Hiatus and Announcement

It has been a month and a half since I last posted. For those of you who might have wondered, I didn’t die and I haven’t been kidnapped. I’ve been preparing to move to Boston for a new job. In early July, I will start as the new editor of Trends in Cognitive Sciences at Cell Press. I’m excited to take the helm of a journal that I have loved reading for many years.

Of course, editors aren’t known for having loads of free time and I don’t expect to be able to blog frequently once my new job begins. I hope to make occasional posts and I certainly hope you will visit me here, on Twitter, and soon in the pages of TiCS. Thank you for reading and please stay in touch!

Zapping Brains, Seeing Scenes

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More than fifteen years ago, neuroimagers found a region of the brain that seemed to be all about place. The region lies on the bottom surface of the temporal lobe near a fold called the parahippocampal gyrus, so it was called the parahippocampal place area, or PPA. You have two PPAs: one on the left side of your brain and one on the right. If you look at a picture of a house, an outdoor or indoor scene, or even an empty room, your PPAs will take notice. Since its discovery, hundreds of experiments have probed the place predilections of the PPA. Each time, the region demonstrated its dogged devotion to place. Less clear was exactly what type of scene information the PPA was representing and what it was doing with that information. A recent scientific paper now gives us a rare, direct glimpse at the inner workings of the PPA through the experience of a young man whose right PPA was stimulated with electrodes.

The young man in question wasn’t an overzealous grad student. He was a patient with severe epilepsy who was at the hospital to undergo brain surgery. When medications can’t bring a person’s seizures under control, surgery is one of few remaining option. The surgery involves removing the portion of the brain in which that patient’s seizures begin. Of course, removing brain tissue is not something one does lightly. Before a surgery, doctors use various techniques to determine in each patient where the seizures originate and also where crucial regions involved in language and movement are located. They do this so they will know which part of the brain to remove and which parts they must be sure not to remove. One of the ways of mapping these areas before surgery is to open the patient’s skull, plant electrodes into his or her brain, and monitor brain activity at the various electrode sites. This technique, called electrocorticography, allows doctors to both record brain activity and electrically stimulate the brain to map key areas. It is also the most powerful and direct look scientists can get into the human brain.

A group of researchers in New York headed by Ashesh Mehta and Pierre Mégevand documented the responses of the young man as they stimulated electrodes that were planted in and around his right PPA. During one stimulation, he described seeing a train station from the neighborhood where he lives. During another, he reported seeing a staircase and a closet stuffed with something blue. When they repeated the stimulation, he saw the same random indoor scene again. So stimulating the PPA can cause hallucinations of scenes that are both indoor and outdoor, familiar or unfamiliar. This suggests that specific scene representations in the brain may be both highly localized and complex. It is also just incredibly cool.

The doctor also stimulated an area involved in face processing and found that this made the patient see distortions in a face. Another study published in 2012 showed a similar effect in a different patient. While the patient looked at his doctor, the doctor stimulated the face area. As the patient reported, “You just turned into somebody else. Your face metamorphosed.” Here’s a link to a great video of that patient’s entire reaction and description.

The authors of the new study also stimulated a nearby region that had shown a complex response to both faces and scenes is previous testing. When they zapped this area, the patient saw something that made him chuckle. “I’m sorry. . . You all looked Italian. . . Like you were working in a pizza shop. That’s what I saw, aprons and whatnot. Yeah, almost like you were working in a pizzeria.”

Now wouldn’t we all love to know what that area does?

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Photo credit: thisisbossi on Flickr, used via Creative Commons license

*In case you’re wondering, the patient underwent surgery and no longer suffers from seizures (although he still experiences auras).

Mégevand P, Groppe DM, Goldfinger MS, Hwang ST, Kingsley PB, Davidesco I, & Mehta AD (2014). Seeing scenes: topographic visual hallucinations evoked by direct electrical stimulation of the parahippocampal place area. The Journal of neuroscience : the official journal of the Society for Neuroscience, 34 (16), 5399-405 PMID: 24741031

What Do Preschoolers Learn from Fantastical Picture Books?

