Chapter 4: Sensation and Perception
What is psychophysics?
Psychophysics is how physical stimuli affect psychological experiences.
What is a threshold?
A threshold is a dividing point between what is detectable and what is not detectable. An absolute
threshold is the minimum amount of stimulation a person can detect.
What is JND?
A just noticeable difference is the amount of stimulation that a sense can detect. It is closely related to
absolute threshold however, it mainly focuses on sense.
Weber’s Law: the size of JND is a constant proportion of the size of the initial stimulus
What is psychophysical scaling?
Flechner’s Law: the magnitude of a sensory experience is proportional to the number of JNDs that the
stimulus causing the experience about the absolute threshold.
What is the SignalDetection Theory?
The signaldetection theory is the detection of stimuli using decision and sensory processes which are
influenced by factors besides stimulus intensity.
What is perception without awareness?
Perception without awareness is called subliminal perception: self explanatory. When senses are being
used but unconsciously.
What is sensory Adaptation?
Sensory adaptation is when the sense become accustomed to the stimulation and declines.
SIGHT: VISUAL SYSTEM
Explain light as a stimulus.
Light is an electromagnetic radiation that travels in waves at the speed of light. The major properties is
purity, wavelength and amplitude.
Explain the components of the eye.
There are 2 main purposes: the channel light to neural tissue and house it.
• Light enters through the cornea and the lens then turns upside down and hits the retina.
• Pupil is the black part of the eye that helps regulate the amount of light passing through.
• The eye moving is called saccades
• Optic disk just a hole in the retina for nerves to get out of the eye.
What are Cones and Rods?
Fovea = cones
• Cones are used for daylight and colour vision
Outside fovea = Rods
• Rods are night vision and peripheral vision What is dark and light adaptation?
Dark adaptation is when eyes become more sensitive to light in low illumination
Light adaptation is when eyes become less sensitive to light is high illumination
How does the retina process information? *
Light the hits the retina sends information through the optic nerve to the brain.
How does visual information get to the brain?
First axons travel to the optic chiasm, then the optic nerve turns to 2 pathways. The main one goes to the
thalamus, the other goes to the midbrain.
How does the visual cortex process information?
After the processing in the visual cortex (occipital lobe) visual information is sent through what (ventral)
and where (dorsal) pathways to other cortical lobes.
What are the multiple methods in vision research ?
What is the stimulus for colour?
Subtractive mixing is removing some wavelengths of light so there is less light then there was before.
Additive is adding more light to the mixture than there was originally. (Shining a colour on a white
What is the trichromatic theory of colour vision?
The trichromatic theory of colour vision is 3 types of receptors with different sensitivities to different
What is the opponent process theory of colour vision?
The opponent process theory of colour vision is that colour perception depends of receptors that make
antagonistic responses to Red Blue and Yellow.
How have the theories been reconciled to explain colour vision ?
Researchers have found that there are 3 types of cones that picks up different wavelengths. As well as the
visual cortex picks up the opposites red and green, blue and yellow.
What are some effects that colour has on behaviour?
Elliot a researched belives that colour has an unconscious