Visual Search Test — Free Feature vs Conjunction Search Efficiency Task

The visual search task is the classic paradigm behind Treisman and Gelade's 1980 feature integration theory. When a target differs by a single feature such as color, it pops out no matter how many distractors surround it (feature search); when it can only be told apart by combining color and shape (conjunction search), you have to scan items one by one and time grows with their number. This test uses that difference to measure the efficiency of visual attention.

A red T is always somewhere on the screen; tap it as soon as you find it. In the first block (feature search) it hides among blue Ts; in the second block (conjunction search) it hides among a mix of red Ls and blue Ts. Each block has 4 practice trials followed by 36 main trials — 12 each at set sizes of 4, 8 and 16 items — with a 10-second limit per trial.

How much search time grows per additional item (the slope) reflects the speed at which attention moves from one location to the next, which is why it serves as an index of visual attention efficiency distinct from simple reaction speed.

The key measure is the search slope in ms per item: a least-squares line is fitted to reaction times at set sizes 4, 8 and 16 to find how many extra milliseconds each item costs. In feature search, an absolute slope under 10 ms/item is described as normal pop-out; conjunction slopes are labeled very low under 15, typical under 40, high under 80 and very high at 80 or more.

The intercept shown next to the slope is your baseline speed independent of set size, and accuracy is the proportion of trials where your first tap landed on the red T. Wrong taps and 10-second timeouts are also listed. The overall score is 0-100, weighting 70% on the conjunction slope (scaled so that 80 ms/item equals 0 points) and 30% on accuracy.

Because you respond by tapping, the time it takes your finger to reach the target is included in reaction time, and spacing between items changes with screen size. It is therefore more meaningful to follow the trend of your slope across repeated measurements on the same device than to compare with others, and speeding up over the first attempt or two through practice is normal.

The conjunction search slope is sensitive to fatigue and lost sleep: after a poor night, time per item rises noticeably. Caffeine speeds baseline responding but can add hasty wrong taps, and a gradual increase in slope with age is a natural change. Difficulty with eyesight or color discrimination, a dim screen and small letters also affect results.

Soundary saves your results and shows the change from your previous test. Repeating every one to two weeks on the same device at a similar brightness and time of day, and following the trend in conjunction slope, helps you tell condition-related fluctuation from steady change. This is a self-check, not a diagnostic tool.

If your conjunction slope stays very high even after you are rested and familiar with the task, wrong taps and timeouts keep recurring, and finding objects or locating information on a screen has become noticeably slower in daily life, consider an eye examination together with a cognitive assessment from a professional.