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One of the new picture books making the bedtime rounds at our house is How Do Dinosaurs Say Goodnight?, which describes and depicts dinosaurs doing such un-dinosaurly things as tucking themselves into bed or kissing their human mothers good night. The book is whimsical, gorgeously illustrated, and includes a scientific angle, as the genus names of the dinosaurs are included in the pictures. I’m always careful to read these genus names aloud as we look at each picture. But is this book actually teaching my daughter anything about dinosaurs? And does the misinformation get in the way of her learning these facts? A new study suggests that it might.

Picture books that anthropomorphize animals – and even inanimate objects – are the norm rather than the exception. These books are whimsical and fanciful. They depict worlds like our own but different in magical ways that delight children and adults alike. Perhaps these books are more engaging for young children, fostering lifelong reading habits. Perhaps they stimulate a child’s blossoming imagination. Perhaps – although I would argue that the true story of our diverse, teeming planet is more remarkable than talking teddy bears or hippos in swimsuits.

Look at it this way: everything we do is meant to prepare our children for life in this complex and befuddling world. Why, then, do we feed them so much distorted, inaccurate information? How are they supposed to know what is real and what is fantasy? How is my daughter supposed to know that the three-horned dinosaur was called Triceratops but that it never coexisted with humans nor stomped on its hind legs to protest bedtime?

Researchers in Boston and Toronto looked into this issue and recently published their findings in Frontiers in Psychology. The scientists created picture books based on three animals species that are relatively unknown among North American children: cavies, oxpeckers, and handfish. Their study consisted of two separate experiments. For the first experiment, all of the books featured factual illustrations of the animals, but for each animal the authors made one version of the book with realistic text and one version with text that depicted the animals as human-like. Here are two examples:

Lonely cavy seeks companionship and good conversation.

Lonely cavy seeks companionship and good conversation.

Realistic
When the mother cavy wakes up, she usually eats lots of grass and other plants.
Then the mother cavy feeds her baby cavies.
Mother cavy also licks the babies’ fur to keep them clean.
Mother cavy and her babies spend the rest of the day lying in the sun.
At night, they sleep in a small cave.
After they go to sleep, mother cavy’s big ears help her hear noises around her.

Anthropomorphic
“Yum, those grass and plants are delicious!” Mother cavy thinks as she eats her breakfast.
“I will feed some to my baby cavies too!” she says.
The baby cavies love to play in the grass! But they’ve gotten all dirty! “Time for your bath,” Mother cavy says.
Mother cavy and her babies like to spend the afternoon sunbathing.
At night, Mother cavy tucks her babies in to bed in a small cave. “Mom, I’m scared!” says the baby cavy.
“Don’t be afraid,” she says. “I’ll listen for noises with my big ears and keep us safe.”

Children ages 3 to 5 years old were randomly assigned to read the books with either the factual or fantasy text. After children read one of these books with an experimenter, a second experimenter showed them a picture of the real animal described the story and asked the kids questions about it. Do cavies eat grass? Do cavies talk? Some of these questions tested the factual information kids took away from the picture book, while others tested how much the children anthropomorphized the animal. The children who read the books with talking animals were more likely to say those animals really talk than were children who read the versions with factual text. Still, the two groups were roughly equal in the factual information they retained about the animals.

Oxpeckers ready for adventure.

Oxpeckers ready for adventure.

For the second experiment, the researchers again made two versions of picture books for each animal. This time, both versions showed the animals dressed in clothes, sitting at tables, or engaged in other human activities. As before, the researchers made two versions of each book: one with factual text and one that anthropomorphized the animals. The children who read the fully anthropomorphized picture books tended to believe that the animals really engage in human behaviors like speech. These kids also answered fewer factual questions about the animals correctly (compared with the children who read factual text paired with the fantastical pictures).

These findings have two major implications. First, picture books that anthropomorphize animals seem to actually teach children that animals think and behave like humans. In one sense you might say this is good, as it could discourage animal cruelty and abuse. But in another sense, it’s highly unproductive. At the very best, children will have to unlearn all of this nonsense. At worst, they will carry some of this misinformation about the natural world throughout life – probably not as a belief in talking animals, but in the assumptions they make about the thoughts, feelings, and intentions of other species.

