Cognitive Daily reports nearly every day on fascinating peer-reviewed developments in cognition from the most respected scientists in the field.
Greta Munger is Associate Professor of Psychology at Davidson College whose works include The History of Psychology: Fundamental Questions. Dave Munger is a writer whose works include Researching Online and The Pocket Reader. And yes, he is married to Greta.
The text below will bring up an animation. Just look at it once -- no cheating! A picture will flash for about a quarter of a second, followed by a color pattern for a quarter second. Then the screen will go blank for about one second, and four objects will appear. Use the poll below to indicate which object (#1, 2, 3, or 4) appeared in the picture.
The Stroop Effect is one of the most-studied phenomena in psychology. The test is easy to administer, and works in a variety of contexts. The simplest way to see how it works is just to look the following two lists. Don't read them, instead say the color each word is displayed in, as quickly as you can:
If English is your native language, you should be much quicker at naming the colors of the first list than the second list. Why? Even though the task is to identify the colors, proficient readers can't stop themselves from reading the words, which slows color identification in cases where the color is different from the word.
But recently, Amir Raz and colleagues noticed that they could reduce and even eliminate the Stroop Effect by hypnotizing participants and suggesting to them that the words were in a foreign language, so they could focus solely on color. In a new experiment, Raz and three other researchers attempted to see if the hypnosis itself was necessary.
A number of studies have found cultural differences in visual cognition. For example, Takahiko Masuda and Richard Nisbett found that when Americans watch a short video clip of an underwater scene, they tend to recall the items in the foreground: the fish. Japanese people watching the same clip recall the items in the background: rocks, plants, and their relationship to one another.
A team led by Shinobu Kitayama showed people a frame with a line drawn inside. When asked to duplicate the line in a different-sized frame, Americans were better at drawing it the same size, despite the frame, while Japanese were better at scaling the line to correspond to the size of the new frame.
But why should such basic elements of perception vary between cultures? Most scholars have argued that social and learning differences between cultures are responsible for the difference, but Yuri Miyamoto, working with Nisbett and Masuda, wanted to explore another possibility: that these perceptual differences are due to the different physical environments in America and Japan.
Yesterday's post brings up an interesting question: How can you be unaware of having even seen an image, and yet be able to make reliable judgments about that image? That article is just one example of a variety of situations in which people can be unaware of seeing something, even immediately after being given a quick glimpse of it, yet behave as if they have seen it.
We discussed how visual images can be "masked" -- flashed quickly and then followed by another image which is displayed for a longer period. Though observers had no conscious recollection of seeing faces, they still could make accurate judgments about the attractiveness of the faces they had seen. Earlier experiments have found that the ability of the skin to conduct electricity as well as responses in the amygdala region of the brain can be affected by these masked images, again, with no conscious knowledge on the part of the viewer of having seen the image.
So how can our skin and brain respond to the image without our being conscious of seeing it? A team led by J.S. Morris developed a procedure to find out. Since the amygdala is activated during a fear response, they first conditioned volunteers to be afraid of a black and white photo of man with an angry facial expression. They used photos of four different men, two angry, and two neutral. These photos flashed randomly on the screen at intervals of around 20 seconds. When one (and only one) of the angry photos was displayed, a 1-second burst of white noise was played at a level of 100 decibels (loud enough to make you jump, but not to hurt your ears). Each face was shown six times.
Standup comics have long made vice president Dick Cheney the butt of their jokes, suggesting that he's never seen in public with the President because he inhabits some fortified underground bunker so as to avoid terrorists or some other unidentified threat, or that he's actually a cyborg, secretly controlling the government from his dark, hidden lair. But recent research in visual attention suggests that there might be another reason Cheney wouldn't want to be seen near the President. It may be that by standing next to a more famous person, your own appeal is diminished.
I'm actually only half-joking about this. Several studies, including one we've analyzed on Cognitive Daily, have taken a look at the relationship between attention and emotion: we respond quicker to emotional faces than neutral faces. Fewer studies have been conducted on the reverse phenomenon: when we search for an object, how do we react to it emotionally?
