Chapter 5-Sensation and perception Flashcards
What is sensation and how does it enter the central
nervous system?
the activation of receptors in the various sense organs
enters through sensory receptors
What are sensory thresholds, and who were some of
the early pioneers in the study of sensory
thresholds?
Sensory threshold – weakest stimulus that an organism can detect
Ernst Heinrich Weber
Gustav Fechner
What is the difference between absolute thresholds
and just noticeable difference (jnd)
Absolute threshold - the smallest amount of energy needed for a person to consciously detect a stimulus 50 percent of the time it is present
Just noticeable difference jnd - the smallest difference between two
stimuli that is detectable 50 percent of the time
What is perception, and what is the difference
between bottom-up and top-down processing of
perception?
the way sensory information is organized, interpreted, and consciously
experienced
◦ Bottom-up processing – perceptions are built from sensory input
◦ Top-down processing – perceptions are influenced by our available knowledge, experiences, and thoughts
What are some of the factors that influence our
ability to perceive, and how do they relate to such
concepts as sensory adaptation, inattentional
blindness, signal detection theory, and the Muller-
Lyer illusion?
unchanging stimuli
◦ Sensory adaptation - tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging
Lack of attention
◦ Inattentional blindness - failure to notice something that is completely visible because of a lack of attention
Motivation
◦ Signal detection theory – the ability to identify a stimulus
when it is imbedded in a distracting background
Muller-Lyer Illusion- illusion of line length that is distorted by inward-turning or outward-turning corners on the ends of the lines, causing lines of equal length to appear to be different
How are “waves” related to vision and sound, and
what is meant by amplitude, wavelength, and
frequency?
Visual and auditory stimuli both occur in the form of waves
Amplitude - the height of a wave as measured from the highest point on the wave to the lowest point on the wave
◦ Wavelength – the length of a wave from one peak to the next
Frequency - the number of waves that pass a given point in a given time period and is often expressed in terms of hertz (Htz), or cycles per second
What is light, and what are the three aspects related
to light?
The influence of light waves on vision
1)Brightness
2)Color
3)Saturation
What is sound, and what are the three aspects
related to sound?
The influence of sound waves on hearing
1)Pitch
2)Volume
3)Timbre
What are the structures of the eye, and how do they
work together to produce vision?
Cornea – clear membrane that covers the surface of the eye; protects the eye and is the structure that focuses most of the light coming into the eye
Pupil – hole through which light from the visual image enters the interior of the eye
Iris - round muscle (the colored part of the eye) in which the pupil is located; can change the size of the pupil, letting more or less light into
the eye; helps focus the image
Lens – another clear structure behind the iris, suspended by muscles; finishes the focusing process begun by the cornea
Retina – final stop for light in the eye
What is colorblindness, and how is it caused?
Colorblindness - caused by defective cones in the retina
people that are colorblind cant see color properly they often mix red and green
What are the two theories proposed for how our eyes
see color, and how do they differ?
Trichromatic theory – three types of cones: red, blue, and
green (primary colors of light); the combination of cones and the rate at which they fire determine the color
Opponent-process theory - theory of color
vision that proposes four primary colors with
cones arranged in pairs: red and green, blue
and yellow
What is depth perception, and what did the visual
cliff experiment conclude?
The ability to perceive the world in three dimensions
The experiment demonstrated that most human infants can discriminate depth as soon as they can crawl.
Through what two processes of adaptation do the
eyes recover after being exposed to extreme
brightness or extreme darkness, and how are these
processes explained?
Dark adaptation - the recovery of the eye’s sensitivity to visual stimuli in darkness after exposure to bright lights
Light adaptation - the recovery of the eye’s sensitivity to visual stimuli in light after exposure to darkness
What is the difference between nearsightedness and
farsightedness?
Nearsightedness (myopia)- able to see objects clearly up close, but unable to focus on items further away
Farsightedness (hyperopia)- items far away are clear, but activities like reading and knitting are difficult, because nearby objects appear fuzzy or unfocused
What are the parts that make up the structure of the
ear, and how do they work together to produce
hearing?
Pinna – visible part of the ear that protrudes from our heads
Auditory canal - short tunnel that runs from the pinna to the eardrum
Tympanic membrane/Eardrum - thin section of skin that tightly covers the opening into the middle part of the ear, just like a drum skin covers the opening in a drum
Cochlea - snail-shaped structure of the inner ear that is filled with fluid
Basilar membrane – a thin strip of tissue within the cochlea
Organ of Corti – rests in the basilar membrane; contains receptor cells for sense of hearing
Hair cells- the sensory receptors of the auditory system