The other takeaway is that the whimsical aspects of a picture book may be sabotaging your child’s learning of the real information in these stories, particularly when the illustrations and text both reflect fantasy.  Since children can’t conclusively tell fact from fiction, some may be discounting all information from highly fanciful stories – including incredible-yet-true facts like the chameleon’s mercurial skin tone or the transformation of caterpillar into butterfly. As the authors write in their paper: “if the goal of the picture book interaction is to teach children information about the world, it is best to use books that depict the world in a realistic rather than fantastical manner.” Of course that takes enthusiasm out of the equation. What kid would sit for hours watching videos of real trains when he or she could watch Thomas? Human narrative adds interest, but it also seems to muddle up real learning, at least in preschoolers.

I hate to build an argument against imaginative, fanciful picture books. What am I, Scrooge? But while I love imagination, I don’t love misinformation – particularly scientific misinformation. And while I love magic, I don’t love magical thinking or flawed reasoning about the natural world. I’m not saying you should throw away your copy of Goodnight Moon and all things Sandra Boynton – just keep in mind that wee ones don’t always know real from fanciful or facetious. Talk about these concepts with them. Buy some nonfiction picture books with accurate information about animals and keep them in the lineup. And know that, for all your efforts, they may come away believing that trains talk and bunnies knit . . . at least for now.

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Photo credits:  Mother and child by KatLevPhoto, cropped for use here; cavy by Brent Moore; oxpeckers by Steve Garvie. All used via Creative Commons license

Ganea, P., Canfield, C., Simons Ghafari, K., & Chou, T. (2014). Do cavies talk? The effect of anthropomorphic picture books on children’s knowledge about animals Frontiers in Psychology, 5 DOI: 10.3389/fpsyg.2014.00283

Did I Do That? Distinguishing Real from Imagined Actions

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If you’re like most people, you spend a great deal of your time remembering past events and planning or imagining events that may happen in the future. While these activities have their uses, they also make it terribly hard to keep track of what you have and haven’t actually seen, heard, or done. Distinguishing between memories of real experiences and memories of imagined or dreamt experiences is called reality monitoring and it’s something we do (or struggle to do) all of the time.

Why is reality monitoring a challenge? To illustrate, let’s say you’re at the Louvre standing before the Mona Lisa. As you look at the painting, visual areas of your brain are busy representing the image with specific patterns of activity. So far, so good. But problems emerge if we rewind to a time before you saw the Mona Lisa at the Louvre. Let’s say you were about to head over to the museum and you imagined the special moment when you would gaze upon Da Vinci’s masterwork. When you imagined seeing the picture, you were activating the same visual areas of the brain in a similar pattern to when you would look at the masterpiece itself.*

When you finally return home from Paris and try to remember that magical moment at the Louvre, how will you be able to distinguish your memories of seeing the Mona Lisa from imagining her? Reality monitoring studies have asked this very question (minus the Mona Lisa). Their findings suggest that you’ll probably use additional details associated with the memory to ferret out the mnemonic wheat from the chaff. You might use memory of perceptual details, like how the lights reflected off the brushstrokes, or you might use details of what you thought or felt, like your surprise at the painting’s actual size. Studies find that people activate both visual areas (like the fusiform gyrus) and self-monitoring regions of the brain (like the medial prefrontal cortex) when they are deciding whether they saw or just imagined seeing a picture.

It’s important to know what you did and didn’t see, but another crucial and arguably more important facet of reality monitoring involves determining what you did and didn’t do. How do you distinguish memories of things you’ve actually done from those you’ve planned to do or imagined doing? You have to do this every day and it isn’t a trivial task. Perhaps you’ve left the house and headed to work, only to wonder en route if you’d locked the door. Even if you thought you did, it can be hard to tell whether you remember actually doing it or just thinking about doing it. The distinction has consequences. Going home and checking could make you late for work, but leaving your door unlocked all day could mean losing your possessions. So how do we tell the possibilities apart?