Take a look at this grid of colorized black-and-white photos: A team led by Jane Raymond showed volunteers similar grids and asked them to search for yellow males.
Babies as young as three months old will follow the eyes of an adult to look at the same thing the adult is looking at. This behavior makes sense from an evolutionary perspective: if a predator or other danger looms, we can learn from the actions of others (though it's unclear exactly what a three-month old would do to escape a ravenous bear).
But if the gaze-following behavior is really a survival adaptation, wouldn't we be more likely to follow someone's gaze if they also had a fearful facial expression? After all, if someone's glancing to the side with a cheerful smile, we don't expect they're looking at a jaguar ready to pounce. There's some evidence to support this notion. Several researchers have found that in photos of crowds, people are quicker to spot angry faces than happy faces.
A team led by Andrew Mathews showed volunteers photos of faces looking either to the left of the right, and with fearful or happy expressions. Then a letter appeared to one side of the face. While participants were faster at identifying the letter when it was on the side the face was looking at, they weren't any faster when the face had a fearful expression. So does this mean people never pay attention to the facial expression when following someone's gaze?
Take a look at the QuickTime movie below. It will show a still image for 10 seconds, then a blank screen. Then it will show you the image again. Your job is to look for a detail that has been changed between the two images.
Most people have difficulty with this task. Even when the part that changes is central to the image, accuracy is typically no better than 50 percent. For the particular type of change depicted in this movie, accuracy averages less than 30 percent. If you didn't notice the change, drag the slider in the movie quickly back and forth and you should be able to spot the change.
This phenomenon, "change blindness," has been the focus of a considerable amount of research (we've reported on it severaltimesbefore). Researchers have found that changes to "central" objects are easier to spot than "marginal" objects, but there is disagreement about what makes an object central. Is it some physical characteristic of the object itself? Or is it a cognitive process that viewers actively apply to the object?
We've reported on studies about cell phones and driving before. A general consensus has formed that driving with cell phones (even hands-free phones) is dangerous. What matters most, it appears, isn't so much the physical aspect -- holding and operating the phone -- but how demanding the conversation itself is.
Research on aging has suggested that older drivers may be even more impaired by driving with a cell phone than younger drivers, since older adults tend to perform worse on "dual task" activities than younger adults. But what about the years of driving experience that older adults have? Can't they compensate for slower reaction time with more careful driving?
David Strayer and Frank Drews had older and younger adults perform the same driving simulator task. Half of them talked on a hands-free cell phone while driving, and the other half didn't. The task was to follow a pace car in the right lane of a three-lane freeway. The pace car was programmed to randomly brake at random intervals along the 24-mile simulated course. Here's a picture of the simulator they used (from the manufacturer's web site):
Since yesterday's post on attention grabbed so much, well, attention, let's try another one. Only this time, instead of looking at what factors cause us to pay attention to something, we'll consider an experiment that studied the emotional effects of attention. If you're asked to look for people with blond hair, for example, you may eventually come to have a different emotional response to people with blond hair than others.
A team led by Mark Fenske developed a simple procedure to see if the focus of our attention can affect emotion. Twenty-four college students participated in a task that they were told was to test reaction time: two pictures of faces appeared on screen for two seconds. For a brief interval in the middle of the task, one of the faces was obscured by a semi-transparent red or green oval. If a green oval flashed, then participants had to press a designated number on the keypad as quickly as possible (4 for the left face, and 6 for the right face). If a red oval flashed, then participants were instructed NOT to respond.
I'm sure most Cognitive Daily readers are aware of the massive debate permeating the scientific world these days. No, not evolution versus creationism; I'm talking about object- versus space-based attention.
