Sensation and Perception Chapter 5 Psychology Notes PDF

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Summary

These notes contain all the material that needs to be learned for Chapter 5 in psychology which includes vocabulary....

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Sensation –

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The sense organs’ detection of external physical stimulus and the transmission of information about this stimulus to the brain

Perception –

The processing, organization, and interpretation of sensory signals in the brain; these processes result in an internal neural representation of the physical stimulus

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Sensory receptors: Sensory organs that detect physical stimulation from the external world and change that stimulation into information that can be processed by the brain

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Transduction: A process by which sensory receptors change physical stimuli into signals that are eventually sent to the brain

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Absolute threshold: The smallest amount of physical stimulation required to detect a sensory input half of the time it is present

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Difference threshold: The minimum difference in physical stimulation required to detect a difference between sensory inputs

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Weber’s law

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Just noticeable difference

Detection of a faint stimulus requires a judgment—it is not an all-or-none process •

Signal detection

theory helps us understand how a person can be biased toward either responding or not responding, despite being given the same amount of sensory input –

Sensory Adaption: A decrease in sensitivity to a constant level of stimulation

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Focusing light in the eye

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The light waves pass through the cornea of the eye

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The light then passes through the pupil

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The iris, a circular muscle, gives eyes their color and controls the pupil’s size to determine how much light enters the eye

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Lens: The adjustable, transparent structure behind the pupil; this structure focuses light on the retina, resulting in a crisp visual image

The thin inner surface of the back of the eyeball; this surface contains the sensory receptors –

Rods: Sensory receptors in the retina that detect light waves and transduce them into signals that are processed in the brain as vision. Rods respond best to low levels of illumination, and therefore do not support color vision or detection of fine detail

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Cones: Sensory receptors in the retina that detect light waves and transduce them into signals that are processed in the brain as vision. Cones respond best to higher levels of illumination, and therefore they are responsible for letting us see color and fine detail –

Each retina holds approximately 120 million rods and 6 million cones. Near the center of the retina is a small region called the fovea where cones are densely packed

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Information about what the eye has sensed is delivered to the ganglion cells

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The axons of each ganglion cell are gathered into a bundle. This bundle is called the optic nerve

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There are blind spots in your left and right visual fields, where the optic nerve exits the retina

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Half of the axons in the optic nerves cross to the other side of the brain. The rest of the axons stay on the same side of the brain. –

The point where the axons cross is known as the optic chiasm

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The information passes through the thalamus and travels to the primary visual cortex in the occipital lobes

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For humans, visible light consists of electromagnetic waves ranging in length from about 400 to 700 nanometers

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The amplitude is the height of the light wave from base to peak; people experience this quality as brightness

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The wavelength of the light wave is the distance from peak to peak. This distance determines your perception of both hue and saturation

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Hue refers to the distinctive characteristics that place a particular color in the spectrum

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Saturation is the intensity of the color

The combining of wavelengths is called additive color mixing

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The combining of pigments is called subtractive color mixing

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The proposal that ganglion cells in the retina receive excitatory input from one type of cone and inhibitory input from another type of cone, creating the perception that some colors are opposites

The founders of Gestalt psychology postulated a series of laws to explain how our brains group the perceived features of a visual scene into organized wholes – –

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The perception of objects is due to the complex analysis of prior experiences and expectations within the brain; this analysis influences how sensory receptors process stimulus input from the environment

Binocular depth cues –

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The perception of objects is due to analysis of environmental stimulus input by sensory receptors; this analysis then influences the more complex, conceptual processing of that information in the brain

Top-down processing –

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The visual system’s organization of features and regions to create the perception of a whole, unified object

Bottom-up processing –

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Figure ground: An object is a figure that is distinct from the background. The background is referred to as the ground

Cues of depth perception that arise because people have two eyes

Monocular depth cues –

Cues of depth perception that are available to each eye alone Binocular Disparity: We use both eyes to perceive depth through binocular disparity, where each retina has a slightly different view of the world

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Pictorial depth cues •

Occlusion

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Height in field

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Relative size

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Familiar size

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Linear perspective

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May occur when you gaze at a moving image for a long time and then look at a stationary scene •

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Motion aftereffects are strong evidence that motion-sensitive neurons exist in the brain

Movies are made up of still images, each of which is slightly different from the one before it. When the series is presented fast enough, we perceive the illusion of motion pictures •

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Texture gradient

This perceptual illusion is called stroboscopic motion

This sensory mechanism enables us to determine what is happening in our environments •

It provides a medium for spoken language

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It brings pleasure to our lives (for example, through music)

From the ear to the brain –

The process of hearing begins when sound waves arrive at the shell-shaped structure of your outer ear •

The shell shape of the outer ear increases the ear’s ability to capture sound waves and then funnel the waves down the auditory canal

