Class Notes (811,225)
Canada (494,571)
Psychology (7,646)
PSYB51H3 (313)


7 Pages
Unlock Document

University of Toronto Scarborough
Matthias Niemeier

PSYB51 Lecture 2 SAQ: Which kinds of psychophysical methods exist? Mention at least four. Describe one of them in more detail. - Signal detection theory  not really - Cross modality matching - Magnitude estimation - Method of constant stimuli - Method of limits - Method of adjustment Method of cross modality matching: having stimuli like sound and light being presented at the same time - perceive magnitude of a sound and match it with another modality. One of the retina’s job is FILTERING  to tell whether something is there or not Light - Is electromagnetic waves - Is both a wave and a tiny particle - Use metaphor of wave when light is “trapping” energy - Use light as a particle when thinking of it as a photon, when it is hitting a surface and being absorbed; resulting in sensory transduction - It is the small range of electromagnetic waves Light can be: - Absorbed: energy that is taken up and not transmitted at all. Eg, dust, surfaces, filters (to some extent, they absorb light) - Diffracted: happens whenever waves pass through an aperture or encounter some sort of an obstacle; bending of light or having waves that are spread out o Eg. When you take a photo or when looking at the sun and there is a rainbow - Reflected: energy that is redirected when it strikes a surface o Eg. The ways light gets reflected by the cornea - Transmitted: energy that is encountering a surface and is transmitted in some form that is not called reflection of absorption o Eg. Getting transformed into electrical energy - Refracted: when energy is altered as it passes into another medium o Eg. When a pencil is put in water it looks as if it is bended o Depth of a swimming pool  looks shallower than it is o Rainbows are colorful because light enters a drop of water and the light gets bent as it hits the surface. Then turns into reflection o Refraction is necessary for eye glasses The Human Eye Why is sensing light a “good idea”? - You can find food, gives information about nutrition, helps perceive possible dangers, circadian rhythm: can recalibrate after travelling, Evolution of the Eye - Primitive mechanisms of eye sensing: eye spots o A single protein or cluster on single cells - if you have the setup with a line of photoR and nerve fibres  photoreceptors receive light from everywhere. Everything is completely blurred; not very detailed information - to achieve more spatial vision, it’s a good idea to have a folded area that limits directionality so light can only come from certain directions and not others. The same source of light will still spread light over a large region, so vision is still blurred - “Pinhole” area The human eye is made up of various parts: - Eye is as big as a quarter, but not as durable as a quarter; easily damaged and ages very easily o Aging with vision begins to kick in (peak of its abilities)  8 years o After 8 years you being to lose your acuity o Lens starts to become sclerotic  loses elasticity - Lens attached to ciliary muscles + iris (ring shaped muscle to make pupil smaller  pinhole mechanism), pupil (piece of our body that is just a hole) - Divided into 2 chambers - Aqueous & vitreous humor: vitreous = gel like, inflates the eye - Light is reflected, passes through cornea and gets refracted (has higher density than air) o When jumping in water and opening eyes, it is blurry because its refractive index is much higher than that of our cornea - Pinhole mechanism also helps with vision without refraction - People that are near sighted  when walking into dark room, it is a little blurry Refraction - 4 diff optical components that modulate refraction: cornea, aqueous humor, lens, vitreous humor - Accommodation: biggest part of refraction o Constant - When something is closer to your eye, need more refraction  cornea can’t help; glasses and contacts can help - The lens adds to refraction; the fatter it is, the more refractive power it has - When you have a stretched lens (because ciliary muscles are relaxed, make aperture larger) - When cilliary muscles contract, the aperture gets smaller and the lens relaxes more into its natural state No problems with refraction: a) Emmetropia: no problems with refraction; far light is being bent into a single point b) Myopia: when the eyeball is longer than what refraction is able to o Can be corrected with a concave lens c) Hyperopia: corrected with convex lens, refraction power is too strong because eye is too small d) Astigmatism: cornea is not exactly spherically shaped; light does not get focused properly; gets focused in spots Ophthalmoscope - A way at looking inside of the eye - There is a single spot where everything goes in and out of the eye  optic disk - Hole in retina where we cannot see anything  blind spot - Dark spot = macula (means spot) o Macula is where there is a high density of cones - Neurons of the retina travel to the midbrain, therefore retina is part of the brain - Fundus = back of the eye where the retina is - Fovea has the highest density of photoR but is the thinnest area of the retina Optic disk - Place where ganglion cells, axons and blood vessels enter and exit the eye - Situated on the nasal side of the fovea - Left eye – blind spot on left side; right side on right eye - When something is in blind spot, gets filled in with the background/context of picture Physical light travels through many areas, transduction happens in photoreceptors Photoreceptors: first step of transducing physical things into neural signals - 2 types: o Rods  More specialized for scotopic vision  nighttime  Work best in lower levels of light  90% o Cones  Large range of luminous levels  Daylight rd  Colour vision o 3 photoreceptor: senses info about ligh
More Less

Related notes for PSYB51H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.