Posener Paradigm

An important paradigm for studying visual attention in the last two decades has been the Posner cueing
paradigm (Posner, 1980). In this paradigm, a target can appear in one of two locations, and the observer reports
whether the target is present (yes/no). Prior to the presentation of the stimulus, a cue (precue) indicates the
probable location of the target (given that the target is present) with some validity (e.g., 80% of the trials). Those
trials in which the cue correctly indicates the location of the target are known as the valid cue trials, whereas the
trials in which the cue incorrectly indicates the location of the target are called the invalid cue trials. A classical result
is that performance (measured with response times or target detection accuracy) is better in the valid cue trials
versus the invalid cue trials.

Stroop Paradigm

The Stroop Effect is an interesting phenomenon. Classically, this is demonstrated with colors. A person is presented with a series of colors written in different colored type. So, you might see the word BLUE in red type, in black, in blue, etc. The person is asked to say the color of the type aloud. A series of these words are presented. If the word BLUE is presented in red type, the effect is such that the person seeing the word almost invariably takes longer to say the word RED than s/he does if the word appears in blue type.