Some people move through life narrating everything in a running inner monologue; others have no inner voice at all. Some can summon a vivid picture in the mind's eye; others — by some estimates around 1–4% of people — picture nothing whatsoever, a trait called aphantasia. This course is a clear, evidence-based tour of how differently human beings experience their own minds.Across five short videos from TED-Ed, SciShow and leading researchers, you'll explore the two great dimensions of inner experience. The first is inner speech — the voice in your head: where it comes from, why studies suggest 70–85% of us hear one at least some of the time, and what it does for thinking, planning and self-control. The second is mental imagery — the mind's eye: the spectrum running from aphantasia to vivid hyperphantasia, and the clever experiments scientists use to prove the difference is real.You'll learn from Adam Zeman, the neurologist who named aphantasia, and from psychologist Ethan Kross on how to turn the voice in your head from a source of anxious chatter into a tool you can use. By the end you'll be able to place your own inner world on these spectrums and understand why a friend's experience of thinking may be nothing like your own — a richer, kinder map of the most private part of being human.
As your morning alarm blares, you mutter to yourself, “Why did I set it so early?” While brushing your teeth, you think, “I need a haircut... unless?” Rushing out the front door, you reach for your keys and realize they’re not there. Frustrated you shout, “I can’t do anything right!” just in time to notice your neighbor. Being caught talking to yourself can feel embarrassing, and some people even stigmatize this behavior as a sign of mental instability. But decades of psychology research show that talking to yourself is completely normal. In fact, most, if not all, of us engage in some form of self-talk every single day. So why do we talk to ourselves? And does what we say matter? Self-talk refers to the narration inside your head, sometimes called inner speech. It differs from mental imagery or recalling facts and figures. Specifically, psychologists define self-talk as verbalized thoughts directed toward yourself or some facet of your life. This includes personal conversations like “I need to work on my free throw.” But it also includes reflections you have throughout the day, like “The gym is crowded tonight. I’ll come back tomorrow.” And while most self-talk in adults tends to be silent, speaking to yourself out loud also falls into this category. In fact, psychologists believe our first experiences with self-talk are mostly vocal, as children often speak to themselves out loud as they play. In the 1930s, Russian psychologist Lev Vygotsky hypothesized that this kind of speech was actually key to development. By repeating conversations they’ve had with adults, children practice managing their behaviors and emotions on their own. Then, as they grow older, this outward self-talk tends to become internalized, morphing into a private inner dialogue. We know this internal self-talk is important, and can help you plan, work through difficult situations, and even motivate you throughout the day. But studying self-talk can be difficult. It relies on study subjects clearly tracking a behavior that’s spontaneous and often done without conscious control. For this reason, scientists are still working to answer basic questions, like, why do some people self-talk more than others? What areas of the brain are activated during self-talk? And how does this activation differ from normal conversation? One thing we know for certain, however, is that what you say in these conversations can have real impacts on your attitude and performance. Engaging in self-talk that’s instructional or motivational has been shown to increase focus, boost self-esteem, and help tackle everyday tasks. For example, one study of collegiate tennis players found that incorporating instructional self-talk into practice increased their concentration and accuracy. And just as chatting to a friend can help decrease stress, speaking directly to yourself may also help you regulate your emotions. Distanced self-talk is when you talk to yourself, as if in conversation with another person. So, rather than “I’m going to crush this exam,” you might think, “Caleb, you are prepared for this test!” One study found that this kind of self-talk was especially beneficial for reducing stress when engaging in anxiety-inducing tasks, such as meeting new people or public speaking. But where positive self-talk can help you, negative self-talk can harm you. Most people are critical of themselves occasionally, but when this behavior gets too frequent or excessively negative, it can become toxic. High levels of negative self-talk are often predictive of anxiety in children and adults. And those who constantly blame themselves for their problems and ruminate on those situations typically experience more intense feelings of depression. Today, there’s a field of psychological treatment called cognitive behavioral therapy, or CBT, which is partially focused on regulating the tone of self-talk. Cognitive behavioral therapists often teach strategies to identify cycles of negative thoughts and replace them with neutral or more compassionate reflections. Over time, these tools can improve one's mental health. So the next time you find yourself chatting with yourself, remember to be kind. That inner voice is a partner you’ll be talking to for many years to come.
When reading Lewis Carroll’s “Alice’s Adventures in Wonderland,” most readers visualize the Queen's croquet game play out in their heads. “...it was all ridges and furrows; the balls were live hedgehogs, the mallets live flamingos, and the soldiers had to double themselves up and to stand on their hands and feet, to make the arches.” A few might see vivid details, such as the pattern of the hedgehog's quills or the flush of the queen's face. However, a small fraction of readers have a drastically different experience. As the scene plays out on the page, within their heads, they “see” absolutely nothing. This inability to clearly visualize images in the mind’s eye is known as aphantasia, and it applies to around 4% of the world’s population. It was first characterized by a psychologist in the 19th century, who asked study participants to visualize their breakfast table and then rate the vividness and color of this mental picture. He determined that mental imagery exists on a spectrum. At one end are people with aphantasia, and at the other are people with hyperphantasia, with imagery so real, it rivals seeing. And most people land somewhere in between these two extremes. But how do we know if someone with aphantasia isn’t describing the same experience as someone with mental imagery, just in different terms? In other words, how does one objectively measure what’s going on in someone else’s mind? In one study, scientists looked for clues in people's eyes. They investigated differences in pupillary light reflexes, or how the pupil automatically constricts in response to light. Even just imagining that you are looking into a light will cause the pupil to narrow— or at least it will if you have mental imagery. They found that the eyes of people with aphantasia don’t constrict when imagining light. Brain-imaging studies may help decipher another perplexing phenomenon: people with aphantasia can see mental imagery when they dream. How this happens is likely explained by the contrasting ways the brain generates deliberate visualization versus dream imagery. Typically, conjuring a mental image involves multiple brain regions, and is sometimes referred to as a top-down process. First, actively trying to visualize an object activates cognitive control regions of our brain. This then drives activity in regions of the brain associated with memory and vision, creating a mental picture. People with hyperphantasia tend to have stronger connections between these regions compared to those with aphantasia. As for dreaming, many scientists believe this imagery is produced by a different bottom-up pathway, through activity deep in the brain spontaneously activating visual and memory systems. So, what causes the spectrum of mental imagery to develop? Aphantasia often runs in families, suggesting that the vividness of your mental canvas may be influenced by your genes. While most people with aphantasia have it their entire lives, some people can develop it later in life— often due to brain injury or psychological conditions. But in most cases, imagery extremes aren’t considered disorders in need of treatment, but rather intriguing variations in human experience. For example, for those with a mind's eye, the excitement of a thrilling story will cause them to sweat a little, even if they don't notice it. People with aphantasia, however, lack this sweat response— presumably because it depends on the emotional effect of imagining the the storyline. At the same time, scientists have speculated that aphantasia may be protective against certain mental health disorders, specifically those related to negative imagery, like PTSD— though more research is needed. Recalling details, like the food served at last year’s holiday party, may not be as difficult for people with hyperphantasia, as they tend to have a richer memory of past events and can “relive” these experiences in greater detail. Differences in mental imagery may even influence your career choice. A survey of over 2,000 people found that those with aphantasia are more likely to work in STEM professions, while people with hyperphantasia tend to gravitate towards jobs in the arts, media, and design. We may never be able to fully understand what’s happening in another person's mind. The inner worlds of those around you might be quite different from your own.