Psych Chapter 3 Summary

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The ABC's of Sensation

3.1 Describe how we get information from the outside world into our brains

Sensation is the activation of receptors located in the eyes, ears, skin, nasal cavities, and tongue.

Sensory receptors are specialized forms of neurons that are activated by different stimuli such as light and sound.

3.2 Describe the difference and absolute thresholds.

A just noticeable difference is the point at which a stimulus is detectable half the time it is present.

Weber's law of just noticeable differences states that the just noticeable difference between two stimuli is always a constant.

Absolute thresholds are the smallest amount of energy needed for conscious detection of a stimulus at least half of the time it is present.

3.3 Explain why some sensory information is ignored

Subliminal stimuli are stimuli presented just below the level of conscious awareness, and subliminal perception has been demonstrated in the laboratory. It has not been shown to be effective in advertising.

Habituation occurs when the brain ignores a constant stimulus

Sensory adaptation occurs when the sensory receptors stop responding to a constant stimulus

The Science of Seeing

3.4 Describe how light travels through the various parts of the eye

Brightness corresponds to the amplitude of light waves, whereas color corresponds to the length of the light waves.

Saturation is the psychological interpretation of wavelengths that are all the same (highly saturated) varying (less saturated).

Light enters the eye and is focused through the cornea, passes through the aqueous humor, and then through the hole in the iris muscle called the pupil

The lens also focuses the light on the retina, where it passes through the ganglion and bipolar cells to stimulate the rods and the cones.

3.5 Explain how light information reaches the visual cortex

Visual pathway = retina -> optic nerve -> optic chiasm -> optic tract -> LGN of thalamus -> optic radiations -> primary visual cortex

Light from the right visual field projects to the left side of each retina; light from the left visual field projects to the right side of the eye

Axons from the temporal halves of each retina project to the visual cortex on the same side of the brain; axons from nasal halves of each retina project to visual cortex on the opposite side of the brain; optic chiasm is the point of crossover

3.6 Compare and contrast two major theories of color vision, and explain how color-deficient vision occurs

Rods detect changes in brightness but do not see color and function best in low levels of light. They are found everywhere in the retina except for the center, or fovea.

Cones are sensitive to color and work best in bright light. They are responsible for the sharpness of visual info and are found in the fovea.

The trichromatic theory of color perception assumes 3 primary colors: red, green, and blue. All colors would be perceived as various combos of these 3

The opponent-process theory of color perception assumes 4 primary colors: red, green, blue and yellow. Colors are arranged in pairs and when one member of a pair is activated the other is not.

Color blindness is a total lack of color perception, whereas color-deficient vision refers to color perception that is limited primarily to yellows and blues or reds and greens only.

The Hearing Sense: Can You Hear Me Now?

3.7 Explain the nature of sound and describe how it travels through the various parts of the ear.

Sounds has three aspects: pitch (frequency), loudness, and timbre (purity)

Sound enters the ear through the visible outer structure, or pinna, and travels to the eardrum and then to the small bones of the middle ear.

The bone called the stirrup rests on the oval window, causing the cochlea and basilar membrane to vibrate with sound.

The organ of Corti basilar membrane contains the auditory receptors, which send signals o the brain about sound qualities as they vibrate.

3.8 Summarize 3 theories of how the brain processes info about pitch

Place theory states that the locations of the hair cells on the organ of Corti correspond to different pitches of sound. This can explain pitch above 1,000 Hz

Frequency theory states that the speed with which the basilar membrane vibrates corresponds to the different pitches of sound. This can explain pitch below 1,000 Hz

The volley principle states that neurons take turns firing for sounds above 400 Hz and below 4,000 Hz

3.9 Identify types of hearing impairment and treatment options for each

Conduction hearing impairment is caused by damage to the outer or middle ear structures, whereas the nerve hearing impairment is caused by damage to the inner ear or auditory pathways in the brain.

Hearing aids may be used for those with conductive hearing impairment, while cochlear implants may restore some hearing to those with nerve hearing impairment.

Chemical Sense: It Tastes Good and Smells Even Better

3.10 Explain how the sense of taste works

Gustation is the sense of taste.

Taste buds in the tongue receive molecules of substances, which fit into receptor sites.

Gustation is a chemical sense that involves the detection of chemicals dissolved in saliva

The 5 basic tastes are sweet, sour, salty, bitter, and umami (brothy)

3.11 Explain how the sense of smells works

Olfaction is the sense of smell.

The olfactory receptors in the upper part of the nasal passages receive molecules of the substance and create neural signals that then go the olfactory bulbs under the frontal lobes.

Olfaction is a chemical sense that involves the detection of chemicals suspended in the air.

The Other Senses: What the Body Knows

3.12 Describe how we experience the sensations of touch, pressure, temperature, and pain

The skin senses are one part of our somesthetic senses

Pacinian corpuscles respond to pain and pressure, and free nerve endings respond to pain, pressure, and temperature.

The gate-control theory of pain states that when receptors sensitive to pain are stimulated, a neurotransmitter called substance P is released into the spinal cord, activating other pain receptors by opening "gates" in the spinal column and sending the message to the brain.

3.13 Describe the system that tells us about balance and position and movement of our bodies

The kinesthetic sense allows the brain to know about the movement of the body.

Proprioception, or information about where the body and its parts are in relation to each other and the ground, comes from the activity of special receptors responsive to movement of the joints and limbs.

The vestibular sense also contributes to the body's sense of spatial orientation and movement through the activity of the otolith organs (up-and-down movement) and the semicircular canals (movement through arcs).

Motion sickness is explained by sensory conflict theory, in which information from the eyes conflicts with information from the vestibular sense, causing nausea

The ABC's of Perception

3.14 Describe how perceptual constancies and the Gestalt principles account for common perceptual experiences.

Perception is the interpretation and organization of sensations.

Size constancy is the tendency to perceive objects always being the same size, no matter how close or far away they are.

Shape constancy is the tendency to perceive objects as the same shape even when the shape of the object changes on the retina of the eye.

Brightness constancy is the tendency to perceive objects as a certain level of brightness, even when the light changes.

The Gestalt psychologists developed several principles of perception that involve interpreting patterns in visual stimuli. The principles are figure-ground relationships, closure, similarity, continuity, contiguity, and common region.

3.15 Explain how we perceive depth using both monocular and binocular cues.

Depth perception is the ability to see in three dimensions.

Monocular cues for depth perception include linear perspective, relative size, overlap, aerial (atmospheric), texture gradient, motion parallax, and accommodation

Binocular cues for depth perception include convergence and binocular overlap.

3.16 Identify some common visual illusions and the factors that influence our perception of them.

Illusions are perceptions that do not correspond to reality or are distortions of visual stimuli

Perceptual set or expectancy refers to the tendency to perceive objects and situations in a particular way because of prior experiences.

Top-down processing involves the use of existing knowledge to organize individual features into a unified whole.

Bottom-up processing involves the analysis of smaller features, building up to a complete perception.

Applying Psychology to Everyday Life: Beyond "Smoke and Mirrors" - The Psychological Science and Neuroscience of Magic

3.17 Describe how the neuroscientific study of magic can help explain visual and cognitive illusions

Magicians take advantage of some well-known properties of our visual system to accomplish a variety of magic tricks

By collaborating with magicians, psychologists, and neuroscientists can learn more about magic and the brain processes responsible for our perception of magic tricks.