in understanding it, with the discovery that electrically stimulating the brain can alter the strength of our mental imagery. Although it's not yet clear if this will benefit people with aphantasia, it could potentially be used to boost memory, navigational ability and creativity in people who don't have aphantasia – or to turn down mental imagery in those haunted by dark, intrusive thoughts. The first detailed study of aphantasia was published in 2015, but it wasn't clear whether people with aphantasia are unable to form mental images to begin with, or whether the conscious brain is somehow blocking access to them.
I bet when you woke up this morning, even before you opened your eyes, you knew where all of your limbs were. You didn't have to look at, or try moving them, to feel their presence. This is because you have the power of proprioception (it's also sometimes called "kinesthesis"). Because it's a sense, just like hearing and seeing, you can have mental imagery specific to it. That's what motor imagery is--just as visual imagery uses the same brain areas as visual perception, motor imagery tends to use the same brain areas responsible for moving your body.
Determining the extent to which different cognitive modalities (understood here as the set of cognitive processes underlying the elaboration of a stimulus by the brain) rely on overlapping neural representations is a fundamental issue in cognitive neuroscience. In the last decade, the identification of shared activity patterns has been mostly framed as a supervised learning problem. For instance, a classifier is trained to discriminate categories (e.g. faces vs. houses) in modality I (e.g. perception) and tested on the same categories in modality II (e.g. imagery). This type of analysis is often referred to as cross-modal decoding. In this paper we take a different approach and instead formulate the problem of assessing shared patterns across modalities within the framework of statistical hypothesis testing. We propose both an appropriate test statistic and a scheme based on permutation testing to compute the significance of this test while making only minimal distributional assumption. We denote this test cross-modal permutation test (CMPT). We also provide empirical evidence on synthetic datasets that our approach has greater statistical power than the cross-modal decoding method while maintaining low Type I errors (rejecting a true null hypothesis). We compare both approaches on an fMRI dataset with three different cognitive modalities (perception, imagery, visual search). Finally, we show how CMPT can be combined with Searchlight analysis to explore spatial distribution of shared activity patterns.
Reasoning by the usage of mental images has been the subject of much debate in Cognitive Science, especially among the schools of depictive and descriptive imagistic representations. Whether or not reasoning with mental images involves a mechanism or a process different from language based reasoning is an important question. This paper proposes that any theory which aims for a cohesive whole needs to be constrained by neurophysiological data and such data can be obtained by the Clock Drawing Test. The Clock Drawing Test (CDT) is a screening tool for cognitive impairment and can be used as a tool to test resilience of certain factors of visual spatial representations. Thus, it can help to form an empirical case for which factors are prone to debility and which factors are not during the onset and progress of cognitive impairment from a mental representation point of view. This paper presents 50 CDT tests done on patients with cognitive impairment and analyses the results which support the case for a depictive rather than a descriptive theory for imagistic representations. Lastly, this paper proposes that there is some evidence for a more dynamic and distributed nature of representation in the observations which question the above dichotomy and can be partly explained by certain aspects of the connectionist school of thought.
When we spend so much of our time online, we're bound to learn something while clicking and scrolling. Discover something new with Mashable's series I learned it on the internet. On a summer Friday a few years ago, I collapsed on my living room floor in a transformative defeat. I sprawled out in the middle of the carpet, tightly clutched a throw pillow to my face, and squeezed my teary eyes shut before impatiently repeating the words, "BEACH. I said them out loud -- with real feeling -- in hopes that the sheer sounds would trigger my brain to do what I'd just learned it wasn't capable of: creating a mental image. Minutes before taking refuge on the floor I was scrolling through Twitter. My timeline was its usual mess of memes and politics, but a tweet that linked to an experience piece from The Guardian, titled "I can't picture things in my mind" caught my attention. "How sad," I naively thought while clicking to learn what exactly the writer meant. By the time I finished reading the excerpt, however, I could tell this stranger was about to describe my own lifelong experience with mental visualization. The article explained that a number of people go through life with "aphantasia," a term coined by neurologist Adam Zeman in 2015 to describe a lack of visual imagination. When most people try to imagine a beach they likely conjure some sort of picture in their heads, be it fuzzy or crystal clear, of sand, water, and perhaps a lifeguard chair. When I try to imagine a beach, though, I close my eyes and only see darkness. I encounter the same frustrating block when trying to picture anything. My childhood home, the Mashable office, and the face of loved ones I've known all my life are stored somewhere in my brain as memories, but I can't intentionally summon mental pictures of them no matter how hard I try. "Aphantasia is a lack of a mind's eye.