I suggest that you take a look at the Reaction Time (RT) Color experiment at the Online Psychological Laboratory (OPL) at http://opl.apa.org . If you want to collect data from your class, register your class on the website (see "Register" on the menu bar near the top of the page). Your class' data will then become publicly available via the Data page on the website (see "Data" on the menu bar). If you just want data that other classes have contributed, one can just go to the data page and decide how much data one wants to download -- I suggest a couple of hundred participants for reasons I provide below.
For background on the RT-Color experiment see: http://opl.apa.org/Experiments/About/AboutReactionTimeColor.aspx However, the three RT tasks that are used were originally developed by Franciscus Donders back in in the 1850s and published at time in, I believe, French and an English translation was published in 1969 in the journal Acta Psychologica (in Pubmed.gov, this is the citation http://www.ncbi.nlm.nih.gov/pubmed/5811531 ). The RT tasks are: (1) Simple RT: press a key on a keyboard when a colored square appears on the screen (2) Go-No Go RT: press a key when a red square appears, withhold response for any other color (3) Choice RT: press one key for red, another key for blue The dependent variable is RT in seconds which should be converted into milliseconds. There are a minimum of 20 trials for each task and the mean RT across the 20 trials is used to reflect a person's performance on the task. Thus, we have a one-way, three level within-subject design. It is expected that mean RT (across subjects) will increase as a function of task complexity, so: Mean RT(simple) < mean RT(Go-No Go) < mean RT(choice) Now, for tasks (2) and (3) error trials can easily be specified, so 20 trials of correct responses are required (that is, a person may only experience 20 trials on a task if the responses are all correct, more trials if errors are made). The Simple RT task doesn't have an "error responses", probably because it is assumed that participants should always be able to do such a task without error. However, there are some people who have unusually long mean simple RT that simply can't be right. It is unclear what is going on but some people just have a hard time with the simple RT task (Note: according to Donders' theory and most results, a simple RT should not be greater than the Go-No Go RT or the Choice RT). This is a good discussion point about what do with outliers or extreme values that have a big influence on the mean. Median RT and the minimum RT values typically follow the predicted results as do trimmed means and other robust measures of location (such as those used in SPSS Examine procedure). One way to deal with this problem is to exclude subjects/participants with simple RT > 1000 ms but one should make sure that they understand the patterns of RT across all tasks (there usually are outliers there as well; what do about them -- just ignore them?). With small samples, like with a small class, the ANOVA results and multiple comparisons may or may not be significant because of a lack of statistical power. Excluding subjects will make the situation worse. Getting additional subjects will provide sufficient power producing a significant repeated measures ANOVA and multiple comparison results (i.e., all three task means should be significantly different from each other). A better solution to the situation is alter the simple RT task a little, say, if a person's RT on a trial is greater than 1 second, they have to repeat the trial. This would then produce 20 "error free" trials comparable to the other tasks. -Mike Palij New York University [email protected] ------------------------ Original Message On Sun, 06 Mar 2011 10:08:48 -0800, Michelle Everson wrote: >Hello, >First, I apologize for the cross-posting. > >I'm looking for a quick in-class activity I can do (in an intermediate >statistics course) in order to introduce my students to the repeated- >measures (or one-way within-subjects) ANOVA. I have a relatively small class >(21 students) and we meet in a computer lab. I was hoping to do something in >class that would yield some data that we can then explore and analyze right >on the spot. Does anyone have any good suggestions? One thought I had was >something where students could work through puzzles of some kind on the >computer (where the DV would be the amount of time taken to complete the >puzzle). Ideally, I wanted at least three different conditions for them to >work through, but we could have just two. I'm just not sure if there is a >website out there that might give me what I need to pull this off (by >Wednesday!). Also, I have some students in class for whom English is a >second language, so I want to avoid tasks that could be very challenging or >frustrating for those students (e.g., I was initially thinking of word >puzzle activities like Boggle, but I think that would be too much for some >students). > >Thank you so much for any ideas you might have to share. --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=9208 or send a blank email to leave-9208-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
