Chapter 7Perceiving the World

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A Changing Picture

Influences on Perception.

What would guide your understanding / perception of a sensation?

Essay in your Journal Perceptual Sets

Personal Needs

Mood, Attitude, and Values

Collective Perceptions

Give personal examples of each…

1.

Perceptual Set

- Mental sets or Drivers- Past experiences guide our perceptions- We get ready to perceive an event

2.

Personal needs (define want and need)- The more you want or need something the more strongly you

perceive things that satisfy that need- Hunger, thirst… Others?- Motivation for focus- Non-bordomize/ bordomize

3. Mood, attitude, and values

-perception can be affected by feelings about the class, school, work, people…

-attitude affect more deeply and permanently the way view the world

Have fun/ play

Make a their day

Be there

Choose your attitude.

(Fish video)

-values

we respond to the kind of environment that agrees with our values… such as…(give examples)

Assignment

Have fun/ Play

Make their day

Be there/ right there

Choose your attitude.

In your journal document your “Fish Story”

4. Collective perception ( read pages 200 -201)

- perception can be influenced by what others say they perceive

- Collective ideas are trusted more than a persons individual perception. (Asch’s conformity study..see video)

Anger Eyes by Jane Elliot In your journals answer the following questions.

1. Appraise the meaning of “Racism” as applied by Jane Elliot in the videos, “A Class Divided” and “Anger Eyes”.

2. Evaluate your answer above as a product of the psychological term…”Perception” using the four categories from your notes.

Perception: Mental process of organizing sensations into meaningful patterns

Size Constancy: Perceived size of an object remains constant, DESPITE changes in its retinal image

Native Perception: A perceptual experience based on innate processes

Empirical Perception: A perception strongly influenced by prior experience

Shape Constancy: The perceived shape of an object is unaffected by changes in its retinal image

Perception: Some Key Terms

Figure 7.10 The eyes must converge, or turn in toward the nose, to focus close objects.

Figure 7.25 Context alters the meaning of the middle figure.

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A Changing Picture

Brightness Constancy: Apparent brightness of an object stays the same under changing lighting conditions

Figure-Ground Organization: Part of a stimulus stands out as a figure (object) against a less prominent background (ground)

Reversible Figure: Figure and ground can be reversed Illusory Figure: Implied shape not bounded by an edge or an outline Impossible Figure: Figure that cannot be organized into a stable

perception

Perceptual Grouping

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Defining Perception

An active process The brain pieces

together bits of sensory information in order to form orderly impressions or pictures

Gestalt

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Gestalt Principle #1: Proximity

“Meaningful wholes seem to precede parts and properties, as the Gestalt psychologists emphasized years ago.” –Anne Triesman

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Gestalt Principle # 2: Similarity

When similar and dissimilar objects are mingled together, we see the similar objects as groups

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Gestalt Principle # 3: Continuity

We tend to see continuous patterns, not disrupted ones

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Gestalt Principle # 4: Simplicity

We perceive the simplest shapes possible

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Gestalt Principle # 5: Closure

Occurs when people see a familiar pattern or shape with some missing parts

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Perceptual Interference Perceptions are not always based on sensory information Perceptual interference: occurs when we fill in the gaps in

what our senses tell us

Figure 7.2 A reversible figure-ground design. Do you see two faces in profile or a wineglass?

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Figure 7.3 Perceptual grouping illustrations.

Figure 7.4 Human factors engineering. (a) Early roll indicators in airplanes were perceptually confusing and difficult to read (top). Improved displays are clear even to nonpilots. Which would you prefer if you were flying an airplane in heavy fog? (b) Even on a stove, the placement of controls is important. During simulated emergencies, people made no errors in reaching for the controls on the top stove. In contrast, they erred 38 percent of the time with the bottom arrangement (Chapanis & Lindenbaum, 1959). (c) Sometimes the shape of a control is used to indicate its function, so as to discourage errors. For example, the left control might be used to engage and disengage the gears of an industrial machine, whereas the right control might operate the landing flaps on an airplane. (d) This design depicts a street intersection viewed from above. Psychologists have found that painting white lines across the road makes drivers feel they are traveling faster. This effect is even stronger if the lines get progressively closer together. Placing lines near dangerous intersections or sections of highway has dramatically lowered accident rates.

Figure 7.7 (Above) An impossible figure—the “three-pronged widget.” If you cover either end of the drawing, it makes sense perceptually. However, a problem arises when you try to organize the entire drawing. Then, the conflicting information it contains prevents you from forming a stable perception. (Below) It might seem that including more information in a drawing would make perceptual conflicts impossible. However, Japanese artist Shigeo Fukuda has shown otherwise. (“Disappearing Column” © Shigeo Fukuda, 1985.)

Depth Perception

Definition: Ability to see three dimensional space and to accurately judge distances

Visual Cliff: Apparatus that looks like the edge of an elevated platform or cliff

Depth Cues: Features that supply information about distance and space

Monocular Depth Cue: Depth cue that can be sensed with one eye

Binocular Depth Cue: Depth cue that can be sensed with two eyes

Figure 7.9 Human infants and newborn animals refuse to go over the edge of the visual cliff.

