What methods did we employ in this experiment?
On each trial, circles and squares of various colors were shown on the screen. Your task was to determine whether or not there was a green circle among the shapes.
For the first set of trials (feature search), the other distractor shapes were all blue. For the other set of trials (conjunctive search), some of the other shapes were blue circles and others were green squares.
The independent variables in this experiment were (1) the type of search (feature or conjunctive), the number of distractor shapes, and whether the target is present or absent. The dependent variable was the response time between the appearance of the stimuli and your response.
What do we predict participants will do? Why?
The results are broken down by the type of search and whether the target was present or absent. For feature searches, the response time should not change as the number of distractor shapes increases. This should be true both for when the target is in the frame (“Feature, Present”) and for when the target is not in the frame (“Feature, Absent”). For conjunctive searches, the response time should increase as the number of distractor shapes increases. For the conjunctive searches, the rate of increase should be faster when no target is in the frame (“Conjunction, Absent”) than when the target is in the frame (“Conjunction, Present”).
The pattern of results for the conjunctive searches is consistent with the idea that attentional focus is moved around from shape to shape. Each focus on a shape takes time to judge whether it is the target or not. This explains why search time increases with the number of distractor shapes. If the target is found, the search stops. On the other hand, if the target is not present, you must search all the shapes. This explains why the target-absent trials take longer than the target-present trials.
The pattern of results for the feature searches suggests that there is little need for movement of attention from shape to shape. Instead, the properties of the target are able to quickly draw attention to the target (e.g., because it is the only green item).
How robust is this effect? Are there limits to this effect?
The pattern of results is usually very robust.
Student Information
Data Summary for MindTap2765-3
Date Completed 2021-09-29 22:44:11 Eastern Daylight Time
Time Spent On Lab 12 minutes
Mean Detection Time
This experiment explores aspects of attention in a visual-search task. You will complete the lab in Mindtap and then share your results and impressions with your classmates. Answer the following questions:
What were your results and were you surprised by them? If so, why? Support your lab reflection with chapter or other credible source information.
Consider everyday situations where visual searches is an occupational necessity. What job(s) can you think of that would require this skill? Are the searches for your example complex or simple to do and why? (For example (you cannot use this one), a police officer may have to visually search a crowd for a suspect)
Num. Distractors Feature Present Feature Absent Conjunction Present Conjunction Absent
4 1937.600 869.400 552.200 665.200
16 683.200 932.400 593.600 513.000
32 972.800 814.800 620.000 513.200
64 1064.200 1311.000 544.600 857.200
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