Haven't heard of this raging debate? Well, then, let me refer you to a fascinating pair of experiments conducted by Massimo Turatto, Veronica Mazza, and Carlo Umiltà. The issue comes down to this: a critical problem for psychologists is the issue of attention. How does the perceptual system decide where to focus our attention when literally millions of bits of information are available to us at a given time? The object-based school believed that attention was focused on objects: when we notice a change to one part of an object, we're more attentive to other changes in that object (e.g. when the car in front of us puts its turn signal on, we're more likely to notice it slowing down for a turn). The space-based school believed that attention was focused on particular regions: we're more likely to notice a change near where we've seen another change, whether or not the changes occur on the same object (e.g. if we see the neighbor's dog running across their backyard, we're more likely to notice the squirrel she's chasing).
Take a look at this video (click on the image to play). It's pretty clear what's going on -- the green dot bumps into the red dot, causing it to move:
But what about this one?
With this movie, it's harder to say: some people would say the green dot passes through the red dot, turning red and then moving on. Others would say the green dot launches the red dot, as before. It's an ambiguous figure.
What is your mind doing when you think about something? For decades, the prevailing wisdom was that when you imagine, say, the scent of a flower or your lover's perfume, your mind is doing something different from when you actually smell those things. The metaphor was a computer: The hardware for sensing things was distinct from the software for thinking about things.
More recent evidence suggests that the way we understand concepts relies on the sensorimotor system. When you think of the sound of a dripping faucet, the same parts of your brain are activated as when you are actually hearing a faucet dripping. (Computer geeks should see how the computer metaphor breaks down: it's as if searching a database of images required the server to access its video card.)
But if conceptual thinking requires the sensorimotor system, then thinking about concepts should have the same limitations as our senses. For example, in 2000, Charles Spence, Michael Nicholls, and Jon Driver found that the reaction time for signals was slower after a change of modalities (like touch and hearing) compared to when the modality stayed the same (for example, a visual signal followed by another visual signal).
Diane Pecher, René Zeelenberg, and Lawrence W. Barsalou designed an experiment to see if thinking about different modalities showed the same reaction-time differences. Volunteers were shown a series of simple statements and asked to indicate whether the statements were true or false. The statements all followed the same pattern: OBJECT can be PROPERTY. For example:
BLENDER can be LOUD
TOAST can be WARM
MARBLE can be COOL
BUTTERMILK can be SQUEAKING
Participants rated 300 statements. Pecher's team was interested specifically in cases where the modality of the property changed. In the list above, Blender-Loud is an auditory property, but Toast-Warm is a touch property—the modality changes. The next transition, to Marble-Cool would be an example where the modality does not change. Buttermilk-Squeaking is a decoy, as were most items on the test, so that participants didn't catch on to the real goal of the experiment. Here are the results:
Even though participants were engaged in a language task, reaction time was significantly longer when the properties they were considering came from different sensory modalities.
This appears to be compelling evidence that our thought process relies on the sensorimotor system, but the team conducted a second experiment to eliminate an alternate explanation. Perhaps we react faster merely because the words from a particular modality are more closely related linguistically than other words. In the second experiment, the team selected pairs that were very closely related: for example, the words spotless and clean. When used in the form "SHEET can be SPOTLESS" and "AIR can be CLEAN," these words aren't related to any specific modality—this is the "related word" condition. A pair such as "SHEET can be SPOTLESS" and "MEAL can be CHEAP" is an example of "unrelated words." This type of word pair was inserted in to a new experiment that also included same-modality and different-modality pairs. Here are the results:
There was no difference between related and unrelated words, but once again, a significant difference between same-modality and different-modality words was found. Pecher et al. argue that these experiments offer compelling evidence that the way we process concepts is not independent of other systems of the brain; it appears, by contrast, that conceptualization requires the use of the sensorimotor system. Unlike computers, whose highly specialized hardware often performs only a single task, the mind appears to make use of sensory systems not only for sensing, but also for imagining.
Pecher, D., Zeelenberg, R., & Barsalou, L.W. (2003). Verifying different-modality properties for concepts produces switching costs. Psychological Science, 14(2), 119-124.
