Perception

People with anxiety show fundamental differences in perception

Posted by

0


People with anxiety fundamentally perceive the world differently, according to a new study. They aren’t simply making the choice to ‘play it safe.’

People with anxiety fundamentally perceive the world differently, according to a study reported in the Cell Press journal Current Biology on March 3. They aren’t simply making the choice to “play it safe.”

The new study shows that people diagnosed with anxiety are less able to distinguish between a neutral, “safe” stimulus (in this case, the sound of a tone) and one that was earlier associated with the threat of money loss or gain. In other words, when it comes to emotional experiences, they show a behavioral phenomenon known as over-generalization, the researchers say.

“We show that in patients with anxiety, emotional experience induces plasticity in brain circuits that lasts after the experience is over,” says Rony Paz of Weizmann Institute of Science in Israel. “Such plastic changes occur in primary circuits that later mediate the response to new stimuli, resulting in an inability to discriminate between the originally experienced stimulus and a new similar stimulus. Therefore, anxiety patients respond emotionally to such new stimuli as well, resulting in anxiety even in apparently irrelevant new situations. Importantly, they cannot control this, as it is a perceptual inability to discriminate.”

In the study, Paz and his colleagues trained people with anxiety to associate three distinct tones with one of three outcomes: money loss, money gain, or no consequence. In the next phase, study participants were presented with one of 15 tones and were asked whether they’d heard the tone before in training or not. If they were right, they were rewarded with money.

The best strategy was not to mistake (or over-generalize) a new tone for one they’d heard in the training phase. But the researchers found that people with anxiety were more likely than healthy controls to think that a new tone was actually one of the tones they’d heard earlier. That is, they were more likely to mistakenly associate a new tone with money loss or gain. Those differences weren’t explained by differences in participants’ hearing or learning abilities. They simply perceived the sounds that were earlier linked to an emotional experience differently.

Functional magnetic resonance images (fMRIs) of the brains of people with anxiety versus healthy controls showed differences in brain responses, too. Those differences were mainly found in the amygdala, a brain region related to fear and anxiety, and also in primary sensory regions of the brain. These results strengthen the idea that emotional experiences induce changes in sensory representations in anxiety patients’ brains.

The findings might help to explain why some people are more prone to anxiety than others, although the underlying brain plasticity that leads to anxiety isn’t in itself “bad,” Paz says.

“Anxiety traits can be completely normal, and even beneficial evolutionarily. Yet an emotional event, even minor sometimes, can induce brain changes that might lead to full-blown anxiety,” he says.

How Good Is Your Eyesight And Perception?

Posted by

0


How Good Is Your Eyesight And Perception?

Eyes performance varies from person to person. Are you one of those who have 20/20 or an average vision? Does your vision has flaws or you have a clear vision. The Snellen chart is the most famous vision test, but there are alternative ways to find out how well your vision functions. This test is one of them. It evaluates how well your eyes can interpret, differentiate, adjust and focus on the images it’s taking in. If the results of the test are not that impressive then it would be a good idea to see an eye doctor for a professional examination.

How Good Is Your Eyesight? (And Perception)

Youngest born ‘perceived as shorter’

Posted by

0


girls legs

Mothers perceive their youngest children as shorter than they actually are, a study suggests.

This “baby illusion” applies regardless of the number of children a mother has, Current Biology reports.

Mothers underestimated the height of their youngest child by an average of 7.5cm (3in), yet accurately judged the height of any older children they had.

The study authors believe this is an adaptive mechanism – to nurture and protect most vulnerable offspring.

Always the baby

The Australian researchers surveyed 747 mothers, asking them if they remembered experiencing a sudden shift in their youngest son or daughter’s size immediately after the birth of a new baby.

More than two-thirds (70%) said they did.

This perceptual shift primarily relates to the former “baby” of the family – mothers were less likely to report any height difference in other siblings.

This is not just because the older child looks so big compared with a baby, the researchers say.

It actually happens because all along the parents were under an illusion their child was smaller than he or she really was. When the new baby is born, the spell is broken and parents now see their older child as he or she really is, they say.

The researchers asked 70 mothers to estimate – by putting a mark on a wall – the height of each of their children.

The mothers consistently underestimated the height of their only or youngest children (aged two to six).

Yet many were good at estimating the height of their older children and everyday objects, such as the bathroom sink or kitchen counter.

Lead researcher Jordy Kaufman, of Swinburne University of Technology, said: “Our research potentially explains why the ‘baby of the family’ never outgrows that label. To the parents, the baby of the family may always be ‘the baby’.”

What color is an orgasm?

