The Visual Search Task is a widely used paradigm for studying selective attention and visual scene analysis. Participants view displays of orange letters and must detect the presence or absence of a target: an upright letter T. Distractors are rotated T's (90° or 270°) and L's (0°, 90°, 180°, or 270°), creating a conjunctive search condition that requires serial visual scanning.

The defining measure of visual search efficiency is the search slope: the increase in reaction time (RT) per additional item in the display. Steep slopes (> ~10 ms/item) indicate serial, attention-demanding search; shallow slopes (< ~5 ms/item) indicate parallel, preattentive detection. Target-absent slopes are typically twice as steep as target-present slopes for conjunctive searches, because participants must check all items before concluding the target is absent.

This implementation uses four set sizes (5, 10, 15, 20) with equal numbers of target-present and target-absent trials. Item positions are randomly generated on each trial using a grid-jitter algorithm, and distractor identities (T vs. L) are assigned randomly. All stimulus parameters are configurable in the Open Lab study builder.