How quickly can you respond to something? If you are expecting to see a green light, but
Question:
How quickly can you respond to something? 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. In 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.
Debriefing:
What methods did we employ in this experiment?
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. Detection is not instantaneous: 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.
What do we predict participants will do? Why?
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.
How robust is this effect? Are there limits to this effect?
Even on the most accurate equipments, it is unlikely that people will respond much faster than about 200 ms due to a combination of cognitive and biomechanical constraints.
Results:
The plot shows your response time in milliseconds for each trial. The expected result is that while you might improve slightly with practice, your RT will be more than 200 ms.
Trial Number | RT (ms) |
1 | 350.616 |
2 | 308.754 |
3 | 300.720 |
4 | 296.985 |
5 | 296.378 |
6 | 296.371 |
7 | 296.393 |
8 | 296.271 |
9 | 296.245 |
10 | 296.637 |
11 | 297.116 |
12 | 296.769 |
13 | 296.454 |
14 | 296.899 |
15 | 297.295 |
16 | 297.903 |
17 | 297.830 |
18 | 297.778 |
19 | 298.206 |
20 | 295.560 |
Questions:
1. Explain why this CogLab exercise is termed “detection”, and provide a guess why it is “simple” and not complex.
2. Here is an issue to consider concerning internal validity. Sometimes a participant in this lab has a response time that is less than 100 milliseconds. How might you explain such very short responses? Suppose another experiment had participants say the word “now” as soon as they detected the green circle, and that the response times were between 100 and 200 milliseconds. What would you conclude about the cognitive tasks involved in these two versions of simple detection?
Finance Applications and Theory
ISBN: 978-0077861681
3rd edition
Authors: Marcia Cornett, Troy Adair