Last week we discussed two experiments in a report by Adam Anderson about how the phenomenon of attentional blink is modified when the task includes arousing words. Perhaps not surprisingly, we're more likely to notice arousing words like "ejaculate" or "foreplay" in a rapidly presented sequence than neutral words like "plane" or "clock."
But Anderson wasn't finished—he wanted to explain why this phenomenon occurs. Are we more likely to remember arousing words after the fact? Or are arousing words inherently more able to attract our attention? So, Anderson reversed the attentional blink task. As before, participants were shown a rapidly flashed sequence of words, appearing randomly in different colors. The task was to identify two words displayed in different colors from the rest: a first word displayed in white, and a second green word. The white "word" was always a sequence of digits (00000000000, 55555555555), and the second word was a neutral word (mirror, surplus). However, all the other words in the sequence were randomly chosen from either a set of arousing or neutral words. Given this massive distraction, how accurate were participants at identifying the words?
Overall, compared to previous experiments, they were much less accurate—and when the distractors were arousing, performance was consistently worse than for neutral distractors. Given that in both cases, participants are not being asked to remember the arousing words, this result suggests that the diminished attentional blink associated with arousing words is not due to arousing words being more memorable, but because they are more likely to attract our attention in the first place.
But perhaps when we see an arousing word, we direct more attention to it because we exclude other objects from our attention. Seen this way, attention is a matter of different inputs competing for our mind's limited processing resources. Perhaps arousing words are simply those that are better able to use these resources. The other possibility is that attention overall is improved when we are aroused. To try to differentiate between these possibilities, Anderson designed another experiment. As in previous experiments, participants were asked to identify two words, one displayed in white and a second in green, among a rapidly presented list of distractor words in black. This time, participants were encouraged to identify the first word (actually either a sequence of Xs or Os) as rapidly as possible. The second word was either an arousing or a neutral word. The basic results were the same as in other tests: for neutral words, an attentional blink occurred for about 400 milliseconds after the first word, and for arousing words, this blink was diminished. But I want to focus in on another set of results, which compare reaction time for the first word with accuracy on the second word:
Participants who had the fastest reaction times to the first word (in quartile 1) were also the most accurate at identifying the second word. However, when viewing arousing words, accuracy remained relatively high regardless of reaction time. With neutral second words, accuracy diminished as response time increased. This result too suggests that arousing words aren't merely more memorable than neutral words—they're better at attracting our attention in the first place. Even more interesting is how quickly this effect occurs. Anderson switched between arousing and neutral words between each trial of the experiment. So the arousing words aren't simply increasing our overall attentive state, they're intrinsically more noticeable.
If these words increased our overall ability, we should see some increase in attention to non-arousing words. Instead attending to these words appears to be a spur-of-the-moment thing: we notice them when they're there; we don't notice other words under similar circumstances.
What does this suggest about the attention system overall? While it's certainly an indepent system of the mind (we still attend to new things even while doing something else), it's also linked into other systems. Emotion, as shown in Anderson's work, has a critical link to attention. Unraveling how these different systems interact with each other will become a critical part of the study of cognition in the future.
Anderson, A.K. (2005). Affective influences on the attentional dynamics supporting awareness. Journal of Experimental Psychology: General, 134(2), 258-281.
A few months ago, Jon Stewart opened the eyes of his Daily Show audience when he interviewed the author of the book On Bullshit. Viewers accustomed to hearing the familiar bleep when Stewart enters foul-mouth mode were surprised to find that the word came through completely uncensored. Stewart himself reveled in his new freedom, repeating the word "bullshit" dozens of times over the course of the interview. It was difficult not to notice the word every time he spoke it.
Adam K. Anderson of the University of Toronto, who specializes in studying attention, wondered if negative words like "bullshit" were more likely to attract our notice even during times when we're normally distracted. He designed a version of the attentional blink paradigm to include three types of words: neutral (bread, branch), negative (blood, beaten), and negative-arousing (bitch, bastard). The words were rated by a panel of volunteers for negative value and arousal to ensure that the categories were accurate.