Valerie Brandt, Jon Simons, and colleagues at the University of Cambridge looked into this question and published their findings last month in the journal Cognitive, Affective, and Behavioral Neuroscience. For the first part of the experiment (the study phase), they sat healthy adult participants down in front of two giant boxes – one red and one blue – that each contained 80 ordinary objects. The experimenter would draw each object out of one of the two boxes, place it in front of the participant, and tell him or her to either perform or to imagine performing a logical action with the object. For example, when the object was a book, participants were told to either open or imagine opening it.

After the study phase, the experiment moved to a scanner for fMRI. During these scans, participants were shown photographs of all 160 of the studied objects and, for each item, were asked to indicate either 1) whether they had performed or merely imagined performing an action on that object, or 2) which box the object had been drawn from.** When the scans were over, the participants saw the pictures of the objects again and were asked to rate how much specific detail they’d recalled about encountering each object and how hard it had been to bring that particular memory to mind.

The scientists compared fMRI measures of brain activation during the reality-monitoring task (Did I use or imagine using that object?) with activation during the location task (Which box did this object come from?). One of the areas they found to be more active during reality monitoring was the supplementary motor area, a region involved in planning and executing movements of the body. Just as visual areas are activated for reality monitoring of visual memories, motor areas are activated when people evaluate their action memories. In other words, when you ask yourself whether you locked the door or just imagined it, you may be using details of motor aspects of the memory (e.g., pronating your wrist to turn the key in the lock) to make your decision.

The study’s authors also found greater activation in the anterior medial prefrontal cortex when they compared reality monitoring for actions participants performed with those they only imagined performing. The medial prefrontal cortex encompasses a respectable swath of the brain with a variety of functions that appear to include making self-referential judgments, or evaluating how you feel or think about experiences, sensations, and the like. Other experiments have implicated a role for this or nearby areas in reality monitoring of visual memories. The study by Brandt and Simons also found that activation of this medial prefrontal region during reality-monitoring trials correlated with the number of internal details the participants said they’d recalled in those trials. In other words, the more details participants remembered about their thoughts and feelings during the past actions, the busier this area appeared to be. So when faced with uncertainty about a past action, the medial prefrontal cortex may be piping up about the internal details of the memory. I must have locked the door because I remember simultaneously wondering when my package would arrive from Amazon, or, because I was also feeling sad about leaving my dog alone at home.

As I read these results, I found myself thinking about the topic of my prior post on OCD. Pathological checking is a common and often disruptive symptom of the illness. Although it may seem like a failure of reality monitoring, several behavioral studies have shown that people with OCD have normal reality monitoring for past actions. The difference is that people with checking symptoms of OCD have much lower confidence in the quality of their memories than others. It seems to be this distrust of their own memories, along with relentless anxiety, that drives them to double-check over and over again.

So the next time you find yourself wondering whether you actually locked the door, cut yourself some slack. Reality monitoring ain’t easy. All you can do is trust your brain not to lead you astray. Make a call and stick with it. You’re better off being wrong than being anxious about it – that is, unless you have really nice stuff.

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Photo credit: Liz (documentarist on Flickr), used via Creative Commons license

* Of course, the mental image you conjure of the painting is actually based on the memory of having seen it in ads, books, or posters before. In fact, a growing area of neuroscience research focuses on how imagining the future relies on the same brain areas involved in remembering the past. Imagination seems to be, in large part, a collage of old memories cut and pasted together to make something new.

**The study also had a baseline condition, used additional contrasts, and found additional activations that I didn’t mention for the sake of brevity. Check out the original article for full details.

Brandt, V., Bergström, Z., Buda, M., Henson, R., & Simons, J. (2014). Did I turn off the gas? Reality monitoring of everyday actions Cognitive, Affective, & Behavioral Neuroscience, 14 (1), 209-219 DOI: 10.3758/s13415-013-0189-z

The Slippery Question of Control in OCD

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It’s nice to believe that you have control over your environment and your fate – that is until something bad happens that you’d rather not be responsible for. In today’s complex and interconnected world, it can be hard to figure out who or what causes various events to happen and to what degree you had a hand in shaping their outcomes. Yet in order to function, everyone has to create mental representations of causation and control. What happens when I press this button? Did my glib comment upset my friends? If I belch on the first date, will it scare her off?