Posted by

0


People with a condition known as synesthesia are prone to swapping their senses. They can feel colors, see music, and smell words. This raises an important question for science: What’s it like to have sex when you’ve got synesthesia? Thanks to some inquisitive researchers, we have the answer.

People with synesthesia (aka “synesthetes”) experience the world differently than most. Their neurological pathways are jumbled in such a way that they associate seemingly unrelated senses or mental states with other senses or experiences. The most common form of the condition is grapheme-color synesthesia, wherein individual numbers and/or letters of the alphabet induce the visual perception of specific color patterns. Other, less-common forms of cross-sensory variation abound, and include lexical-gustatory synesthesia (words are associated with taste), chromesthesia (sound-color synesthesia) and auditory-tactile (sound-touch) synesthesia.

Sex, for the uninitiated, involves a fair bit of touching, tasting, hearing, seeing and yes, even counting. Needless to say, there’s a whole lot of sensory and emotional stimulation at work in your typical bout of whoopee-making, and therefore plenty of opportunities for a synesthete’s neurobiology to go positively frantic with crosstalk. But so then what is sex like for a synesthete?

As it turns out there’s not a lot of writing on the subject, and what we do know is frustratingly vague. Previous research, for example, suggests that orgasm can induce the visual perception of color in a little over 2% of synesthetes. “Kissing and sexual intercourse is a reliable trigger,” writes Richard Cytowic in his book Synesthesia: A Union of the Senses, “causing colored photisms, tactile shapes and textures and tastes.” Similarly, touching, caressing and petting (all tactile sensations) are known to induce the concurrent perception of colors, flavors, smell, sounds, and even temperatures. But what of the really nitty gritty details? What does an erection smell like (to a synesthete, weirdo)? What color is an orgasm?

Spurred by the lack of investigation into synesthetic perceptions of intercourse, researchers led by Hannover Medical School’s Markus Zedler decided to examine whether these perceptions “have an impact on the sexual experience and the extent of sexual trance compared to non-synaesthetes.” Writes Zedler, in the latest issue of Frontiers in Psychology:

In total, 19 synaesthetes with sexual forms of synaesthesia (17 female; 2 male) were included as well as corresponding control data of 36 non-synaesthetic subjects (n = 55). Two questionnaires were used to assess relevant aspects of sexual function and dysfunction (a German adaption of the Brief Index of Sexual Functioning, KFSP) as well as the occurrence and extent of sexual trance (German version of the Altered States of Consciousness Questionnaire, OAVAV). Additionally qualitative interviews were conducted in some subjects to further explore the nature of sexual experiences in synaesthetes.

The upshot of the study, which you can read in full here, is that sexual synesthetes “seem to experience a deeper state of sexual trance without, however, enhanced satisfaction during sexual intercourse.” That’s all well and good, but of particular note is the table of “exemplary citations” that Zedler and his colleagues created based on their qualitative interviews with sexual synesthetes, regarding how they experience different stages of the sexual response cycle. It is, in a word, excellent:

Recently, a handful of researchers have argued that most people experience synesthesia-like sensations to some degree, but most agree that the percentage of people who experience them keenly is relatively small. Which we suppose makes sense. After all, how many times has your post-coital pillow talk played out like this:

“Was it good for you?”

“Yeah, the wall exploded and my vision went purple. You?”

“Same. Hey, why do you look all yellow?”

Source:  Frontiers in Psychology.

Solving the Mystery of the Shrinking Moon.

Posted by

0


Introduction
Have you ever noticed how the moon appears much bigger at the horizon, just as it is rising over the nearby buildings or treetops, than it does later in the evening when it is directly overhead? Of course, the moon’s size does not change, but our perception of its size changes based on its position in the sky. In this activity you’ll investigate Emmert’s law, which helps explain the full-moon illusion, and estimate the size of the perceived increase in size of the moon when it is near the horizon. Then you could check out the real moon and see how this activity holds up to the full-moon illusion.

full-moon-line

Background
A full moon rising over the horizon often seems to be unusually large, but looks smaller as it moves up in the sky. The actual size of the moon stays the same. So what is the basis for this illusion? One well-supported theory is that the brain “thinks” the sky overhead is closer than the sky at the horizon and it adjusts the size of the moon’s image accordingly. When the moon is near the horizon, your brain miscalculates the moon’s true distance and size, making it seem larger in relation to its surroundings.

One way to explore this illusion is with afterimages. These occur when certain light-sensing cones in your eyes become fatigued after staring at a bright—or brightly colored—object. You can manipulate afterimages to mimic your perception of the moon at different places in the sky. Although the actual size of a specific afterimage on your retina doesn’t change, its perceived size can, depending on your perception of how far away the surface on which you view it seems to be. This phenomenon is known as Emmert’s law.

