Review
bookzen.blogspot.com
Product Description
The brain is a fearsomely complex information-processing environment--one that often eludes our ability to understand it. At any given time, the brain is collecting, filtering, and analyzing information and, in response, performing countless intricate processes, some of which are automatic, some voluntary, some conscious, and some unconscious.
Cognitive neuroscience is one of the ways we have to understand the workings of our minds. It's the study of the brain biology behind our mental functions: a collection of methods--like brain scanning and computational modeling--combined with a way of looking at psychological phenomena and discovering where, why, and how the brain makes them happen.
Want to know more? Mind Hacks is a collection of probes into the moment-by-moment works of the brain. Using cognitive neuroscience, these experiments, tricks, and tips related to vision, motor skills, attention, cognition, subliminal perception, and more throw light on how the human brain works. Each hack examines specific operations of the brain. By seeing how the brain responds, we pick up clues about the architecture and design of the brain, learning a little bit more about how the brain is put together.
Mind Hacks begins your exploration of the mind with a look inside the brain itself, using hacks such as "Transcranial Magnetic Stimulation: Turn On and Off Bits of the Brain" and "Tour the Cortex and the Four Lobes." Also among the 100 hacks in this book, you'll find:
- Release Eye Fixations for Faster Reactions
- See Movement When All is Still
- Feel the Presence and Loss of Attention
- Detect Sounds on the Margins of Certainty
- Mold Your Body Schema
- Test Your Handedness
- See a Person in Moving Lights
- Make Events Understandable as Cause-and-Effect
- Boost Memory by Using Context
- Understand Detail and the Limits of Attention
From the Author
Each Hack describes a phenomenon and gives an explanation of the psychology and neuroscience behind it. The demonstration will either make you go "wow" or it will make you go "I always noticed that - but I thought it was just me". Did you know that you spend 90 minutes of your waking day functionally blind (because visual input is cut off when your eyes move)? That you can improve your muscle strength by mental exercise alone? That preventing someone talking to themselves can stop them being able to combine information from different senses? Would you like to know why you're good with faces but not with names? Why you have a favourite coffee cup or why it is easier to listen to someone if you are wearing your glasses? The book lets you understand why these things happens, what they mean about our brain, and how they connect to the rest of our everyday lives. We had great fun writing the book, and some fantastic contributors. It is ram-packed full of tit-bits, information-nuggets, links and references for following things up. Come and visit us at mindhacks.com to get a taster.
- Tom & Matt
About the Author
Tom Stafford has a PhD in Cognitive Neuroscience and is currently a research associate in the Department of Psychology, University of Sheffield. He is also an associate editor of the Psychologist magazine and has previously worked as a freelance writer and researcher for the BBC.
Matt Webb's background is in new media. His freelance activities include an IM interface to Google, which predated the Google API and is included in O Reilly s Google Hacks. He launched a project to find the Web's favorite color that was featured on BBC News Online and national newspapers in the UK. His current job in R&D at the BBC involves these kinds of projects internally, and gives him experience at addressing abstract social and technological ideas to mixed audiences. He was a popular speaker at O Reilly's Emerging Technology Conference in 2004.
Excerpted from Mind Hacks by Tom Stafford, Matt Webb. Copyright © 2004. Reprinted by permission. All rights reserved.
More intense signals cause faster reaction times, but there are diminishing returns: as a stimulus grows in intensity, eventually the reaction speed can’t get any better. The formula that relates intensity and reaction speed is Pieron’s Law.
It’s a common illusion that if you are in a hurry for the elevator you can make it come quicker by pressing the button harder. Or more often. Or all the buttons at once. It somehow feels as if it ought to work, although of course we know it doesn’t. Either the elevator has heard you, or it hasn’t. How loud you call doesn’t make any difference to how long it’ll take to arrive.
But then elevators aren’t like people. People do respond quicker to more stimulation, even on the most fundamental level. We press the brake quicker for brighter stoplights, jump higher at louder bangs. And it’s because we all do this that we all fall so easily into thinking that things, including elevators, should behave the same way.
In Action
Give someone this simple task: she must sit in front of a screen and press a button as quickly as she can as soon as she sees a light flash on. If people were like elevators, the time it takes to press the button wouldn’t be affected by the brightness of the light or the number of lights.
But people aren’t like elevators and we respond quicker to brighter lights; in fact, the relationship between the physical intensity of the light and the average speed of response follows a precise mathematical form. This form is captured by an equation called Pieron’s Law. Pieron’s Law says that the time to respond to a stimulus is related to the stimulus intensity by the formula:
Reaction Time ≈ R0 + kI-â
Reaction Time is the time between the stimulus appearing and you responding. I is the physical intensity of the signal. R0 is the minimum time for any response, the asymptotic value representing all the components of the reaction time that don’t vary, such as the time for light to reach your eye. k and â are constants that vary depending on the exact setup and the particular person involved. But whatever the setup and whoever the person, graphically the equation looks like Figure 1-2.
How It Works
In fact, Pieron’s Law holds for the brightness of light, the loudness of sound, and even the strength of taste.1 It says something fundamental about howwe process signals and make decisions—the physical nature of a stimulus carries through the whole system to affect the nature of the response. We are not binary systems! The actual number of photons of light or the amplitude of the sound waves that triggers us to respond influences how we respond. In fact, as well as affecting response time, the physical intensity of the stimulus also affects response force as well (e.g., how hard we press the button).
A consequence of the form of Pieron’s Law is that increases in speed are easy for low-intensity stimuli and get harder as the stimulus gains more intensity. It follows a log scale, like a lot of things in psychophysics. The converse is also true: for quick reaction times, it’s easier to slow people down than to speed them up.
Pieron’s Law probably results because of the fundamental way the decisions have to be made with uncertain information. Although it might be clear to you that the light is either there or not, that’s only because your brain has done the work of removing the uncertainty for you. And on a neural level, everything is uncertain because neural signals always have noise in them.
So as you wait for light to appear, your neuronal decision-making hardware is inspecting noisy inputs and trying to decide if there is enough evidence to say "Yes, it’s there!" Looking at it like this, your response time is the time to collect enough neural evidence that something has really appeared. This is why Pieron’s Law applies; more intense stimuli provide more evidence, and the way in which they provide more evidence results in the equation shown earlier.
To see why, think of it like this: Pieron’s Law is a way of saying that the response time improves but at a decreasing rate, as the intensity (i.e., the rate at which evidence accumulates) increases. Try this analogy: stimulusintensity is your daily wage and making a response is buying a $900 holiday. If you get paid $10 a day, it’ll take 90 days to get the money for the holiday. If you get a raise of $5, you could afford the holiday in 60 days—30 days sooner. If you got two $5 raises, you’d be able to afford the holiday in 45 days—only 15 days sooner than how long it would take with just one $5 raise. The time until you can afford a holiday gets shorter as your wage goes up, but it gets shorter more slowly, and if you do the math it turns out to be an example of Pieron’s Law.
