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PerceptionPerception

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PerceptionPerception

The process of selecting, organizing, and The process of selecting, organizing, and interpreting sensory information, which enables interpreting sensory information, which enables us to recognize meaningful objects and events.us to recognize meaningful objects and events.

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Selective AttentionSelective Attention

Perceptions about objects change from moment to Perceptions about objects change from moment to moment. We can only focus on limited aspects of moment. We can only focus on limited aspects of

sensory input at any given timesensory input at any given time

e.g. : e.g. : ““Cocktail Party EffectCocktail Party Effect””

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Perceptual IllusionsPerceptual Illusions

Illusions provide good examples in Illusions provide good examples in understanding how perception is understanding how perception is

organized. Studying faulty perception is organized. Studying faulty perception is as important as studying other as important as studying other

perceptual phenomena.perceptual phenomena.

Line AB is longer than line BC.

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Tall ArchTall Arch

In this picture, In this picture, the vertical the vertical

dimension of the dimension of the arch looks arch looks

longer than the longer than the horizontal horizontal

dimension. dimension. However, both However, both

are equal.are equal.

Rick F

riedman/ B

lack Star

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Perceptual OrganizationPerceptual Organization

How do we form meaningful How do we form meaningful perceptions from sensory information?perceptions from sensory information?

We organize it. Gestalt psychologists We organize it. Gestalt psychologists showed that a figure formed a showed that a figure formed a ““wholewhole””

different than its surroundings.different than its surroundings.

called a called a ““gestaltgestalt””

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Organization of the visual field into objects Organization of the visual field into objects (figures) that stand out from their (figures) that stand out from their

surroundings (ground).surroundings (ground).

Form PerceptionForm Perception

Tim

e Savings S

uggestion, © 2003 R

oger Sheperd.

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GroupingGrouping

After distinguishing the figure from the After distinguishing the figure from the ground, our perception needs to organize ground, our perception needs to organize the figure into a meaningful form using the figure into a meaningful form using

grouping rules.grouping rules.

Our perceptions are a combination Our perceptions are a combination of sensory (bottom-up) and cognitive of sensory (bottom-up) and cognitive (top-down) processes.(top-down) processes.

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Perception in BrainPerception in Brain

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Perceptual InterpretationPerceptual Interpretation

Immanuel Kant (1724-1804) maintained that Immanuel Kant (1724-1804) maintained that knowledge comes from our inborn ways of knowledge comes from our inborn ways of

organizing sensory experiences.organizing sensory experiences.

John Locke (1632-1704) argued that we learn John Locke (1632-1704) argued that we learn to perceive the world through our to perceive the world through our

experiences.experiences.

How important is experience in shaping ourperceptual interpretation?

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Kittens raised Kittens raised without exposure without exposure to horizontal lines to horizontal lines later had difficulty later had difficulty

perceiving perceiving horizontal bars.horizontal bars.

Blakemore & Cooper (1970)

Sensory DeprivationSensory Deprivation

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(a) Loch ness monster or a tree trunk; (b) Flying

saucers or clouds?

Perceptual SetPerceptual Set

Other examples of perceptual set.Other examples of perceptual set.

Frank Searle, photo Adam

s/ Corbis-Sygm

a

Dick R

uhl

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To an East African, the woman sitting is balancing a metal box on her head, while the family is sitting

under a tree.

Cultural ContextCultural Context

Context instilled by culture also alters Context instilled by culture also alters perception. perception.

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Perception RevisitedPerception Revisited

Is perception innate or acquired? Is perception innate or acquired?

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Human Factors & Human Factors & MisperceptionsMisperceptions

Understanding human factors enables us to Understanding human factors enables us to design equipment to prevent disasters.design equipment to prevent disasters.

Two-thirds of airline crashes caused by human error are largely due to errors of perception.

The following factor(s) affect our The following factor(s) affect our detection of weak signals:detection of weak signals:

a.a. motivationmotivation

b.b. fatiguefatigue

c.c. expectationsexpectations

d.d. all of the aboveall of the above

e.e. b & c but not ab & c but not a17

With respect to sensation and perception, With respect to sensation and perception, it is fair to say that :it is fair to say that :

a.a. experience plays no roleexperience plays no role

b.b. perception does not appear to involve perception does not appear to involve any inborn perceptual capacitiesany inborn perceptual capacities

c.c. humans experience external stimuli as humans experience external stimuli as they are with little processing by the they are with little processing by the brainbrain

d.d. none of the abovenone of the above

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