Reference no: EM132218693
Lab - Visual Search
I. Project
Your project is to implement the visual search paradigm in Matlab. Specifically, you will compare reaction times for a pop-out versus a conjunction search for a Treisman-style task.
Find the red "o":
• Implement the two conditions (pop-out search vs. conjunction search) with 4 set-sizes each (for example, set size = 5, 9, 13, 17). These conditions can be blocked, but you should probably alternate blocks (first do pop out, set size 5, then conjunction, set size 5, then pop-out, set size 9, etc.)
• Within blocks, make sure to randomly interleave trials with and without target. There should be an approximately equal number of trials with and without targets. Also, position the symbols randomly on the screen
• For the conjunction search, make sure to (roughly) balance the proportion of colors and of the symbols.
• Only use correct trials (subject indicated no target present when no target was present or indicated target present when it was present) for the analysis.
• Try to be as quick as possible while making sure to be right. It would be suboptimal if you had a speed/accuracy tradeoff in your data.
• The target you are looking for can be same every time - i.e. "Find the red o."
• Make sure to include at least 10 correct trials for each set size, search type (pop-out vs. conjunction) and target type (present vs. absent), for a total of 160 trials. Your results may be better with more trials (say 20 per condition)
• Pick two keys on the keyboard to indicate responses (one for target present, one for target absent).
II. Lab Report Requirements
1. Use the Matlab "plot" command to generate two figures on which a conjunction and a pop-out search can be carried out. The number of symbols should correspond to the largest set size.
2. Plot the 4 traces of the mean reaction time vs. the set size for the 4 trial types - pop-out target present, pop-out target absent, conjunction target present, and conjunction target absent.
3. Report the correlation coefficient and slopes for each of the 4 trial types.
4. Address the following questions:
- How do the reaction times for pop-out search compare to the conjunction search when the target is present?
- For both searches, what effect does the target not being present have on the reaction times?
- Is your data consistent with effect described by Treisman? If not, why do you think that might be?
Attachment:- Lab Visual Search.rar