Week 4 Flashcards
(22 cards)
Sensation vs perception.
Sensation is the process of collecting external energy and converting into neuronal impulses.
Perception is the analysis of sensory information.
How does smell work?
There are hair receptors in the nose, molecules in fluid on mucus in the nose.
How does sound work?
Energy passed through movement of molecules in a medium (e.g. air, water)
What parts of the eye feature in the scleral layer?
Conjunctiva, cornea, extrinsic muscle - outlet white layer helps the eye keep its shape
What parts of the eye feature in the choroid layer?
Ciliary body, lens, pupil, iris - the middle layer supplies the eye with blood
What parts of the eye feature in the retina layer?
Aqueous humour, vitreous humour, blind spot, fovea, optic nerve - the inner layer receives light and sends nervous messages to the brain by way of the optic nerve.
What is the difference between rods and cones?
Cones - used in bright light, work well in centre of the eye (fovea)
Rods - used in low light, cannot give high precision
What are at the back of the retina?
Photoreceptors - rods and cones; they convert photon energy to neural signals
What are the two ways to change response to light levels?
Range = changing the sensitivity of the photoreceptors (light and dark adaptation) Aperture = change the amount of light coming in
How do you reduce blur in the eye?
Cornea and lens bend the light to focus the image.
What is stretching in terms of the eye?
Sensory systems exaggerate differences; brightness, colour, orientation, motion
What are constancies in terms of the eye and sensation?
Sensory systems compare across current (local) experience to account for Global experiences; brightness, colour, size
What are psychophysics?
Measuring perceptions; the method used to systematically measure our perception. Basic psychophysics; detection and discrimination.
What is JND and threshold?
Just noticeable difference; how big the difference has to be for you to notice it is difference = difference threshold.
How do you measure threshold?
Method of limits - start with an intensity that is either below or above threshold; method of constant stimuli - use a number of set intensities and see how the probability of detection changes with intensity.
How can a persons bias influence threshold?
Don’t want to miss any; don’t want to be careless or seem impulsive.
What happens to the signal after it leaves the retina?
Eye - optic nerve - optic chasm - optic tract - lateral geniculate nucleus - primary visual cortex
What is the LGN in the thalamus?
Organises the info from the 2 eyes but keeps them separated; magno - info about where object is sent quickly to the brain; parvo - info about what the object is send slower to the brain
What does the visual area 1 like?
V1 - pulls the image apart, likes lines, objects broken down into basic shapes
What are the three main cell types by Hubel and Wiesel?
Simple cells - basic orientation and some motion; complex cells - orientation and motion; hyper-complex cells - length and orientation and motion
What do the visual areas 4, 5 and IT like?
V4 - basic shape and colour; V5 - motion; IT - complex shape and faces
What do gnostic cells or grandmother cells do?
Adding features together to create image
