Chapter 1: Introduction to Perception

_______________

• The simple “elementary” processes that occur right at the beginning of the sensory system

• ex.) light reaching the eye, sound waves reaching the ear

Sensation

______________

• The complex processes that involve higher-order mechanisms that involve activity in the brain

• ex.) determining the movement of an object, identifying a song you like

Perception

The ___________ Process

• A 7-step process beginning with a stimulus in the environment to perceiving, recognizing, and acting on the stimulus

Perceptual

7 steps of the perceptual process:

1)

2)

3)

4)

5)

6)

7)

1) distal stimulus

2) proximal stimulus

3) receptor processes

4) neural processing

5) perception

6) recognition

7) action

The Perceptual Process

Step 1 and 2: The Stimulus

• Distal stimulus

→ a stimulus observed in the ___________

→ stimulus is “______”

• Proximal stimulus

→ The representation of the distal stimulus on the receptors

→ stimulus is in “__________” to the receptors

environment

distant

proximity

The Perceptual Process

Step 1 and 2: The Stimulus

→ Principle of _____________

• Stimuli and responses created by stimuli are transformed, or changed, between the distal stimulus and perception

• The representation of the proximal stimulus can change from how the distal stimulus exists in the environment:

1) properties of the energy source

2) properties of the stimulus

3) properties of the environment

transformation

The Perceptual Process

Step 1 and 2: The Stimulus

→ Principle of _____________

• Everything a person perceives is based on representations of stimuli that are formed on the receptors and the resulting activity in the person’s nervous system, not on direct contact with stimuli

representation

The Perceptual Process

Step 3: Receptor Processes

→ __________ _________

• cells specialized to respond to environmental energy

• each sensory system’s _______ specialized to respond to a specific type of energy

→ _______ - light

→ _________ - changes in air pressure

→ _____ - changes in pressure on skin

→ _____ - chemicals entering nose

→ ______ - chemicals entering mouth

sensory receptors

receptors

vision

hearing

touch

smell

taste

The Perceptual Process

Step 3: Receptor Processes

1) Transform ____________ energy into _________ energy

2) Shape perception by the way they respond to different properties of the stimuli

• Transduction

→ The transformation of ___________ energy into ___________ energy

→ ex.) light → photoreceptor → visual pigment → nerve impulse

environmental → electrical (x2)

The Perceptual Process

Step 4: Neural Processing

• __________ ___________

→ Operations that transmit electrical signals within a network of neurons

→ operations that transform the response of individual neurons

neural processing

The Perceptual Process

Step 5-7: Perception, Recognition, and Action

Which is which?

1) Conscious awareness or experience of a stimulus?

2) The ability to place an object in a category that gives it meaning?

3) Motor activities response to a stimulus?

1) perception

2) recognition

3) action

Any information that the perceiver brings to a situation

knowlege

processing based on incoming stimuli from the environment

data-based processing

bottom-up processing

processing based on the perceiver’s previous knowledge

knowledge-based processing

top-down processing

__________ (step 1-2)

→ distal

→ proximal

____________ (step 3-4)

→. receptors

→ processing

_____________ (steps 5-7)

→ perception

→ recognition

→ action

stimulus

physiology

behavior

Relationship A: Stimulus-Behavior

________________: the branch of psychology that deals with the relationships between physical stimuli and psychological responses

psychophysics

Relationship A: Stimulus-Behavior

_______ ________ ____

• the smallest width of lines a participant can detect

• stimuli - oriented gratings

• behavior - orientation detection

Grating acuity task

Relationship B: Stimulus-Physiology

_________ _______: enhanced sensitivity to vertically and horizontally oriented visual stimuli compared to obliquely (diagonal) oriented stimuli

oblique effect

Relationship B: Stimulus-Physiology

__________ ______________ _____

• recorded brain activity for each orientation

• stimuli - oriented gratings

• physiological response - brain activity (optical brain imaging)

grating sensitivity task

Relationship C: Physiology-Behavior

• Grating sensitivity task

→ physiological response - _____ ________ (______)

→ behavior - _________ ___________

brain activity (fMRI)

orientation detection

Measuring Perception

__________: the minimum stimulus energy necessary for an observer to detect a stimulus

threshold

___________ _________: the smallest stimulus level that can just be detected

absolute threshold

Which of the 5 senses go with each absolute threshold?

1) a candle seen from 30 miles away on a clear, dark night

2) a ticking watch that is 20 feet away in an otherwise quiet room

3) one drop of perfume diffused in a three-room apartment

4) one teaspoon of sugar dissolved in 2 gallons of water

5) the wing of a bumblebee falling on one’s cheek from a distance of 1 centimeter

1) vision

2) hearing

3) smell

4) taste

5) touch

Measuring Thresholds

________ ________ (1801-1887)

• proposed that the mind could be studied by measuring the relationship between changes in physical stimulation and a person’s experience

• developed the three classical phsyophysical methods for measuring the thresholds:

1) method of limits

2) method of constant stimuli

3) method of adjustment

Gustav Fechner

Fechner’s three classical psychophysical methods for measuring the threshold:

1)

2)

3)

1) method of limits

2) method of constant stimuli

3) method of adjustment

Method of?

The experimenter presents stimuli in either ascending (inc. intensity) or descending (dec. intensity) order for a sequence of stimuli

ex.) a person’s threshold for hearing a tone is measured using an ascending and descending method of limits

Method of limits

Method of?

The experimenter presents stimuli of differing intensity in random order

The threshold is defined as the intensity that results in detection ___% of trials

Requires a preliminary estimate of threshold to decide on presented stimulus values

ex.) a person’s threshold for lightbulb intensity is measured using the method of constant stimuli

method of constant stimuli

50%

Method of?

The participant—rather than the experimenter—adjusts the stimulus intensity continuously until they can just barely detect the stimulus

ex.) measuring macular pigment (alternating “flickering” blue/green test stimulus)(participant adjusts intensity of blue and green LED lights)

method of adjustment