2/19/01
Note: These due dates are subject to change. If there
is a conflict between what you see here and what the instructor says in
class, go with what is given in class.
Last updated: 1/18/01
The experiment is based on a previous study by Levy et al., 1983. That article is on reserve at the library and you should read it to help you understand the study. We will measure left-right asymmetries in the viewing of emotional faces. Many previous studies have shown that when subjects are shown a pair of chimeric faces (faces with one side smiling and the other side showing a neutral expression), and asked to say which face appears happier, they will choose the chimera with the smile to their (the viewer’s) left. This is most likely due to the fact that, in right-handers, the right side of the brain is dominant for the perception of faces and emotional expression. So when asked to judge the emotional expression of faces, the right hemisphere becomes more active. This causes a bias in attention to the left side of space. Thus, subjects pay more attention to the left side of the photograph. (A more detailed description of the task can be found in the reserve article by Levy et al., which was the first one to use these photographs).
The purpose of our study is to determine whether this leftward bias can be influenced by the instructions given to the subjects. Half of the subjects will be given the traditional instructions, which emphasize that they should not think about it too much. The other half will be told to think about it carefully, and to examine every detail of the faces. (The exact instructions are on the Web). Based on previous results, we might expect that people who pay close attention to the details will be more likely to use their left hemisphere, and will therefore show a reduced leftward bias (i.e. their LQ will be more positive). However, when we previously tried to test this hypothesis in SRM II, we did not find a significant difference between the groups given the different instructions. One possible reason for this lack of significance is that, over time, the subjects in the detailed condition got tired of paying attention to the details and started to just go with their first impression. So if we had looked at the scores from the first half of the test, we would have found a difference between the two groups, but we wouldn't if we looked as the scores from the second half of the test. So, the specific purpose of our study is to answer the question: "Do differences in instructions make a difference in a subject's laterality quotient during the first half of the test, but not during the second half?"
We will only analyze data from right-handed subjects. The task will be scored by counting, for each subject, the number of times they chose the face with the smile to their (the viewer’s) left, and the number of times they chose the face with the smile to their right. A “laterality quotient” will be computed for each half of the test by subtracting the number of smile-left choices from the number of smile-right, and dividing by the total: (R-L)/18. Thus, a negative number indicates a leftward bias, and a positive number indicates a rightward bias.
To see the data, click here.
To see a manuscript of the project from SRM II, click here.
To see the two instructions given, click here.
To see the second answer sheet, click here.
due: Wed. 1/24
Homework assignment #2 will be a write-up (using APA style) of an
experiment that we will conduct and analyze in class. You must write
the Method and Results sections. It it Experiment #22 in the Superlab
manual. The original article by Meyer and Schvaneveldt is on reserve
at the library to help you understand the study.
To see the data, click here.
due: Mon. Feb. 5
Due: Wed. Feb. 14
Homework assignment #4 will be
a write-up (using APA style) of an experiment that we will conduct and
analyze in class. You must write the Method and Results sections and include
a Figure (and Figure Caption page). It is Experiment #17 in the SuperLab
manual. The original article by Rips et al. is on reserve at the library
to help you understand the study. You only need to read about Experiment
1 in that article.
The purpose of the study is to determine
whether people are faster to confirm a sentence in which the subject and
predicate are separated by only 1 level (e.g. "A robin is a bird.")compared
to when they are separated by 2 levels (e.g. "A robin is an animal.").
In addition, we will seek to determine whether the effect of level might
differ for different types of categories (e.g. birds vs. mammals).
due: Wed. Feb. 21
Homework assignment #5 will be a write-up (using APA style) of an experiment that we will conduct and analyze in class. You must write the Method and Results sections and include a Figure (and Figure Caption page). It is Experiment #6 in the SuperLab manual. The original article by Treisman is on reserve at the library to help you understand the study. You only need to read about Experiment 1 in that article.
This project will examine how people search for a visual target amonst a group of non-targets (distractors). We will compare two types of search - feature and conjunctive (these terms are defined in the Treisman article). The question we will ask is whether the effect of number of distractors on RT is different for the two types of search, and whether it is different for "yes" and "no" responses.
If you're not happy with the score you get, you may re-write it and
hand it it again. However, the maximum score you can get on the re-write
will be 8 out of 10.
due: Monday, Feb. 26 (if you're not meeting with me that day you can bring it by my office or leave it in my mail box).
re-write due Friday, 3/9.