People often believe they have more control over outcomes (particularly positive outcomes) than they actually do. Psychologists discovered this illusion of control in controlled experiments, but you can witness the same principle in many a living room now that March Madness is upon us. Of course, wearing your lucky underwear or sitting in your go-to La-Z-Boy isn’t going to help your team win the game, and the very idea that it might shows how easily one’s sense of personal control can become inflated. Decades ago, researchers discovered that the illusion of control is not universal. People suffering from depression tend not to fall for this illusion. That fact, along with similar findings from depression, gave rise to the term depressive realism. Two recent studies now suggest that patients with obsessive-compulsive disorder (OCD) may also represent contingency and estimate personal control differently from the norm.

OCD is something of a paradox when it comes to the concept of control. The illness has two characteristic features: obsessions based on fears or regrets that occupy a sufferer’s thoughts and make him or her anxious, and compulsions, or repetitive and unnecessary actions that may or may not relieve the anxiety. For decades, psychiatrists and psychologists have theorized that control lies at the heart of this cycle. Here’s how the NIMH website on OCD describes it (emphasis is mine):

The frequent upsetting thoughts are called obsessions. To try to control them, a person will feel an overwhelming urge to repeat certain rituals or behaviors called compulsions. People with OCD can’t control these obsessions and compulsions. Most of the time, the rituals end up controlling them.

In short, their obsessions cause them distress and they perform compulsions in an effort to regain some sense of control over their thoughts, fears, and anxieties. Yet in some cases, compulsions (like sports fans’ superstitions) seem to indicate an inflated sense of personal control. Based on this conventional model of OCD, you might predict that people with the illness will either underestimate or overestimate their personal control over events. So which did the studies find? In a word: both.

The latest study, which appeared this month in Frontiers in Psychology, used a classic experimental design to study the illusion of control. The authors tested 26 people with OCD and 26 comparison subjects. The subjects were shown an image of an unlit light bulb and told that their goal was to illuminate the light bulb as often as possible. On each trial, they could choose to either press or not press the space bar. After they made their decision, the light bulb either did or did not light up. Their job was to estimate, based on their trial-by-trial experimentation, how much control they had over the light bulb. Here’s the catch: the subjects had absolutely no control over the light bulb, which lit up or remained dark according to a fixed sequence.*

After 40 trials, subjects were asked to rate the degree of control they thought they had over the illumination of the light bulb, ranging from 0 (no control) to 100 (complete control). Estimates of control were consistently higher for the comparison subjects than for the subjects with OCD. In other words, the people with OCD believed they had less control – and since they actually had no control, that means that they were also more accurate than the comparison subjects. As the paper points out, this is a limitation of the study: it can’t tell us whether patients are generally prone to underestimating their control over events or if they’re simply more accurate that comparison subjects. To do that, it would need to have included situations in which subjects actually did have some degree of control over the outcomes.

Why wasn’t the light bulb study designed to distinguish between these alternatives? Because the authors were expecting the opposite result. They had designed their experiment to follow up on a 2008 study that found a heightened illusion of control among people with OCD. The earlier study used a different test. They showed subjects either neutral pictures of household items or disturbing pictures of distorted faces. The experimenters encouraged the subjects to try to control the presentation of images by pressing buttons on a keyboard and asked them to estimate their control over the images three times during the session. However, just like in the light bulb study, the presentation of the images was fixed in advance and could not be affected by the subjects’ button presses.

How can two studies of estimated control in OCD have opposite results? It seems that the devil is in the details. Prior studies with tasks like these have shown that healthy subjects’ control estimates depend on details like the frequency of the preferred outcome and whether the experimenter is physically in the room during testing.  Mental illness throws additional uncertainty into the mix. For example, the disturbing face images in the 2008 study might have made the subjects with OCD anxious, which could have triggered a different cognitive pattern. Still, both findings suggest that control estimation is abnormal for people with OCD, possibly in complex and situation-dependent ways.