Attentional blink research has found that when people view a series of words presented rapidly and try to identify two words that are different from the rest (e.g. a different color or meaning from the other words in the series), they fail to recall the second word if it is displayed during a short span (about 200 to 500 milliseconds) after the first one. In Anderson's version of the task, participants had to recall the two green words in a list of black words, displayed slide-show fashion for a tenth of a second each. The first green word was neutral, and the second green word was either neutral, negative, or negative-arousing. Here are his results:
When the second green word was neutral, the standard result for attentional blink occured: when the second word was displayed immediately after the first, recall was relatively accurate, but if it was two to four places after the first, recall suffered, before finally increasing above 90 percent accuracy after seven or so places. Negative words showed less attentional blink, and for negative-arousing words, the effect was nearly absent. So despite the fact that we usually don't notice distinctive words when they are displayed so soon after another, we do notice taboo words in the same circumstances.
But is it the fact that these words are negative that causes us to notice them, or is it arousal? Anderson generated a new set of words in three new categories: neutral (crowbar, square), positive (champ, sweet), and positive-arousing (condom, sensual). This time, he modified the attentional blink task—instead of noticing two green words, participants had to identify a first "word" that was just a sequence of letters (LLLLLLLLL, VVVVVVVVV) colored white, along with the second green word, chosen from the neutral, positive, and positive-arousing lists. The other words in the list were displayed in different (non-green or white) colors. Here are the results:
Because the task was modified, the data follows a different pattern. When the green word immediately followed the set of white letters, accuracy was the worst. Accuracy steadily improved until the fourth position, when it topped out near 90 percent. But otherwise, the results followed a similar pattern to the negative words: less attentional blink for positive words, and almost none for positive-arousing words.
So though we do notice negative-arousing words like Jon Stewart's favorite, "bullshit," more often than neutral words, we also notice positive words. Positive or negative, arousing words are the most noticeable of all. So what causes us to notice these words? Anderson has some answers, but they'll have to wait until the next Cognitive Daily post. Come back next week and read all about it!
Anderson, A.K. (2005). Affective influences on the attentional dynamics supporting awareness. Journal of Experimental Psychology: General, 134(2), 258-281.
Take a look at these two photographs of my son Jim taken a month or so after he was born (and, as he would be quick to point out, nearly 14 years ago). Which is more memorable?
It may depend on your age. It's natural for your priorities to change as you get older, and so it seems, you may have a different response to pictures depicting emotions. Your kids grow up and leave home, and suddenly Little League and Disney seem less significant. Perhaps fine wine and opera rise up to fill that void. Later still, you begin to think about retirement, and gradually it seems more important to reach out to family and friends. Laura Carstensen was part of a group of researchers who developed a "socioemotional selectivity theory" to explain these changes—they argued that our emotion-related goals increase in importance as we age because we are assessing how much longer we have to live.
As we age, they claim, emotion increasingly becomes the central motivator for a wide sphere of actions, from who we choose to spend time with to how we deal with problems. Perhaps surprisingly, this reorienting of goals around emotions, all motivated by impending death, leads to the result that older adults are better off emotionally than younger people.
Carstensen joined with Martha Mather to expand on these conclusions—they wanted to see if this focus on emotions in older adults also affected cognition, and so they developed a simple reaction-time and memory test. Two groups of people participated in the study: older adults with an average age of 74, and younger adults averaging age 26. They were questioned about their emotional state, and consistent with socioemotional selectivity theory, the younger adults scored significantly lower than older adults on an index of negative emotion.
The participants were shown pairs of photos of 60 different faces. Each pair of photos depicted the same person: one with a neutral expression, and one showing an emotion— happy, sad, or angry. The photos remained on screen for 1 second, then disappeared. In place of one of the photos, a small grey dot appeared, and participants were asked to press a button on the keyboard to indicate where the dot had appeared (left or right).