Materials
• A sheet of blue construction paper (A blue pen or pencil can be used instead, but the colored paper is best.)
• Scissors
• Glue or tape
• A sheet of yellow construction paper (A white sheet of paper can be used instead, but is less preferable.)
• A timer or a clock that shows seconds
• A helper
• An area with a clear view of the horizon and the zenith (the region of the sky directly overhead) (This part of the activity should be done mid-morning or mid-afternoon—to avoid looking at the sun—and on a day that is fairly cloudless with a lot of blue sky.)

Preparation
• Cut a square out of the blue construction paper sheet, about one to two inches on each side.
• Lay the yellow sheet of construction paper down in the landscape position (long-ways horizontal). Fold the paper in half (taking the right side of the paper and folding it over the left side). Then unfold the paper.
• Using glue or tape, attach the blue square to the yellow sheet of construction paper, in the middle of either the left or right half of the yellow sheet. Be careful not to cover the top of the square or yellow sheet with the tape or glue.
• If you do not have construction paper, you may draw a solid blue square on either the right or left side of a plain white sheet of paper, as described.

Procedure
• You can complete the first part of this activity inside: Hold the yellow paper with the blue square in front of you. Stare at the blue square for 30 seconds. (Use a timer with a buzzer or have a helper watch a clock for you.) Without changing the distance between your head and the yellow paper, switch from looking at the blue square to looking at the empty half of the yellow paper. Do you see the afterimage of the square? If you cannot clearly see an afterimage, try repeating this step until you can.
• Once the afterimage fades, keep your head the same distance from the paper as it was before and again stare at the blue square for 30 seconds. Then look for the afterimage on the empty half of the yellow paper. But this time try moving your head away from or closer to the yellow paper. How does the size of the afterimage change as you change the distance between your head and the yellow sheet? If you could not clearly see a change, try repeating this step until you can.
• Overall, how did the size of the afterimage change as you changed the distance between your head and the yellow paper?
• Next, go outside to an area with a clear view of the horizon and zenith. Do not do this at noon, when the sun is directly overhead or at twilight when the sun is low on the horizon, because this interferes with your observation of the afterimage at the zenith (the sky directly overhead) or the horizon. Mid-morning or mid-afternoon is probably the best time to do this, and the day should be fairly cloudless with a lot of blue sky to look at. Remember: when choosing the section of the sky to use, be sure that it does not coincide with where the sun is—you should never  look directly into the sun.
• Stare at the blue square on the yellow sheet for 30 seconds and then look at the horizon. Is there an apparent change in the size of the afterimage? In other words, does the afterimage look smaller, larger or the same size as the blue square? You can repeat this step a few times if you are unsure of your observations.
• Next stare at the blue square for 30 seconds and then look at the zenith. Is there an apparent change in the size of the afterimage? Does the afterimage look smaller, larger or the same size as the blue square? Again, you can repeat this step if you are unsure of your observations.
• Overall, did the afterimage appear smaller, larger or the same size at the horizon compared with its appearance at the zenith?
• Extra: Try the first part of this activity again (before you go outside), but this time try to quantify how the size of the afterimage changes depending on the distance between your head and the yellow sheet. (Be sure to always stare at the blue square from the same distance.) You could put the yellow sheet on a wall next to a ruler to estimate the size of the afterimage. Alternatively you could draw several different size squares (some bigger and some smaller than the blue square) nested together on the yellow sheet and try to see in which square the afterimage fits best. How does the distance between your head and the afterimage quantitatively correlate to the afterimage size?
• Extra: Try to estimate the change in the size of the afterimage at the zenith compared with the horizon. To do this you could cut out several squares (a white sheet of paper would work), some smaller and some larger than the blue square, and hold them out at arm’s length when looking at the afterimages. Try to find the squares that are most similar in size to the afterimages. Based on your findings, what is roughly the magnitude of the change of the full moon’s apparent size between the horizon and the zenith?
• Extra: Try to estimate the change in the size of the afterimage at 45 degrees above the horizon; that is, halfway between the horizon and the zenith. (Be sure to avoid the part of the sky with the sun.) What is the relative size of the afterimage at 45 degrees above the horizon, and how does it compare with the afterimage’s sizes at the zenith and the horizon?

Observations and results
When you stared at the blue square, and then looked at the yellow sheet and moved your head away from or closer to the sheet, did the size of the afterimage increase with distance? Did the afterimage look bigger on the horizon compared with its size at the zenith?

