According to the feature integration theory, simple preattentive stimulus attributes (color, shape, etc.) guide our scanning of the environment, with higher-order processes coordinating the binding of features and, ultimately, conscious perception and selection.

Feature Integration Theory

The binding problem raises the question of how the brain knows that a particular set of features combine to define a single object, considering that these different features are processed in different regions of the brain. This is answered by the feature integration theory.
- Feature Integration Theory

Johns Hopkins University

Conjunction search involves searching for an item on the basis of two or more features (ie. size and color) that together distinguish the target from distracters that may share some of the same attributes. "Where's Waldo" is a good example before you are searching for a 1. boy 2. specific outfit.

Conjunction Search

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

A bottom-up process, broadly speaking, is a process in which lower-order mechanisms, like sensory inputs, trigger additional processing by higher-order systems. Conjunction searches run much faster when you can direct your attention to a single basic attribute of the stimuli to be scanned rather than using systematic voluntary steering of the attentional spotlight using all attributes simultaneously.

Learn Before

Related

Learn After