Sensation and Perception
The ABC’s Of Sensations
What Is Sensation?
Sensation is the activation of receptors located in the eyes, ears, skin, nasal
cavities, and tongue.
Sensory receptors are specialised forms of neurons and are activated by
different stimuli such as light or sound.
Sensory Thresholds
A just noticeable difference is the smallest differences between two stimuli that
are detectable 50% of the time.
Weber’s law of just noticeable difference states that the just noticeable difference
between two stimuli is always constant.
Absolute thresholds are the smallest amount of energy needed for conscious
detection of a stimulus at least half the time it is present.
Subliminal stimuli are just below the level of conscious awareness, but have not
been shown to affect behaviour in day-to-day life.
Habituation and Sensory Adaptation
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
Perceptual Properties of Light: Catching the Waves
Brightness corresponds to amplitude of light waves, while colour corresponds to
length of the light waves.
, Saturation is the psychological interpretation of wavelengths that are all the same
(highly saturated) or varying (less saturated).
The Structure of the Eye
Light enters the eye and is focused through the cornea, passes through the
aqueous humour 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 ganglion
and bipolar cells to stimulate the rods and cones.
The Process of Sight and Colour Perception
How the Eye Works
Rods detect changes in brightness but do not see colour, and function best in low
levels of light. They do not respond to different colours and are found everywhere
in the retina except the centre or fovea.
Cones are sensitive to colours and work best in bright light. They are responsible
for sharpness of visual information and are found in the fovea.
Perception of Colour
Trichromatic theory of colour perception assumes three types of cones: red,
green and blue. All colours would be perceived as combinations of these three.
The ABC’s Of Sensations
What Is Sensation?
Sensation is the activation of receptors located in the eyes, ears, skin, nasal
cavities, and tongue.
Sensory receptors are specialised forms of neurons and are activated by
different stimuli such as light or sound.
Sensory Thresholds
A just noticeable difference is the smallest differences between two stimuli that
are detectable 50% of the time.
Weber’s law of just noticeable difference states that the just noticeable difference
between two stimuli is always constant.
Absolute thresholds are the smallest amount of energy needed for conscious
detection of a stimulus at least half the time it is present.
Subliminal stimuli are just below the level of conscious awareness, but have not
been shown to affect behaviour in day-to-day life.
Habituation and Sensory Adaptation
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
Perceptual Properties of Light: Catching the Waves
Brightness corresponds to amplitude of light waves, while colour corresponds to
length of the light waves.
, Saturation is the psychological interpretation of wavelengths that are all the same
(highly saturated) or varying (less saturated).
The Structure of the Eye
Light enters the eye and is focused through the cornea, passes through the
aqueous humour 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 ganglion
and bipolar cells to stimulate the rods and cones.
The Process of Sight and Colour Perception
How the Eye Works
Rods detect changes in brightness but do not see colour, and function best in low
levels of light. They do not respond to different colours and are found everywhere
in the retina except the centre or fovea.
Cones are sensitive to colours and work best in bright light. They are responsible
for sharpness of visual information and are found in the fovea.
Perception of Colour
Trichromatic theory of colour perception assumes three types of cones: red,
green and blue. All colours would be perceived as combinations of these three.