As you might expect, the younger adults responded much faster than older adults—in about 420 milliseconds compared to 780 for older adults. But when responses to emotional faces were compared to those for neutral faces, another striking difference appeared:
These results were obtained by subtracting the average reaction time for the emotional face from the reaction time for the neutral face in a pair. For younger people, there was no significant difference in reaction times between emotional faces and neutral faces, or even between positive and negative faces. For older people, the emotion difference in the faces caused a comparatively large difference in reaction times. The slowest reaction times were always for negative faces, and the fastest times were for positive faces.
After participants completed the reaction time test, Mather and Carstensen tested memory. They showed viewers a new set of paired photos, each containing one previously-viewed face and one new face. The emotions in these new pairs of photos always matched: the task was to indicate which face they had seen before. Here are the results:
When the emotion for the test pair was happy and the original pair of photos had been happy/neutral, older adults were significantly more likely to correctly recall the old picture than for any other condition. While younger adults were somewhat less likely to remember old negative faces, for the most part the emotion of the faces did not impact their memory for faces.
Mather and Carstensen conclude that these results show not only that subjective attention to emotional issues change as we age, but also the way our basic cognitive processes work when we are confronted with emotional images. Motivated by impending death, emotion affects our life priorities, but these important changes as we age also impact our ability to react to and remember simple images.
Mather, M., & Carstensen, L.L. (2003). Aging and attentional biases for emotional faces. Psychological Science, 14 (5), 409-415.
The picture below will link you to a quick animation. The blue ring will gradually get smaller until it obscures the three "8"s, then continue to shrink until the figures are visible again. While they are obscured, the 8s will be transformed into letters (S, P, E, U, or H), and a new letter will also appear. Your job is to search for the letter U or H—it has an equal chance of appearing where any of the 8s were, or in the new spot. Click on the picture to try it out.
Attention researchers Steven Franconeri, Andrew Hollingworth, and Daniel Simons used a similar animation to answer a key question about what attracts our attention. Recent research has led to two different hypotheses—either the appearance of a new object, or a change in the luminance (brightness) of an area of our field of view is what attracts our attention.
In many cases, both of these changes occur at the same time. For example, we're driving down the street and a boy runs out in front of our car chasing a ball. The boy appearing in front of our car is certainly a new object, and the light reflecting off of his sweatshirt carries a different luminance value from the asphalt pavement we had been looking at.
Franconeri and his colleagues cleverly designed the animated display you just looked at to introduce a new object without a corresponding change in luminance: the object was introduced while all four objects were obscured by the blue ring, so when it appeared, there was no luminance change.
In a separate condition, the group presented the same animation, with the ring passing behind the letters, so that when the new object appeared, there was a change in luminance. They repeated the task with 2, 3, and 4 objects in the final display; in each case, participants knew that the 8s would change into letters, and that they'd be searching for a U or an H. Here are their results:
When the ring passes in front of the letters, there is no difference in reaction time, whether the target letter (U or H) appears in a new position or an old position. This suggests that the mere fact of a new letter appearing doesn't attract our attention, because if it did, we'd react more quickly when the target letter appeared in a new position. Compare this to the control condition, where the letters are always in view:
Now, reaction time is significantly faster for the new item. So when a new item actually changes the luminance of an area in our field of view, we react faster. Franconeri and his team argue that this result supports the luminance hypothesis. They suggest that when the new item corresponds to a luminance change, we direct our attention to that new item. Then we are able to complete the task more quickly—to determine if that item is an H or a U. So a change in luminance attracts our attention, but the appearance of a new object on its own does not.
Franconeri, S.L., Hollingworth, A., & Simons, D.J. (2005). Do new objects capture attention? Psychological Science, 16(4), 275-281.
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Cognitive Daily reports nearly every day on fascinating peer-reviewed developments in cognition from the most respected scientists in the field.
