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Psychology 1000 Study Guide - Midterm Guide: Jet Lag, Endorphins, Preconscious

Course Code
PSYCH 1000
John Campbell
Study Guide

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Psychology Midterm 2 Review
Chapters 5-8
Chapter 5: Sensation and Perception
Synesthesia, which means quite literally “mixing of the senses”.
Synesthetes may experience sounds as colours or tastes as touch sensations that have different shapes.
Women are more likely to be synesthetes than men.
Sensation Process: Sensation 1) Stimulus is received by sensory neurons 2) Receptors translate
stimulus properties into nerve impulses (transduction) 3) Feature detectors analyze stimulus features
4) Stimulus features are reconstructed into neural representation 5) Neural representation is compared
with previously stored information in brain 6) Matching process results in recognition and
interpretation of stimuli. Perception
The binding problem: How do we bind all our perceptions into one complete whole while keeping its
sensory elements separate?
People with synesthesia may create additional perceptions of that rose that are inconsistent with its
physical properties.
Sensation is the stimulus-detection process by which our sense organs respond to and translate
environmental stimuli into nerve impulses that are sent to the brain.
Perception - making “sense” of what our senses tell us- is the active process of organizing this
stimulus input an giving it meaning.
Transduction is the process whereby the characteristics of a stimulus are converted into nerve
Decision Criterion, a standard of how certain they must be that a stimulus is present before they will
say they detect it.
Sensation refers to the activities by which our sense organs receive and transmit information, whereas
perception involves the brain's processing and interpretation of the information.
Psychophysics is the scientific study of how the physical properties of stimuli are related to sensory
experiences. Sensory sensitivity is concerned in part with the limits of stimulus detectability (asolute
threshold) and the ability to discriminate between stimuli (difference threshold).
The absolute threshold is the intensity at which a stimulus is detected 50 percent of the time.
Signal Detection Theory is concerned with factors that influence decisions about whether or not a
stimulus is present.
Subliminal Stimuli, which are not consciously perceived, can influence perceptions and behaviour in
subtle ways, but bot strongly enough to justify concerns about the subconscious control of behaviour
through subliminal messages.
The Difference Threshold, or just noticeable difference, is the amount by which two stimuli must
differ for them to be perceived as different 50 percent of the time.
Weber's law: the jnd is proportional to the intensity of the genreal stimulus and is constant within a
given sense modality.
Sensory Systems are particularly responsive to changes in stimulation, and adaptation occurs in
response to unchanging stimuli.
Our vision, measured in nanometers, extends from 700 to 400 nanometers.
Light waves enter through the cornea. Behind the cornea is the pupil, an adjustable opening that can
dilate or constrict to control the amount of light. Pupil's movements are controlled by the iris. Behind
the pupil is the lens (thinner on far objects, thicker on near objects). The retina is a multi-layered tissue

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at the rear of the eyeball.
Myopia: nearsightedness.
Hyperopia: farsightedness.
The retina contains specialized sensory neurons and is an extension of the brain.
The retina contains two types of light-sensitive receptor cells called rods and cones.
There are 120 million rods and 6 million cones in the human eye.
Rods are primarily black and white brightness receptors, and are about 500 times more sensitive to
light than cones, however they do not give rise to colour sensations.
Cones, which are colour receptors, function best in bright illumination.
Rods and cones are fond throughout the eye except in the fovea, which contains only cones.
Bipolar cells have synaptic connections with the rods and cones. These cells then synapse with a layer
of about one million ganglion cells whose axons are collected in into a bundle to form the optic nerve.
Visual acuity, or ability to see fine detail, is greatest when the visual image projects directly onto the
Rods and cones translate light waves into nerve impulses through the action of protein molecules called
Dark Adaptation is the progressive improvement in brightness sensitivity that occurs over time under
conditions of low illumination. (during which the photopigment molecules are regenerated and the
receptor's sensitivity increases greatly.
Trichromatic Theory: there are three types of colour receptors in the retina.
Opponent-Process Theory: proposed that each of the three cone types responds to two different
wavelengths. (the canadian flag image)
Dual Process theory combines the trichromatic and opponent-process theories to account for the
colour transduction process.
Trichromats: people with normal vision. Dichromats: have a deficiency in one of the systems.
Monochromats: see only black and white (entirely colour blind).
From the retina, the optic nerve sends nerve impulses to a visual relay station in the thalamus, the
brain's sensory switchboard. From there, the input is routed to various parts of the cortex, particularly
the primary visual cortex in the occipital lobe at the rear of the brain. Some of these cells are called
feature detectors, which subdivide a visual scene into its component dimensions and process them
simultaneously (parallel processing).
The information, analyzed and recombined by the primary visual cortex, is routed to other cortical
regions known as the visual association cortex.
Sound is actually pressure waves in air, water, or some other conducting medium.
Sound waves, the stimuli for audition, have two characteristics: frequency, measured in terms of cycles
per second or hertz (humans can detect 20 to 20,000 hertz), and amplitude (the vertical size of the
sound waves) , measured in terms of decibels (db,a measure pf the physical pressures that occur at the
Frequency is related to pitch, amplitude is related to loudness.
Vibrating of these bones – the hammer (malleus), anvil (incus), and stirrup (stapes) – amplifies the
sound wavs more than 30 times.
The receptors for hearing are hair cells (16,000 of them) in the organ of Corti at the inner ear
Loudness is coded in terms of the number and types of auditory nerve fibres that fire. Pitch is coded in
two ways: 1) The Frequency Theory: Low frequency tones are coded in terms of corresponding
numbers of nerve impulses in individual receptors or by volleys of impulses from a number of
receptors. 2) The Place Theory: Frequencies above 4000 hertz are coded according to the region of the
basilar membrane that is displaced most by the fluid wave in the cochlear canal.

