PERCEPTION!

Perception•The process of integrating, organizing, and interpreting sensation

Perceptions Influenced by:

----motivation----Values----Expectations----Experience----Culture----Cognitive Style----Personality

Perception

•Selective Attention focus of

conscious awareness on a particular stimulus

•Visual Capture–tendency for vision to dominate the other senses

Perception – say it

•The process of integrating, organizing, and interpreting sensation

Gestalt Psychology

•We perceive whole objects, not isolated bits or pieces.

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the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and

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tghuhot slpeling was ipmorantt! 

Figure- Ground relationship

•organization of the visual field into object (figures) that stand out from their surroundings (ground)

•Analyzing separate information allows us to re-act to each individual object accordingly–Camouflage – when figures blend into the background

Camouflage

What is the figure, and what is the background here?

–Gestalt Psychologists focus on how we normally perceive images as groups, not isolated elements

–Several factors influence how we will group objects:-Proximity -Similarity-Continuity -Closure

Gestalt Psychology

–proximity- group nearby figures together

–similarity- Objects that are similar in appearance are more likely to be perceived as belonging in the same group

continuityThe tendency to Perceive

continuous patterns

closure-–The tendency to overlook incompleteness, and complete objects so that they fit into our mental preconceptions of what objects are supposed to look like

Constancy–perceiving objects as unchanging despite changes in retinal image

• There are three types of constancy cues:– Size Constancy– Shape Constancy– Brightness Constancy

Size Constancy•Objects closer to us will produce bigger images on our retinas, and as they move away they project a smaller image. The actual size of the object does not change

• Objects viewed from different angles will produce different shapes on our retina. Though we may change our position, the shape doesn’t change.

Shape Constancy

Brightness/Color Constancy

•We perceive objects as having a constant color, despite lighting, shading, etc.–A brick wall is still red, whether bright sunlight is on it, or darkness has made it look gray.

We perceive the white as a constant whiteness, regardless of the shadow, when in reality, it is the same gray as the gray squares...trust me.

Depth Perception• Depth Cues allow us to perceive the

world in three dimensions.–Monocular Cues depth cues that do not depend on having two eyes working in conjunction together

–Binocular Cues depth cues that depend on having two eyes working in conjunction with each other

•Relative Size•Texture Gradient •Interposition•Relative Clarity/Shadowing

•Linear Perspective•Relative motion/motion parallax

Monocular Cues

relative size

•smaller image is more distant

texture gradient

– coarse --> closefine --> distant

–(Look at the floor beneath you, and then across the room)

Interposition/ Overlap

•A closer object blocks a more distant object

relative clarity/shadowing

•hazy object seen as more distant

•Lighted objects seem closer

•Darker objects seem further away

Relative Clarity

Shadowing

• Notice the “perception” of depth changes when shading is reversed

linear perspective

•parallel lines converge with distance

Vanishing Point – where two parallel lines connect in the distance

relative motion/ Motion Parallax

•closer objects seem to move faster

•(riding in a car, trees along the road vs. houses in the distance)

•Artists use these all the time to give their work a true feeling of depth

• Trompe l'oeil

Binocular Cues

• Depth cues that require the use of both eyes

Retinal Disparity

• A binocular depth cue resulting from slightly different images produced by the separation of the retinas in the left and right eye

• Is most effective when the item is quite close to the person

Binocular Depth Cues: Finger Sausage

Convergence

• A binocular depth cue related to the tension in the eye muscles when the eyes track inward to focus on objects close to the viewer

• The more tension in the eye muscle, the closer the object is

• Works best at close distances

–(Retinal) Binocular disparity•images from the two eyes differ

•closer the object, the larger the disparity

•(Hold a pencil in front of you, close one eye, then close the other eye- you get two different images)

Motion•Eye muscle activity•Changing retinal image•Contrast of the moving object and its stationary background

•All combine to bring us the perception of motion

Motion•Stroboscopic Motion- timed flashing lights or moving pictures that give the illusion of movement

Factors That Influence Perceptual Interpretations

•Perceptual Set–The tendency to perceive a person or a situation in a particular way due to our past experiences with similar persons or situations

Perpetual Set - UFO

Perceptual Illusions

•When our normal, automatic perception processes guide us to the wrong conclusions

Muller- Lyer Illusion• Which area is longer?

How about these ?

Which monster and line segment is larger?

Subliminal Perception

•Thresholds imply that there must be stimulus below and beyond our current levels of detection. Can human behavior be influenced by stimulus that is below or beyond our level of awareness?

Extrasensory Perception

•Some people claim to have extra powers of perception, or the ability to respond to an unknown event that is not presented to any of the known senses.

•Parapsychology

Cover one eye with a sunglass lens…