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Eardrum: A thin membrane that marks the beginning of the middle ear; sound waves cause the eardrum to vibrate

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Cochlea: A coiled, bony, fluid-filled tube in the inner ear that houses the sensory receptors •

Running through the center of the cochlea is the thin basilar membrane

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Hair cells: Sensory receptors located in the cochlea that detect sound waves and transduce them into signals that ultimately are processed in the brain as sound

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Transduction initiates the creation of action potentials in the auditory nerve. The auditory nerve sends the information to the sensory processing center of the thalamus and finally to the primary auditory cortex in the brain

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The height of the sound waves is called the amplitude. •

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Amplitude determines our perception of loudness

The distance between peaks of sound waves is the wavelength •

The time between the peaks in wavelength is called the frequency

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The frequency of the waves determines the pitch of the sound, from high to low

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Place coding: The perception of higher-pitched sounds depends on the point on the basilar membrane where hair cells are stimulated by sound waves of varying higher frequencies

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The ear estimates the location of a sound based first on when the sound arrives and second on the amplitude, or intensity, of the sound wave

Together, taste and smell produce the experience of flavor. In fact, flavor is based more on smell than on taste –

The sense of taste is also called gustation

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The sense of smell is also called olfaction

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Taste buds: Structures, located in papillae on the tongue, that contain the sensory receptors

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Papillae: Structures on the tongue that contain groupings of taste buds •

The taste information is sent to other brain regions through a set of nerves, primarily the facial nerve

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After processing by the thalamus, the information is further processed in the gustatory cortex

Five main tastes –

Sweet, sour, salty, bitter, and umami (Japanese for “savory” or “yummy”) •

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Supertasters have nearly six times as many taste buds as normal tasters

Taste preference –

Texture of food affects taste preferences

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Whether the food causes discomfort affects preference •

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Umami was discovered in 2007 and is the most recently recognized taste sensation

Supertasters are highly aware of flavors and textures and are more likely than others to feel pain when eating very spicy foods •

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Temporal coding: The perception of lower-pitched sounds is a result of the rate at which hair cells are stimulated by sound waves of lower frequencies

Spicy chilies

Cultural influences on food preferences begin in the womb

When a dog is out for a walk, why does it sniff virtually every object and creature it encounters? –

The sense of smell, which is also called olfaction, is the dog’s main way of perceiving the world

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Olfactory epithelium: A thin layer of tissue, deep within the nasal cavity, that contains the olfactory receptors; these sensory receptors produce information that is processed in the brain as smell •

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Olfactory bulb: A brain structure above the olfactory epithelium in the nasal cavity; from this structure, the olfactory nerve carries information about smell to parts of the brain, including the olfactory cortex •

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Unlike all other forms of other sensory information, smell signals bypass the thalamus

Variety of smells –

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Chemical molecules are called odorants

There are thousands of olfactory receptors in the olfactory epithelium •

Each receptor responds to different odorants

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According to a recent estimate, humans can distinguish more than a trillion odorants

Smell perception –

Information about whether a smell is pleasant or unpleasant is processed in the brain’s prefrontal cortex

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The smell’s intensity is processed in the amygdala, a brain area involved in emotion and memory •

Most people are pretty bad at identifying odors by name

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When you see, hear, taste, or smell something, receptors in just one small part of your body have been stimulated

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Touch receptors exist all over your body –

The skin is the largest organ for sensory reception

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Warm receptors: Sensory receptors in the skin that detect the temperature of stimuli and transduce it into information processed in the brain as warmth

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Cold receptors: Sensory receptors in the skin that detect the temperature of stimuli and transduce it into information processed in the brain as cold

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Sensory receptors in the skin that detect tactile stimulation and transduce it into information processed in the brain as different types of pressure on the skin

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Touch information travels first through the thalamus and then to the somatosensory cortex, which processes the information

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Penfield discovered that electrical stimulation of the primary somatosensory cortex could evoke the perception of touch in different regions of the body

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For the most sensitive regions of the body, such as the lips and fingers, a great deal of the cortex is dedicated to processing touch

Two types of pain receptors –

Fast fibers: Myelinated fibers quickly convey intense sensory input to the brain, where it is perceived as sharp, immediate pain.

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Slow fibers: Unmyelinated fibers slowly convey intense sensory input to the brain, where it is perceived as chronic, dull, steady pain

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We experience pain when pain receptors are activated and a neural “gate” in the spinal cord allows the signals through to the brain

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This theory is radical in that it views pain as a perceptual experience within the brain rather than simply a response to nerve stimulation

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Distraction can reduce your perception of pain •

Listening to music is an extremely effective way to reduce postoperative pain, perhaps because it helps patients relax

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Our kinesthetic sense tells us how our body and limbs are positioned in space

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Our vestibular sense allows us to maintain balance...