Whereas the actual size of the afterimage on your retina doesn’t change, the perceivedsize of the afterimage actually grows as you increase the distance between you and the surface on which you view the afterimage. (Or, in other words, the perceived afterimage size decreases as you get closer to the surface you’re viewing it on.) This phenomenon is known as Emmert’s law. One theory for why we perceive the full moon to be larger at the horizon compared with the zenith is that we perceive the sky overhead, at the zenith, as being closer than the sky at the horizon. In this activity this should have been apparent using afterimages; the afterimage at the horizon should have appeared larger than the afterimage at the zenith (although maybe only by a little, such as approximately 1.3 to 1.5 times larger at the horizon, depending on the exact conditions).

Source: http://www.scientificamerican.com

Why you think your phone is vibrating when it is not?

Posted by

0


Most of us experience false alarms with phones, and as Tom Stafford explains this happens because it is a common and unavoidable part of healthy brain function.

cell

Sensing phantom phone vibrations is a strangely common experience.Around 80% of us have imagined a phone vibrating in our pockets when it’s actually completely still. Almost 30% of us have also heard non-existent ringing. Are these hallucinations ominous signs of impending madness caused by digital culture?

Not at all. In fact, phantom vibrations and ringing illustrate a fundamental principle in psychology.

You are an example of a perceptual system, just like a fire alarm, an automatic door, or a daffodil bulb that must decide when spring has truly started. Your brain has to make a perceptual judgment about whether the phone in your pocket is really vibrating. And, analogous to a daffodil bulb on a warm February morning, it has to decide whether the incoming signals from the skin near your pocket indicate a true change in the world.

Psychologists use a concept called Signal Detection Theory to guide their thinking about the problem of perceptual judgments. Working though the example of phone vibrations, we can see how this theory explains why they are a common and unavoidable part of healthy mental function.

When your phone is in your pocket, the world is in one of two possible states: the phone is either ringing or not. You also have two possible states of mind: the judgment that the phone is ringing, or the judgment that it isn’t. Obviously you’d like to match these states in the correct way. True vibrations should go with “it’s ringing”, and no vibrations should go with “it’s not ringing”. Signal detection theory calls these faithful matches a “hit” and a “correct rejection”, respectively.

But there are two other possible combinations: you could mismatch true vibrations with “it’s not ringing” (a “miss”); or mismatch the absence of vibrations with “it’s ringing” (a “false alarm”). This second kind of mismatch is what’s going on when you imagine a phantom phone vibration.

For situations where easy judgments can be made, such as deciding if someone says your name in a quiet room, you will probably make perfect matches every time. But when judgments are more difficult – if you have to decide whether someone says your name in a noisy room, or have to evaluate something you’re not skilled at – mismatches will occasionally happen. And these mistakes will be either misses or false alarms.

Alarm ring

Signal detection theory tells us that there are two ways of changing the rate of mismatches. The best way is to alter your sensitivity to the thing you are trying to detect. This would mean setting your phone to a stronger vibration, or maybe placing your phone next to a more sensitive part of your body. (Don’t do both or people will look at you funny.) The second option is to shift your bias so that you are more or less likely to conclude “it’s ringing”, regardless of whether it really is.

Of course, there’s a trade-off to be made. If you don’t mind making more false alarms, you can avoid making so many misses. In other words, you can make sure that you always notice when your phone is ringing, but only at the cost of experiencing more phantom vibrations.

These two features of a perceiving system – sensitivity and bias – are always present and independent of each other. The more sensitive a system is the better, because it is more able to discriminate between true states of the world. But bias doesn’t have an obvious optimum. The appropriate level of bias depends on the relative costs and benefits of different matches and mismatches.

What does that mean in terms of your phone? We can assume that people like to notice when their phone is ringing, and that most people hate missing a call. This means their perceptual systems have adjusted their bias to a level that makes misses unlikely. The unavoidable cost is a raised likelihood of false alarms – of phantom phone vibrations. Sure enough, the same study that reported phantom phone vibrations among nearly 80% of the population also found that these types of mismatches were particularly common among people who scored highest on a novelty-seeking personality test. These people place the highest cost on missing an exciting call.

The trade-off between false alarms and misses also explains why we all have to put up with fire alarms going off when there isn’t a fire. It isn’t that the alarms are badly designed, but rather that they are very sensitive to smoke and heat – and biased to avoid missing a real fire at all costs. The outcome is a rise in the number of false alarms. These are inconvenient, but nowhere near as inconvenient as burning to death in your bed or office. The alarms are designed to err on the side of caution.

All perception is made up of information from the world and biases we have adjusted from experience. Feeling a phantom phone vibration isn’t some kind of pathological hallucination. It simply reflects our near-perfect perceptual systems trying their best in an uncertain and noisy world.

Source: BBC