Perception
dmunger | September 3, 2008You may have heard of the idea that people can only remember seven things at a time -- a seven-digit phone number, a license-plate, etc. While the size of working memory actually varies from person to person (it usually ranges from 6 to 8 items), and while people can use strategies like "chunking" to remember more, this observation is basically true.
Except when it's not true. In the 1970s, researchers found that there are actually at least two different and distinct areas of working memory, each with its own separate capacity. One is called the "phonological loop" and is used for recall of…
dmunger | August 27, 2008"Impossible objects" like the etchings of M.C. Escher have fascinated adults for centuries. You can't help but stare and wonder at a drawing like this, which seems to defy the laws of nature:
The drawing seems strange to us because our visual system tells us that when an object or part of an object occludes another, it's in front. Since the parts of the cube are all connected, it's clear that the vertical bar in the "back" of the cube shouldn't be in front of any other bars.
Some research has suggested that young babies don't have the same ability as adults to determine how close objects…
dmunger | August 21, 2008As a child (and like most children, I imagine) I used to think conducting an orchestra entailed something like what Bugs Bunny does in this video:
Waving the hands, as conductors frequently do, seemed largely for show. The conductor appeared to me to be more dancing along with the music than actually leading the musicians in any meaningful way. It wasn't until I married an amateur musician that I actually learned that the conductor could have an important influence on the way an orchestra sounds. But as Greta and I moved from place to place and she joined a variety of different ensembles, I…
edyong | August 19, 2008When you look at someone's face, what part do you concentrate on? Common wisdom has it that the eyes are the focal point of the face and they are the features that draw attention first. But according to a new study, that may not be universally true - while Western cultures do fixate on the eyes, East Asians tend to focus on the nose.
We owe a lot of our knowledge about the way we look at images to a Russian psychologist Alfred Yarbus. He was the first scientist to carefully record the subtle eye movements that people make when they take in a view. Yarbus's experiments showed that our gaze…
dmunger | August 7, 2008[This article was originally published in April, 2007]
There is a considerable body of research showing that eye contact is a key component of social interaction. Not only are people more aroused when they are looked at directly, but if you consistently look at the person you speak to, you will have much more social influence over that person than you would if you averted your gaze.
The problem arises when you address a group of people. How do you pick who to engage visually? Most public speakers are encouraged to look around the room, alternating eye contact with individuals in the audience…
dmunger | August 4, 2008[Originally posted in May, 2007]
"I just didn't see him" is a claim that's repeated over and over in accident reports. Drivers earnestly claim that they simply didn't notice the bicycle/pedestrian/motorcycle they crashed into. The claim is made so frequently that certainly there must be a grain of truth to it. Yet it certainly isn't the case that car drivers can't see such obstacles -- after all, they can see traffic signals that are much smaller than a bike or a motorcycle.
What they mean to say is that their attention was otherwise engaged -- perhaps by a phone conversation, perhaps by…
dmunger | July 24, 2008Several recent large-scale studies have confirmed a curious finding: Asians are much more likely to have "perfect pitch" than non-Asians. Perfect pitch, more properly called "Absolute pitch," is an extremely rare phenomenon, but it's several times more likely to occur in Asians than in others.
Studies have found that only 1 in 1,500 to 10,000 individuals possess absolute pitch. Part of the ability's rarity is due to the fact that it's really a combination of two abilities: pitch-memory -- the ability to remember what a pitch sounds like, and pitch-labeling -- the ability to name a pitch (A, B…
dmunger | July 21, 2008A number of studies have found that older adults aren't as good at certain visual tasks compared to younger adults. Mental rotation, for example, is both slower and less accurate. But other studies have found that for certain types of mental rotation, older adults do just as well as younger adults. The dividing line, these researchers argued, was based on whether the viewer was rotating or the objects themselves were rotating.
So in a classic mental rotation task like Shepard and Metzler's, older adults don't do as well, but in many other tasks, their performance isn't much different from…
dmunger | July 17, 2008When we're in a crowded space, making visual judgments becomes more difficult. But it doesn't take much to trigger a crowding effect. Clicking on the picture below will take you to a quick movie (QuickTime required) that should demonstrate the effect. Focus on the cross to the left, then start the movie (it may start automatically, depending on your browser). In two seconds, a "T" will flash briefly on the right side of the screen. Your job is to determine whether the T is upright or inverted (upside-down). After another two seconds, three Ts will appear. This time, you must judge only the…
edyong | July 15, 2008Which of these strings of letters is easier to remember: QKJITJGPI or BBCITVCNN?
Chances are, you chose the latter string, where the nine letters are the combined names of three television networks. This neatly illustrates a fundamental property of human memory - that we remember long strings of information more easily if we can break them down into bite-sized chunks. In this case, a nine-letter string can be divided into three lots of three letters. You probably use similar strategies for remembering telephone numbers, credit card details, or post codes.
