Aphantasia involves a lack of mental images—but doesn't affect behavior

Some people really cannot imagine. Literally.

There are many people who are astonished to discover that their complete lack of ability to picture visual imagery is different from the norm.

Anhedonia, which means 'without pleasure' in Greek, is typical in major depressive disorder

This common symptom—a flat affect—results in previously enjoyable hobbies no longer bringing pleasure. People with anhedonia may also avoid social situations because they anticipate they'll bring no joy, not because of anxiety or fear.

Always forget a face? The science of face-blindness

Faces and names don't always go together in some people's minds. While everyone forgets other peoples's names occasion, people diagnosed with prosopagnosia can't recognize faces, much less names. Even friends can family members can appear to be strangers. This article covers the diagnosis and issues attendant to prosopagnosia and its sufferers.

Anosmia is the total loss of the sense of smell

This type of loss—due to disease or trauma—has ripple effects, including an altered or limited sense of taste. This video details the anatomy and physiology of our sense of smell and taste and how these senses are interrelated.

Apeirophobia is the fear of everlasting life and may stem from the human brain's inability to conceptualize the concept of anything happening beyond what it can project out, such as the concept of an infinite life.

Photographic memory isn't real, but other rare memory types do exist

While 2% of children can recall sensory experiences with extreme detail (eidetic memory) and some adults can remember life events or dates with high accuracy (hyperthymesia), there is no scientific evidence for the flawless recall popularized in fiction. Most memory feats instead rely on training and memorization techniques.

Roughly 15 of every 1,000 people in the US have smell disorders

Anosmia is a lack of a sense of smell. It can be present at birth, related to diseases including Parkinson's, Alzheimer's, and COVID-19, or have unknown causes.

Individuals with synesthesia experience involuntarily overlapping sensations

Tasting words or seeing colors in music results from the brain retaining extrasensory connections from infancy. While most lose these neural pathways during development, about 4% of people are synesthetes, maintaining them without realizing it's unusual.

Mathematicians often solve problems using wordless mental processes

It's a common technique among expert mathematicians, where thinkers rely on intuition, blurry perceptions and subconscious work—no writing, no formulas. The state is distinct from daydreaming, and often relies on sudden illuminations stemming from extended periods of subconscious reflection.

Apophenia, the cognitive bias that leads people to find meaning in randomness, helps explain why humans look for meaning in their dreams and even in their tea leaves.

Brain conditions and surgery can cause some individuals to feel no fear

Fear is a survival mechanism that originates in the brain's amygdala, triggering the body's fight-or-flight response. However, in modern society, without the same natural dangers, fear can lead to anxiety and mental health issues when unnecessarily triggered. Understanding individuals without fear may help identify new methods to treat anxiety disorders.

People with a sleep disorder called REM Sleep without Atonia don't experience the temporary paralysis of skeletal muscles that typically occurs during REM sleep—instead, they have vivid dreams that they act out during sleep.

How the brain processes a calendar year

When most of us picture a calendar year, we have a foggy image in our minds of the months, in rough, calendar-like grids. But for some folks, that picture is a whole lot more clear. Around 1 percent of the population has a strange ability known as "calendar synaesthesia," which means they're able to visualize in crisp detail an elaborate calendar of the months of the year. Learn how it works here.

Examining self-diagnosed synesthesia

A growing number of people on social media claim to have a perceptual condition that lets them smell colors, see music, or taste sounds. But do they really?

Why 'spacing out' or dissociating may help reduce trauma awareness

Dissociation may have developed as a defense mechanism in the brain to help navigate intense emotional or physical situations by providing out-of-body experiences that put distance between the mind and the environment. However, in about 1.1% and 1.5% percent of the general population, a severe form of this separation can produce alternate identities, or alters.

Humans experience the world subjectively. What does that mean for scientific research?

