PSYA01H3 Chapter Notes - Chapter 4: Absolute Threshold, Neural Adaptation, Sound

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Published on 5 Aug 2018
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Sensation and perception Are Distinct Activities
Sensation
Simple stimulation of a sense organ
Basic registration of light, sound, pressure, odor, or taste as parts of your
body interact with the physical world
After sensation registers in your central nervous system, perception takes
place at the level of your brain
Perception
The organisation, identification, and interpretation of the sensation in
order to form a mental representation
Transduction
Occurs when many sensors in the body convert signals from the
environment into encoded nerve signals sent to the central nervous
system
Psychophysics
Methods that measure the strength of the stimulus and the Observer sensitivity to
that stimulus
Measuring thresholds
Absolute threshold
the minimum intensity needed to just barely detect a stimulus in 50% of
the trial
threshold is a boundary
Just noticeable difference
the minimum change in a stimulus that can just barely be detected
Weber's law
the just noticeable difference of a stimulus is a constant proportion
despite variations in intensity
Signal detection Theory
the response to a stimulus depends both on a person's sensitivity to the stimulus
in the presence of noise and on a person's decision criterion
Sensory adaptation
sensitivity to prolonged stimulation tends to decline over time as an organism
adapts to current conditions
Sensing light
Visual activity
the ability to see fine detail
Light waves have three properties: link, amplitude, and purity
What human see from these properties are color, brightness, and
saturation
Length - What we perceive as color
Amplitude- brightness
Purity - saturation or richness of color
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the human eye
Eyes have evolved as specialized organs to detect light
Light that reaches the eyes pass through a clear, smooth outer tissue called the
cornea
which bends the light wave and sends it through the pupil
Iris - Translucent, donut shaped muscle that controls the size of the pupil and
hence the amount of light that can enter the eye
Immediately behind the iris, is muscles inside the eye control the shape of
the lens to bend the light again and focus it onto the retina
Retina
light-sensitive tissue lining the back of the eyeball
Accommodation
the process by which the eye maintains a clear image on the retina
Nearsightedness - myopia
Farsightedness - hyperopia
from the eye to the brain
There are two types of photoreceptor cells in the retina that contain light-sensitive
pigment that translate light into neural impulses: cones and rods
Cones
detect color, operate under normal daylight conditions, and allow us to
focus on fine detail
Rods
become active under low light conditions for night vision
much more sensitive photoreceptors than cones
Fovea
The area of the retina where vision is the clearest in there are no robbed
it all
Pathways for what, where, and how
the ventral stream travels across the occipital lobe into the lower levels of the
temporal lobe and includes brain areas that represent an object's shape and
identity
essentially a “what” pathway
the dorsal stream travels up from the occipital lobe to the parietal lobes
connecting with brain areas that identify the location and motion of an object
Essentially a “where” pathway
Summary:
Light passes through several layers in the eyes to reach the retina. Two types of
photoreceptor cells in the retina translate light into neural impulses: cones, which
operate under normal daylight conditions and sense color; and rods, which are
active under low light conditions for night vision. the neural impulses are sent
along the optic nerve to the brain
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Document Summary

Basic registration of light, sound, pressure, odor, or taste as parts of your body interact with the physical world. After sensation registers in your central nervous system, perception takes place at the level of your brain. The organisation, identification, and interpretation of the sensation in order to form a mental representation. Occurs when many sensors in the body convert signals from the environment into encoded nerve signals sent to the central nervous system. Methods that measure the strength of the stimulus and the observer sensitivity to. The response to a stimulus depends both on a person"s sensitivity to the stimulus in the presence of noise and on a person"s decision criterion. Sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions. Light waves have three properties: link, amplitude, and purity the ability to see fine detail. What human see from these properties are color, brightness, and saturation. Length - what we perceive as color.

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