Perception

Agenda 1. Bell Ringer: Reading Quiz 2. Lecture: Perception and Illusion (20) 3. Inattentional Blindness Activity (10) - Giving Directions Clip (5) 4. Perceptual Illusions (10) 5. Handout 6-4 (15)

Perception is the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Types of Perceptions Form Perception – we must perceive a figure from its ground Depth Perception – transform 2D into 3D Motion Perception – brain computes motion as images move across retina Perceptual Interpretation – how we recognize an object

Perception Selective Attention : the focusing of conscious awareness on a particular stimulus.

Cocktail party effect: Is the ability to attend selectively to one voice among many.

http://www. youtube. com/watch http://www.youtube.com/watch?v=vJG698U2Mvo&safety_mode=true&persist_safety_mode=1&safe=active

Inattentional Blindness Inability to see an object or a person in our midst. Simmons and Chabris (1999) showed that 1/2 of the observers failed to see the gorilla suited assistant in a ball passing game

Change Blindness A form of inattentional blindness. When you do not notice when something changes because you are so focused on something else.

Two-thirds of individuals giving directions failed to notice a change in the individual asking directions.

Change Blindness http://www.youtube.com/watch?v=vBPG_OBgTWg&safety_mode=true&persist_safety_mode=1&safe=active Stop at 2:20

Perceptual Illusions Muller-Lyer (1889) Which line is longer?

Perceptual Illusions

Tall Arch The vertical dimension of the arch looks longer than the horizontal dimension. However, both are the same

Perceptual Illusions

http://www. youtube. com/watch http://www.youtube.com/watch?v=hCV2Ba5wrcs&safety_mode=true&persist_safety_mode=1&safe=active

The Ames room is designed to demonstrate the size-distance illusion.

Perceptual Illusions Helen Ross 1975

Perceptual Illusions The figure on the right gives the illusion of a blue hazy “worm” when it is nothing more else but blue lines indenticial to the figure on the left.

Perceptual Illusions

Perceptual Organization Visual Capture – the tendency for vision to dominate the other senses. Gestalt – an organized whole. The tendency to integrate pieces of information into meaningful wholes. Think puzzles

Gestalt psychologists are fond of the saying that in perception the whole may exceed the sum of its parts. Bottom-up and top-down processing

Perceptual Organization Necker Cube

Form Perception Figure-Ground – the organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

Example of figure - ground At a party, the person you are talking to is the FIGURE and all the other people at the party are part of the GROUND.

Figure – Ground

Figure-Ground

Figure Ground

Form Perception Grouping – the perceptual tendency to organize stimuli into coherent groups.

Grouping Principles Proximity – group nearby figures together Similarities – group figures that are similar Continuity – perceive continuous patterns Connectedness – spots, lines, and areas are seen as a unit when connected Closure – fill in the gaps

Grouping Principles

Closure

Grouping Principles – they can lead up astray.