When you close your eyes, do you see static or colorful patterns or an "intrinsic grey" known as Eigengrau in German? This variation of our internal experiences is just the tip of the iceberg, one that scientists are increasingly studying and...

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Using brain implants to restore vision

Several companies are attempting to create brain-computer interfaces that skip over retinas and optic nerves to allow visual input to go straight to the brain, potentially restoring some sight to the blind. Clinical trial findings suggest restored sight is sparse and manifests differently than a sighted person might expect, appearing as specks of "light" clusters called phosphenes to help differentiate one's surroundings.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

She can't feel pain, hunger, or danger

Olivia Farnsworth, born with a rare chromosome 6p deletion, may be the only person known to lack pain, hunger, and fear responses. This overview explores her unique condition, the incredible incidents that revealed it, and how scientists hope her case could unlock new insights into human survival and sensory systems.

Sleep is no longer considered a binary state—scientists are seeking to map a variety of liminal states between sleep and waking, including the hypnagogic state associated with boosts of creativity.

The dreaming brain, as understood by scientists

Technology has advanced to where the seemingly separate fields of psychology and neuroscience are asking the same questions about dreams, such as whether they're more closely related to perception or visualization. Some field-intersecting findings include research that shows people with impaired face perception don't dream of faces, those with brain legion-related cognition difficulties deal with similar issues in dreams, and children's dreams change in parallel to their cognitive development.

Modern media exposure may impact whether people dream in color or black and white.

Bill Nye did not have children for fear of passing on ataxia

In his 2017 documentary, Nye revealed the congenital, neurological condition on his father's side of the family, which is characterized by a lack of balance and problems with fine motor movement. He has since learned he likely does not have the disease, though both his siblings have shown symptoms.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

Research suggests the brain maintains connections to lost limbs

Decades-old research suggested brain reorganization after amputations, but brain scans show unchanged limb representations. Phantom limb pain may result from such unchanged brain maps, which may enhance prosthetic limb control in brain-computer interface technology.

Dreams largely occur during REM sleep (but not entirely).

Synesthesia: when sensation in one sense triggers an unrelated sense in the brain

The first reported clinical case of synesthesia dates back to the early 1800s, though the perceptual phenomenon may be much older than surviving records imply. This article by researcher Richard Cytowic details the scientific history of synesthesia, a neurological trait that causes some senses to overlap, giving color to numbers and flavors to names.

An intense fear must persist for at least six months to be diagnosed as a phobia.

Narcolepsy occurs when the brain loses its ability to control its sleep-wake cycle.

How dreams affect your memory

In 1999, scientists conducted a study in which participants were asked to recall images flashed before them for milliseconds. They found that participants who slept before recalling the information performed better than those who had been asked to recall the same information that same day. This was some of the earliest convincing evidence of how crucial sleep is for learning and memory, findings that current research continues to strengthen.

Patient H.M. revealed that the hippocampus was responsible for memory formation

Henry Molaison became a landmark case in psychology after surgery removed large portions of his hippocampus, leaving him unable to form new memories. Upon his death, Molaison's brain was sliced into 2,401 sections and digitized for research.

A near-death experience is a phenomenon experienced by roughly 5% to 23% of the population, and typically occurs after a traumatic physical event or a brief clinical death.

Phantom limbs aren't just limited to limbs—there are phantom breasts, teeth, and more, and these sensations are often painful.

What is the brain up to when the mind wanders?

As you stare into the distance while washing your home's seemingly never-ending pile of dishes, the brain activates its default mode network. This collection of "task-negative" brain regions associated with memory, reward, action consideration, and prediction alight with activity when humans mentally turn inward, possibly giving rise to the brain's ability to wander and humans' ability to construct internal narratives about the world.

One theory claims the retinae of SAD patients may fail to adjust to less light in winter

Most people’s eyes become more sensitive to light in the winter months, but some do not. This failure to adjust causes ripple effects on those individuals’ biological clocks. This Ted-ED video provides a clear, brief, narrative explanation of the condition in six minutes.

