Reaction Time Color
(Editor: Karen Brakke)
This experiment presents visual stimuli and requires the participant to make a key-press response after seeing target stimuli under different conditions. Similar to the auditory stimulus reaction time experiment, this experiment gives students the opportunity to determine whether their reaction times are reliably different for tasks that require slightly different decisions.
Each reaction time experiment uses a one-way experimental design with three levels to the independent variable, Type of Task. The three task types are:
- A simple reaction time task in which participants press a key as quickly as possible after the stimulus (in this case, a block of color) has been presented.
- A Go/NoGo reaction time task in which participants respond to one particular event (e.g., a red block of color) but ignore other events (e.g., a green block).
- A choice reaction time task in which participants respond differentially to two stimuli by pressing one key for event A and a separate key for event B.
The Task variable is manipulated within subjects, which means that each participant receives all three tasks, but to control for potential order effects across different participants, the order in which the tasks are presented is randomly determined for any one participant. The dependent variable is the time from the onset of the stimulus to the key-press reaction measured to the nearest millisecond. For choice-reaction responses, responses are also scored for correctness.
To determine whether reaction time was affected in a systematic way by the nature of the task, students can group the mean or median reaction times for a set of research participants and then perform a repeated-measures analysis of variance on the grouped data.
Students who complete both the auditory and visual versions of the Reaction Time experiment can compare results from the two experiments to see if their reaction times for the different tasks were reliably faster for one stimulus type than the other.
Data is downloadable in three formats (XML, Excel spreadsheet format, and comma delimited for statistical software packages). Figure 1 shows an excerpt from a sample Excel spreadsheet. The first six columns provide classification data (participant ID number, gender, class id, age, completion date, and time in experiment). The column labeled SIMPLE reflects the average reaction time (across trials) of the simple reaction time task. The column labeled GNG (Go/No Go) reflects the average reaction time (across trials) of the GNG task. The column labeled CHOICE reflects the average time (across trials) for the detection of a block of color.
Although all of the reaction time tasks require similar simple motor responses, they differ in the type of decision that must be made. These decisions, in turn, require different processing times because the underlying cognitive processes that are involved differ. However, several other factors can affect processing and reaction time in tasks like these. Some of them involve the type or intensity of the stimulus. Other factors stem from the participants themselves. Level of arousal or distraction, age, gender, health status, or even personality type can influence reaction times. If these factors can affect results in these simple tasks, just think how they might affect our decisions and response times in the much more complex tasks that we face every day!
Bunce, D., MacDonald, S. W. S., & Hultsch, D. F. (2004). Inconsistency in serial choice
decision and motor reaction times dissociate in younger and older adults.
Brain & Cognition, 56, 320-327.
Cooper, J. A., Sagar, H.. J., Tidswell, P., & Jordan, N. (1994). Slowed central processing
in simple and go/no-go reaction time tasks in Parkinson's disease. Brain: A Journal
of Neurology, 117, 517-529.