Now, Lisa Feigenson and Justin…
dmunger | July 15, 2008Imagine yourself in a room surrounded by eleven objects arranged in a circle. You memorize the position of the objects, then you close your eyes, and rotate a third of the way around (120°). Keeping your eyes closed, can you point to the object that was behind you before? Most people can do this without much difficulty, and only take an instant longer than if they'd stayed in the same position.
Now imagine the objects are rotating on a turntable as you yourself rotate, so that the same object is still in front of you -- in many respects, it's as if you've never turned and the objects never…
dmunger | July 9, 2008In 2005, E. Ashby Plant and B. Michelle Peruche tested 48 Florida police officers and found that they were initially more likely to shoot unarmed Black "suspects" in a crime-fighting simulation than White people holding similar objects. Interestingly, however, as the test went on, the officers improved, and by the end of the session, any bias had been removed.
But in the real world, officers don't get a second chance, and accidental shootings do occur. In many communities, racial tensions are already running high, and an interracial shooting by a police officer can bring those tensions to the…
dmunger | July 7, 2008Last year we discussed a great deal of research about the gender disparity in math and science. Even while women are more successful overall in school than men, in certain fields there is a very large deficit in the number of women participating. We mentioned one explanation in particular:
The male math advantage in a number of different studies appears to be directly related to visuospatial skills, the most important being mental rotation. In tests on calculation or other mathematical problems that don't require visuospatial skills, females perform just as well as -- or better than -- males…
dmunger | June 17, 2008What makes something look glossy? At first, it doesn't seem like a difficult question -- it's something smooth and reflective. But if you were to attempt to draw something that looked glossy, how would you to it? Now, the problem suddenly gets a lot more difficult. Taking a look at a photo of a glossy object might give you some clues. Here's an example:
I took this picture of my watch using the webcam on my computer. Notice that you can see the reflection of the computer screen in the bottom half of my watch face. You can't see it on my face though -- my face isn't glossy. So one component…
dmunger | June 16, 2008Listen to this short audio clip:
The clip plays two notes that are two full octaves apart. That's a greater range than many people can produce vocally. It should be easy for anyone to tell the difference between these two notes, even when heard in isolation, right?
Not necessarily.
A team led by Ulrich Weger has found a scenario where people make systematic errors judging these two very different notes. While most people get the notes right most of the time, by introducing a wrinkle into the testing, Weger's team could reliably induce errors and slower response times.
They asked 20…
edyong | June 15, 2008Show someone a piece of rotting food and their reaction will be visibly similar the world over. Their eyes will close, their noses will wrinkle and their mouths will tighten, all part of a universal expression of disgust. Darwin himself was struck by the universal nature of human facial expressions - from the busiest of cities to the most isolated of villages, smiles and frowns are recognisable, done in the same way and carry the same meaning.
Facial expressions are massively important for the social lives of humans and it should come as no surprise that some parts of our brain are dedicated…
dmunger | June 12, 2008Boundary extension -- misremembering the boundaries of a scene as wider than they really are -- has been observed in adults as old as 84 and children as young as 6. But for kids much younger than 6, the phenomenon becomes quite difficult to study. How do you ask a 6-month-old whether the picture they're looking at has the same borders as one they saw a few minutes ago? You can't ask them to draw the picture for you -- they can barely sit up, let alone hold a pencil.
Yet the development of boundary extension is an important aspect of the study of vision. Do babies experience the phenomenon…
dmunger | June 11, 2008Take a look at these three pictures. Can you tell which is a human, which is a cat, and which is a pigeon?
How about these three pictures? A little easier?
It would be even easier, of course, if the pictures were in motion, like in this movie (QuickTime required). (Update: Nikolaus Troje has provided a link to a full set of demos here -- check them out, they're awesome!) The difference between the first three pictures and the second three is that the points that make up each animal's body parts have been scrambled in the first set of pictures. Why? Because the researchers Dorita Chang and…
dmunger | June 3, 2008Take a look at the short movie I've linked below (Click on the picture to play. QuickTime required). The movie shows a virtual gripping device (two red balls) lifting rectangular objects and placing them on a conveyor belt. Do you notice anything unusual happening as the objects are being moved?
This is a recording of the image seen by a volunteer using a virtual-reality headset and two force-feedback devices to simulate moving objects by picking them up with a thumb and index finger. The force-feedback devices offer resistance so that the volunteer feels as if he is lifting real objects…
dmunger | May 29, 2008Inspired by this post, we've decided to devote a week to the analysis of studies from the history of psychology.
Gestalt theory hit the psychology world by storm in the 1920s, and the Gestalt school's unquestioned leader (though probably not the originator of the concept) was Max Wertheimer. While many people have an intuitive understanding of the concept of "gestalt" as the essence or overall meaning of something, they may not be as aware of the Gestalt school's principles, which were laid down by Wertheimer and others in very specific and concrete ways.
What Wertheimer was reacting to was…