04/19/23

SENSATION AND PERCEPTION

MCGONIGLE

INTRO TO PSYCHOLOGY

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Example of Determining Factor:

• Sentry : at wartime

• Sentry: at peacetime

• Who will be more likely to sense danger?

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Sensory Adaptation

• Imagine yourself at a bonfire, marshmallow roast, what happens to the faces in the background after a while?

• What animals see better in the night time as opposed to day? Why do you think this is true?

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Absolute Threshold

• Weakest amount of a stimulus that can be sensed.

• Dogs – can hear certain whistles that we can not hear.

• Biological & Psychological factors determine different thresholds.

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Difference Threshold

• The minimum amount of difference that can be detected between two stimuli is known as the difference threshold.

• Dark blue/ Navy blue – could you tell the difference? Stang baseball hats- maroon?

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Signal Detection Theory

• Method of distinguishing sensory stimuli that takes into account not only their strengths, but :

• Setting• Physical state• Mood• Attitudes

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Eye

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Sensory Adaptation

• We become more sensitive to weak stimuli such as the faces around the fire.

• We become less aware of the heat of the fire or the sound of the wood burning or the smell of the marshmallows.

• “Attleboro apartment near commuter rail”

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Threshold Receptors

• Vision: Rods and cones in the retina.

• Hearing : Hair cells of the inner ear.

• Smell : Receptor cells in the nose.

• Taste: Taste buds on the tongue.

• Touch: Nerve endings on the skin.

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Light

• Think of a rainbow/ prism

• What colors are most brilliant to you?

• Main colors of spectrum: (Roy G Biv)

• Red, Orange, Yellow, Green, Blue, Indigo, Violet.

• Not visible* - Infrared and ultraviolet.

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Eye

• Amount of light that enters the eye is determined by the size in the opening in the colored part of the eye. (pupil)

• Pupil dilation : discussion• Lens : adjusts to the distance of objects by

changing its thickness.

• FST – why do people squint? Eye glasses/ contac lens..

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Human Eye (cont’d)

• Retina: sensitive surface in the eye that acts like film in a camera. Made up of neurons not film.

• Photoreceptors: once the light hits the photoreceptors, a nerve carries the visual input to the brain.

• Blind spot: Where optic nerve leaves the eye 4-3.

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Eye ( last slide)

• Rods and Cones: Rods are sensitive only to the brightness of light.

• Rods : allow us to see in black and white

• Cones: allow us to see in color.

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Visual Acuity

• Sharpness of vision is called visual acuity.

• Snellen Vision Chart : 20/20

• Nearsighted, Farsighted. (Myopia, Hyperopia)

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Snellen Chart

• T E

• P V L

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Snellen Chart

H C O E

H P D N L Z A

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Snellen Chart

D V H T L U

E V O C U C

P C Y L H N

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Snellen Last

» P C Y L h D v

»Don’t squint!!!!!!

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Color Circle

• Each color has a complementary partner

• Discussion of Traffic Lights

• Why are school buses yellow??

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Afterimage/ Color Blindness

• Afterimage : Of a color is its complementary color. ( USA Flag)

• Color blind: unable to distinguish color due to an absence of or malfunction in the cones.

• Total Color blindness : is very rare..

• Socks – Black socks / Navy blue – hard for men.

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Hearing

• Pitch: How high or low a sound is depends on its frequency or # of cycles per second.

• AI – term used often..

• More cycles per second, the higher the pitch.

• Women’s voices: higher pitch than men, shorter vocal cords.

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Loudness

• Loudness: determined by the height, or amplitude , of sound waves.

• Higher the amplitude: the louder the sound.

• Loudness is measured in decibels. ( 0 = watch ticking 20” away in a quiet room)

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Ear

• Shaped to capture sound waves, the outer ear is what we see.

• Eardrum: thin membrane that vibrates when sound hits it.

• Transmits sound to the three bones in the ear. ( hammer, anvil, and stirrup)

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Cochlea

• Latin for Snail ( Its shape) in the inner ear.

• Contains fluids & neurons that move in response to vibrations of the fluids.

• Movement - Generates neural impulses that are transmitted to the brain.

• Auditory nerve – transmits this message.

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Deafness

• Conductive Deafness: Occurs because of damage to the middle ear.

• Sensorineural deafness: Caused by damage to the inner ear. Neurons in cochlea are destroyed or damage to auditory nerve.

• What occupations would experience sensorineural deafness?

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Other Senses: Smell & Taste

• Dogs : incredible sense of smell..

• Helen Keller ( 90)

• Onion/ Apple w/out smell???

• Odors: are detected by neurons in each nostril.

• Receptors: send info to the brain via the olfactory nerve.

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Taste

• 5 Taste Buds

• Sweetness, Sourness, Saltiness, Bitterness, Umami

• Without a sense of smell, our sense of taste can be compromised..

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Skin Senses

• Some are more sensitive than others:

• P.91

• Fingertips

• Lips

• Cheeks

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Less sensitive to touch

• Shoulders

• Thighs

• Calves

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Temperature

• 98.6

• Neurons – beneath the skin

• Hot day- receptors for warmth fire

• Cold day- receptors for cold fire

• Adjustment – cold water after a while

• NE Patriot fan vs. Miami Dolphin fan !!!

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Pain

• Not all areas are equally sensitive to pain.

• Pain – point of contact 1st.• Pain - sent to the spinal cord 2nd.• Pain – now enters the thalamus in the

brain.• Pain – ends in the cerebral cortex.

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Gate Theory

• Gate = Limit

• Only a certain amount of info can be processed at one time.

• Rubbing the area can transmit sensations to the brain that compete w/ pain.

• Western Movies – “ Bite the bullet”

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Body Senses

• Vestibular sense: Tells you whether you are physically upright w/out using your eyes. ( gymnasts) - role of ears!

• Kinesthesis : sense that informs people about the position and motion of their bodies. (kinesiology)

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Perception

• Closure : Figure 4-10- Tendency to perceive a complete or whole figure even when there are gaps in what your senses tell you.

• Figure-Ground Perception: Vase vs. 2 faces. Is the perception of figures against a background

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Perception ( Cont’d)

• Proximity ( 6 lines)

• Similarity ( x’s + o’s)

• Continuity ( wavy lines)

• Common fate ( people running together)

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Stroboscopic Motion

• Page 95- give illusion of motion (cat)

• Illusion of motion – produced by showing the rapid progression of images or objects that are not moving at all.

• Little picture books- flipped to look like motion pictures.

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Visual Illusions

• Muller- Lyer illusions- which line is longer?

• Ponzo illusion – lines appear to be coming together.

• Rule of size constancy. ( looking at people from a plane)

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Quiz Thursday

Taste BudsRoy G BivRods & ConesLens & RetinaAbsolute ThresholdDifference ThresholdTypes of DeafnessBones in the EarDecibel levels