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Two ears play a crucial role in sound localization.
In Canada alone, almost 3 million people suffer from some form of hearing loss.
Conduction Deafness: caused by problems involving the mechanical system that transmits sound
waves into the cochlea. (i.e. A punctured eardrum)
Nerve Deafness: caused by damaged receptors within the inner ear or damage to the auditory nerve
itself, and it cannot be helped by a hearing aid. ( i.e. Exposure to loud sounds).
Gustation (taste) and olfaction (smell) are chemical senses because their receptors are sensitive to
chemical molecules rather than to some form of energy. These senses are so intertwined that some
scientists refer to a common chemical sense.
Gustation: our sense of taste responds to only 4 qualities: sweet, sour, salty, and bitter.
Taste Buds are chemical receptors concentrated along the edges and back surface of the tongue.
Humans have 9,000 taste buds. Each taste bud is responsive to only 2 of the 4 qualities.
The receptors for smell are long cells that project through the lining of the upper part of the nasal cavity
and into the mucous membrane.
Humans have 40 million olfactory receptors.
The receptors that fire send their input to the olfactory bulb, a forebrain structure immediately above
the nasal cavity.
Pheromones: chemical signals found in natural body scents.
Humans are sensitive to at least 4 tactile sensations: pressure (touch), pain, warmth, and cold.
Our skin weighs between 2.7 and 4.5 kilograms, and is the largest organ in the body.
Primary receptors for pain and temperature are free nerve endings, simple nerve cells beneath the skin's
surface that resemble the bare branches of a tree in winter.
Free nerve endings in the skin and internal organs respond to intense mechanical, thermal, or chemical
stimulation and then send nerve impulses into the spinal cord, where sensory tracts carry pain
information to the brain. Once in the brain, the sensory information is relayed by the thalamus to the
somatosensory and frontal areas of the cerebral cortex.
Gate Control Theory: proposes that the experience of pain results from the opening and closing of
gating mechanisms in the nervous system.
Glial cells are involved in the creation and maintenance of pathological pain.
The nervous system has built in analgesics (painkillers) with opiatelike properties. They are called
endorphins” which inhibit the release of neurotransmitters involved in the synaptic transmission of
pain impulses from the spinal cord to the brain.
Kinesthesis: provides us with feedback about our muscles' and joints' positions and movements. The
receptors are nerve endings in the muscles, tendons, and joints.
Vestibular Sense: the sense of body orientation or equilibrium, located in the vestibular apparatus.
Sensory Prosthetic Devices: provide sensory input that can substitute for what cannot be supplied by a
person's sensory receptors.
Perception involves both bottom-up processing, in which individual stimulus fragments are combined
into a perception, and top-down processing, in which existing knowledge and perceptual schemas are
applied to interpret stimuli.
Inattentional Blindness refers to the failure of unattended stimuli to register in consciousness.
Attention is an active process in which we focus on certain stimuli while blocking out other stimuli.
We cannot attend completely to more than one thing at a time, but we are capable of rapid attentional
Attentional processes are affected by the nature of the stimulus and by personal factors such as motives
and interests.
The perceptual system is especially vigilant to stimuli that denote threat or danger.
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