Reaction Time Color Author: John E. Williams, University of Mississippi Editor: Karen Brakke, Spelman College Introduction Although much of the time we think that our mental processes are simple and immediate, the reality is that different mental tasks require varied cognitive processes that may take different amounts of time. In this experiment, participants view visual stimuli and make a key-press response based on different tasks. Participants see target stimuli in three different conditions, as described below. Similar to the auditory stimulus reaction time experiment, this experiment shows that reaction times can be reliably different for tasks that require slightly different decisions. Design This reaction time experiment uses an experimental design with three different tasks constituting levels of a single independent variable. The three task types are: 1. A simple reaction time task in which participants press a key as quickly as possible after the stimulus, a block of color, has been presented. 2. A Go/No-Go reaction time task in which participants respond to the appearance of one particular stimulus (e.g., a red block of color) but ignore others (e.g., a green block). 3. A choice reaction time task in which participants respond differentially to two stimuli by pressing one key for stimulus A and a separate key for stimulus 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 each participant. The dependent variable is the time from the onset of the stimulus to the key-press reaction measured. Time is measured to the nearest millisecond