These and other studies indicate that decision-making and representations of causality in OCD are altered in interesting and important ways. A better understanding of these differences could help us understand the illness and, in the process, might even shed light on the minor rituals and superstitions that are common to us all. Sadly, like a lucky pair of underwear, it probably won’t help your team get to the Final Four.

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Photo by Olga Reznik on Flickr, used via Creative Commons license

*The experiment also manipulated reinforcement (how often the light bulb lit up) and valence (whether the lit bulb earned them money or the unlit bulb cost them money) across different testing sections, but I don’t go into that here because the manipulations didn’t affect the results.

Gillan CM, Morein-Zamir S, Durieux AM, Fineberg NA, Sahakian BJ, & Robbins TW (2014). Obsessive-compulsive disorder patients have a reduced sense of control on the illusion of control task. Frontiers in Psychology, 5 PMID: 24659974

In the Blink of an Eye

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It takes around 150 milliseconds (or about one sixth of a second) to blink your eyes. In other words, not long. That’s why you say something happened “in the blink of an eye” when an event passed so quickly that you were barely aware of it. Yet a new study shows that humans can process pictures at speeds that make an eye blink seem like a screening of Titanic. Even more, these results challenge a popular theory about how the brain creates your conscious experience of what you see.

To start, imagine your eyes and brain as a flight of stairs. I know, I know, but hear me out. Each step represents a stage in visual processing. At the bottom of the stairs you have the parts of the visual system that deal with the spots of darkness and light that make up whatever you’re looking at (let’s say an old family photograph). As you stare at the photograph, information about light and dark starts out at the bottom of the stairs in what neuroscientists called “low-level” visual areas like the retinas in your eyes and a swath of tissue tucked away at the very back of your brain called primary visual cortex, or V1.

Now imagine that the information about the photograph begins to climb our metaphorical neural staircase. Each time the information reaches a new step (a.k.a. visual brain area) it is transformed in ways that discard the details of light and dark and replace them with meaningful information about the picture. At one step, say, an area of your brain detects a face in the photograph. Higher up the flight, other areas might identify the face as your great-aunt Betsy’s, discern that her expression is sad, or note that she is gazing off to her right. By the time we reach the top of the stairs, the image is, in essence, a concept with personal significance. After it first strikes your eyes, it only takes visual information 100-150 milliseconds to climb to the top of the stairs, yet in that time your brain has translated a pattern of light and dark into meaning.

For many years, neuroscientists and psychologists believed that vision was essentially a sprint up this flight of stairs. You see something, you process it as the information moves to higher areas, and somewhere near the top of the stairs you become consciously aware of what you’re seeing. Yet intriguing results from patients with blindsight, along with other studies, seemed to suggest that visual awareness happens somewhere on the bottom of the stairs rather than at the top.

New, compelling demonstrations came from studies using transcranial magnetic stimulation, a method that can temporarily disrupt brain activity at a specific point in time. In one experiment, scientists used this technique to disrupt activity in V1 about 100 milliseconds after subjects looked at an image. At this point (100 milliseconds in), information about the image should already be near the top of the stairs, yet zapping lowly V1 at the bottom of the stairs interfered with the subjects’ ability to consciously perceive the image. From this and other studies, a new theory was born. In order to consciously see an image, visual information from the image that reaches the top of the stairs must return to the bottom and combine with ongoing activity in V1. This magical mixture of nitty-gritty visual details and extracted meaning somehow creates what we experience as visual awareness

In order for this model of visual processing to work, you would have to look at the photo of Aunt Betsy for at least 100 milliseconds in order to be consciously aware of it (since that’s how long it takes for the information to sprint up and down the metaphorical flight of stairs). But what would happen if you saw Aunt Betsy’s photo for less than 100 milliseconds and then immediately saw a picture of your old dog, Sparky? Once Aunt Betsy made it to the top of the stairs, she wouldn’t be able to return to the bottom stairs because Sparky has taken her place. Unable to return to V1, Aunt Betsy would never make it to your conscious awareness. In theory, you wouldn’t know that you’d seen her at all.