The unavailability bias says what we don't see must not exist

Before social media, information was more scarce, and it was the norm not to know much about some controversy or episode. This led to a common prejudice: the availability bias, that what is at hand must be true (in business, the courts, finance, and many fields). With information overload today, the inverse occurs: when something is missing (like the photo of a suspect), it makes us think the suspect does not exist.

The depression paradox refers to a lack of energy to take action to help alleviate it

Activities like exercise, even at low levels, have been shown to alleviate some of depression's symptoms for some people. However, depression saps energy levels, making it particularly difficult to motivate oneself to take helpful action.

Why don’t you remember all your dreams?

Despite being a near-nightly occurrence, we remember very few of our dreams. Researchers believe reduced activity in regions where memories are stored, a different neurochemical environment during sleep, and rapid transition during waking contribute to this phenomenon.

Blindfolded people could identify objects by touch alone a week after encountering them

These touch memories are more complex and durable than previously thought. In research published in 2018, blindfolded volunteers touched over 150 household objects for about 10 seconds each, and afterward correctly identified the objects more than 90 percent of the time when presented with the object and a similar one. Participants still knew most of the objects a week later with about 85 percent accuracy. (Some users may experience a paywall.)

Nonamputees can be tricked into thinking they have phantom limbs with rubber arm experiments.

Proteins with limited light sensitivity prevent humans from seeing all types of light

Specialized photoreceptor cells in the retina called cones each possess photopigments that activate when exposed to three ranges of visible light. Other forms of electromagnetic radiation outside the activation range do not generate signals for processing in the brain, thereby limiting average human vision to approximately 10 million colors.

SAD uniquely affects people with attention-deficit hyperactivity disorder

Those with ADHD—chronic issues with attention and executive function—are primed for SAD. Many are disproportionately evening chronotypes (more awake in the evening), have a delayed sleep phase, and have low sensitivity to light in the morning. This podcast explores the overlap between these two groups.

Within an anechoic chamber, all surfaces are covered with specialized materials that prevent wave reflection, helping prevent sound from echoing in the space.

Smell is a robust memory cue for individuals with Alzheimer's disease

Odor is more effective than both visual and verbal cues for triggering autobiographical recall in Alzheimer's disease, according to 2021 research.

Visualizing a synaesthetic soundscape

Artist Michal Levy has chromesthesia, a subtype of synesthesia in which sounds and music trigger involuntary associations with and sensations of color. This condition gives Levy a unique artistic perspective and ability to interact with and interpret music. In this short animation, Levy tries to capture her audiovisual experience of 'Giant Steps," considered a landmark composition in jazz history by musician John Coltrane.

1 in 15 adults over age 40 experience phantom odors

This phenomenon was measured in a 2018 study that examined the prevalence and risk factors for phantom odor perception. Older adults were less likely to experience these phantom odors as they age, just as their overall sense of smell declines. Women are more likely than men to perceive phantom odors.

How people imagine a calendar year

It turns out everybody imagines the abstract calendar year in a simple, concrete way, though there are surprising differences between the exact model and shape of each image. Dive into one writer's collection of tens of thousands of questionnaire responses showing the fascinating consistency and divergence of how people visualize time.

When common sounds become disturbing

Misophonia causes certain sounds to feel violating, triggering a "very visceral kind of experience" filled with extremely unpleasant emotions, including annoyance, anger, and disgust. A 2017 study found that people with misophonia have elevated activity in the brain's anterior insula—a region associated with interoception, emotional processing, and behavioral responses—when exposed to trigger sounds. Ongoing research suggests trigger sound context affects the severity and manifestation of the condition.

SAD 101 from the folks at NIMH—where the condition was first identified

Norman Rosenthal led the team at the National Institute of Mental Health that first identified and described seasonal affective disorder in 1984. This 101 from NIMH explores the basics of the condition, from who develops it to how it is treated.