CogLab Simple Detection Chp 1 Lab 2

Question 1

Background

Answer 1

• If you are expecting to see a green light, but don’t know exactly when it will be turned on, how much time elapses between the light turning green and your response?
• This is sometimes called simple detection because the only decision you are making is whether the stimulus has appeared. I
• n more complex tasks, you might need to press one button for Stimulus A and a second button for Stimulus B.
• In that task, there is an additional decision: Not only must you decide that a stimulus has been shown, but you must also decide which of two responses is appropriate.

Question 2

Lab Insructions

Answer 2

In this lab, a fixation point is shown and then disappears. After a random amount of time, a green circle appears. Your task is to make a response as quickly as you can when you detect the green circle.

At the end of the experiment, you will be asked if you want to save your data to a set of global data.

Question 3

What methods did we employ in this experiment?

Answer 3

• On each trial of the experiment, a dot appeared after a variable amount of time and you were asked to respond as soon as you detected it.
• This task is not really a proper experiment; rather, it is a way of measuring a basic ability.
• it takes time for the information registered by your eyes to be converted and sent on to the brain.
• Then, it takes additional time, perhaps the largest proportion, for you to decide that the information means that a green circle was seen and therefore you should press the button.
• Then, it takes additional time for that message to go to your finger. Finally, there is the time it takes to actually move your finger.

Question 4

What do we predict participants will do? Why?

Answer 4

• The graph below plots the time you took to detect the circle as a function of the trial number. Most people should have a response time between about 200 and 300 ms (although this may vary depending on your computer/tablet).
• In general, response times will be faster on computers with keyboards than on tablets due to the way in which these devices process key presses and taps.

Question 5

How robust is this effect? Are there limits to this effect?

Answer 5

Even on the most accurate equipment, it is unlikely that people will respond much faster than about 200 ms due to a combination of cognitive and biomechanical constraints.