Visual Search Serial Search - linear increase in search time with number of distractors
Visual Search Search slope for shape singletons is flat. What does this tell us about shape and attention?
Visual Search Search slope for color singletons is flat. What does this tell us about color and attention?
Visual Search Search Slopes can be flat for targets defined by: – color – orientation – curvature – motion – depth What does this imply about these features ? What does it tell us about conjunctions of features ?
The Visual World is an Arrangement of Features Color Motion Form Depth Orientation
Pre-attentive vs. Attentive Processing Pre-attentive processing – Does the visual system register some basic features automatically (without attention) – if so, what features? – How would you know?
Pre-attentive vs. Attentive Processing Indicators of Pre-attentive processing – 1. processing precedes orienting - if you shift your attention to something or someplace because of some processing you did on the information there, you must have done that processing without attending
Pre-attentive vs. Attentive Processing Indicators of Pre-attentive processing – 2. processing done in parallel - if you can process features of several objects simultaneously, you must have done that processing without attention
Parts vs. Wholes – We see wholes, but the visual system initially sees parts (i.e. features) of objects
Parts vs. Wholes For example: We see two rectangles, but the visual pathways initially detects small lines with some orientation
Parts vs. Wholes Simple features form boundaries We see two rectangles, but the visual pathways initially detects small circles with some color
Parts vs. Wholes Conjunctions dont form boundaries We see only one rectangle (at least initially) because the boundaries of the inner one are made of conjunctions – these require attention to be perceived
Early parsing of the visual field is mediated by separate properties, not by particular combinations of properties
What does Treisman conclude from this observation? Analysis of properties and parts precedes their synthesis What is the strong prediction Treisman makes?
Illusory Conjunctions Illusory conjunction - when perceived combination of attributes was not present
Illusory Conjunctions Illusory conjunction - when perceived combination of attributes was not present Supports notion that primitive features are processed independently and then bound together to form objects This binding process is thought to require attention focused on the location of the object to be bound
Treismans Feature Integration Theory Early visual system parses scene into features represented in feature maps Attention Spotlight can be moved across an overlay of these feature maps Focused attention is required to bind features together into objects
Next Time: Attention and Consciousness Sensory information must be attended for it to be entered into awareness