Figure 7.14 (a) Linear perspective. (b) Relative size. (c) Light and shadow. (d) Overlap. (e) Texture gradients. Drawings in the top row show fairly “pure” examples of each of the pictorial depth cues. In the bottom row, the pictorial depth cues are used to assemble a more realistic scene.

Figure 7.16 (Above) We typically make two assumptions when using light and shadow to judge depth in a picture or drawing. First, we usually assume that light comes mainly from one direction. Second, we tend to assume that the source of light is above pictured objects. Squint a little to blur the image you see here. You should perceive a collection of globes projecting outward. If you turn this page upside down, the globes should become cavities. (After Ramachandran, 1995.) (Below) The famed Dutch artist M. C. Escher violated both assumptions about light to create the dramatic illusions of depth found in his 1955 lithograph “Convex and Concave.” In this print, light appears to come from all sides of the scene. (Courtesy of the Collection Haags Gemeente Museum, The Hague. © 1994 M. C. Escher/Cordon Art, Baarn, The Netherlands. All rights reserved.)

Illusion: Misleading or distorted perception Hallucination: When people perceive objects or events that

have no external basis in reality Moon Illusion: Apparent change in size that occurs as the

moon moves from the horizon (large moon) to overhead (small moon)

Ames Room: Distorted room that appears normal when viewed from a specific location

Muller-Lyer Illusion: Two equal length lines topped with inward or outward pointing V’s appear to be of different length; based on experience with edges and corners

Illusions: Is What You See What You Get?

Figure 7.6 Necker’s cube. Visualize the top cube as a wire box. If you stare at the cube, its organization will change. Sometimes it will seem to project upward, like the lower left cube; other times it will project downward. The difference lies in how the brain interprets the same information.

Visual Illusion

Please choose the button below that corresponds to the type of operating system you are using:

Figure 7.19 The Ponzo illusion may help you understand the moon illusion. Picture the two white bars as resting on the railroad tracks. In the drawing, the upper bar is the same length as the lower bar. However, because the upper bar appears to be farther away than the lower bar, we perceive it as longer. The same logic applies to the moon illusion.

Figure 7.23 The Ames room. From the front, the room looks normal; actually, the right-hand corner is very short, and the left-hand corner is very tall. In addition, the left side of the room slants away from viewers. The diagram shows the shape of the room and reveals why people appear to get bigger as they cross the room toward the nearer, shorter right corner.

Figure 7.26 Some interesting perceptual illusions.

Figure 7.27 Why does line (b) in the Müller-Lyer illusion look longer than line (a)? Probably because it looks more like a distant corner than a nearer one. Because the vertical lines form images of the same length, the more “distant” line must be perceived as larger. As you can see in the drawing on the right, additional depth cues accentuate the Müller-Lyer illusion. (After Enns & Coren, 1995.)

Selective Attention: When we give some messages priority over others

Divided Attention: Occurs when one divides attention among tasks

Habituation: When one responds less to a stimulus Orientation Response: Prepares us to receive information

from a stimulus

Motives and Perception

Figure 7.8 Stimuli similar to those used by Kennedy (1983) to study the kinds of information universally recognized in drawings. (See text for explanation.)

Figure 7.29 One of the drawings used by Mackworth and Loftus (1978) to investigate attention. Observers attend to unexpected objects longer than they do to expected objects. In this drawing, observers looked longer at the octopus than they did at a tractor placed in the same spot. What do you think would happen if a tractor were shown upside down or on the roof of the barn?

Definition: Past experiences, motives, contexts or suggestions that prepare us to perceive in a certain way

Bottom-Up Processing: Analyzing information starting at the bottom (small units) and going upward to form a complete perception

Top-Down Processing: Preexisting knowledge that is used to rapidly organize features into a meaningful whole

Perceptual Expectancies (Set)

Figure 7.24 Are the center dots in both figures the same size?

Parapsychology: Study of ESP and other psi phenomena (events that seem to defy accepted scientific laws). Four types of psi phenomena: Clairvoyance: Purported ability to perceive events at a

distance or through physical barriers Telepathy: Purported ability to read minds Precognition: Purported ability to accurately predict the

future Psychokinesis (Mind Over Matter): Purported ability to

influence physical objects by willpower

Extrasensory Perception (ESP): Fact or Fallacy?

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Extrasensory Perception (ESP) The ability to gain information by some means other than the

normal senses Paranormal phenomena and parapsychology

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The “Sixth Sense” The major focus includes the following: Telepathy,

clairvoyance, precognition, and psychokinesis

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Telepathy Communication of thoughts from one mind to another that

occurs without the use of our known senses

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Clairvoyance The ability to perceive objects and events without using the

senses

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Precognition and Psychokinesis Precognition: the ability to foretell the future Psychokinesis: the ability to move objects through mental

effort alone

More ESP Issues

Zener Cards: Deck of 25 cards, each having one of five symbols

Run of Luck: Statistically unusual outcome that could occur by chance alone; e.g. getting five heads in a row, two jackpots within 6 pulls of a slot machine

Stage ESP: Simulation of ESP for entertainment purposes Very popular on university campuses, since

undergraduates are fooled quite easily! Also popular in Las Vegas

Conclusion: Existence of ESP has NOT been scientifically demonstrated. Positive results are usually inconclusive and easily criticized

In sum: Be skeptical! If it seems too good to be true it probably is!