Perception Flashcards
What is psychophsyics?
Psychophysics is a scientific method for investigation of relationships between physical stimuli and psychological which marks the beginning of experimental psychology
What is the absolute threshold?
Absolute threshold is the minimum stimulus detected reliably from no stimulus i.e. detection of difference from zero
What is absolute detection?
Absolute detection is really a special case of difference detection
What is difference detection?
Difference detection wants to establish what increase in intensity is required for people to determine a difference exists between two people
What is a standard stimulus?
Standard stimulus gets people to detect if another comparative stimulus is more than the standard.
What is the difference threshold or ‘Just Noticeable Difference’ (JND) ?
JND is the minimum difference in stimulus intensity necessary to tell two stimuli apart. This depends on the magnitude of the stimuli
What is the Weber - Fechner Law?
Weber - Fechner Law is the change in intensity divided by intensity
What does the Weber-Fechner Law state?
This law states that JND is a constant proportion of standard stimulus intensity
What is the Weber fraction for light intensity, sound intensity and salt taste?
Light intensity- 0.079
Sound intensity - 0.048
Salt taste - 0.083
What do signal detection experiments involve?
Signal detection experiments involve discriminating the presence of a stimulus from background noise
What is visible light?
Visible light is the portion of the electromagnetic spectrum that is seen by humans
What is visual acuity?
Visual activity is the ability to see fine detail
How does light enter the eye?
Light reflected from a surface enters the eye via the transparent cornea bending to pass through the pupil at the centre of the coloured iris
Where is the light focused on the eye?
Light is focused onto the back of the eye, the retina, by a lens that changes shape depending on the distance of the object we are trying to focus upon.
What is the retina made up of?
The retina is made up of 120 million photoreceptors
What are photoreceptors?
Photoreceptors are sensory cells that respond to light
What do photoreceptors do?
Photoreceptors influence the specialised neurons that signal the brain’s visual centres through their bundled axons, which make up the optic nerve
What does the optic nerve do?
The optic nerve creates the blind spot
The retina has a small dip in it called the fovea, what is the fovea?
The fovea is the area responsible for high acuity vision i.e. vision is clearest at the fovea
What are the two types of photoreceptors?
rods and cones
How many types of cones are there and what do they do? and what do they allow us to perceive?
There are three different types of cones that respond to different wavelengths of light which allow us to perceive colour
What is the fovea made up of?
Fovea is made up of cones
What are rods sensitive to and what does this mean?
Rods are more sensitive to light which makes them useful in dark situations. They DO NOT provide info on light
What are the vast majority of our photoreceptors?
The vast majority of our photoreceptors are rods
Photoreceptors also connect to retinal ganglion cells. What do the axons on the retinal ganglion cells form?
Axons of these retinal ganglion cells form the optic nerve. There are no photoreceptors on the retina where the optic nerve is making a blind spot.