Mary Potter and colleagues at MIT tested this prediction and recently published their results in the journal Attention, Perception, & Psychophysics. They showed subjects brief pictures of complex scenes including people and objects in a style called rapid serial visual presentation (RSVP). You can find an example of an RSVP image stream here, although the images in the demo are more racy and are shown for longer than the pictures in the Potter study.

The RSVP image streams in the Potter study were strings of six photographs shown in quick succession. In some image streams, pictures were each shown for 80 milliseconds (or about half the time it takes to blink). Pictures in other streams were shown for 53, 27, or 13 milliseconds each. To give you a sense of scale, 13 milliseconds is about one tenth of an eye blink, or one hundredth of a second. It is also far less than time than Aunt Betsy would need to sprint to the top of the stairs, much less to return to the bottom.

At such short timescales, people can’t remember and report all of the pictures they see in an image stream. But are they aware of them at all? To test this, the scientists gave their subjects a written description of a target picture from the image stream (say, flowers) either just before the stream began or just after it ended. In either case, once the stream was over, the subject had to indicate whether an image fitting that description appeared in the stream. If it did appear, subjects had to pick which of two pictures fitting the description actually appeared in the stream.

Considering how quickly these pictures are shown, the task should be hard for people to do even when they know what they’re looking for. Why? Because “flowers” could describe an infinite number of photographs with different arrangements, shapes, and colors. Even when the subject is tipped off with the description in advance, he or she must process each photo in the stream well enough to recognize the meaning of the picture and compare it to the description. On top of that, this experiment effectively jams the metaphorical visual staircase full of images, leaving no room for visual info to return to V1 and create a conscious experience.

The situation is even more dire when people get the description of the target only after they’ve viewed the entire image stream. To answer correctly, subjects have to process and remember as many of the pictures from the stream as possible. None of this would be impressive under ordinary circumstances but, again, we’re talking 13 milliseconds here.

Sensitivity (computed from subject performance) on the RSVP image streams with 6 images. From Potter et al., 2013.

Sensitivity (computed from subject performance) on the RSVP image streams with 6 images. From Potter et al., 2013.

How did the subjects do? Surprisingly well. In all cases, they performed better than if they were randomly guessing – even when tested on the pictures shown for 13 milliseconds. In general, they scored higher when the pictures were shown longer. And like any test-taker could tell you, people do better when they know the test questions in advance. This pattern held up even when the scientists repeated the experiment with 12-image streams. As you might imagine, that makes for a very crowded visual staircase.

These results challenge the idea that visual awareness happens when information from the top of the stairs returns to V1. Still, they are by no means the theory’s death knell. It’s possible that the stairs are wider than we thought and that V1 is able (at least to some degree) to represent more than one image at a time. Another possibility is that the subjects in the study answered the questions using a vague sense of familiarity – one that might arise even if they were never overtly conscious of seeing the images. This is a particularly compelling explanation because there’s evidence that people process visual information like color and line orientation without awareness when late activity in V1 is disrupted. The subjects in the Potter study may have used this type of information   to guide their responses.

However things ultimately shake out with the theory of visual awareness, I love that these intriguing results didn’t come from a fancy brain scanner or from the coils of a transcranial magnetic stimulation device. With a handful of pictures, a computer screen, and some good-old-fashioned thinking, the authors addressed a potentially high-tech question in a low-tech way. It’s a reminder that fancy, expensive techniques aren’t the only way – or even necessarily the best way – to tackle questions about the brain. It also shows that findings don’t need colorful brain pictures or glow-in-the-dark mice in order to be cool. You can see in less than one-tenth of a blink of an eye. How frickin’ cool is that?

Photo credit: Ivan Clow on Flickr, used via Creative Commons license

Potter MC, Wyble B, Hagmann CE, & McCourt ES (2013). Detecting meaning in RSVP at 13 ms per picture. Attention, perception & psychophysics PMID: 24374558

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