Sensation and Perception

In vision, what is the process of accommodation?

Behind the iris, muscles change the shape of the lens -- flattening it to focus on distant objects and thinkening it to focus on closer objects.

Explain why afterimages occur.

Occurs when receptors are overworked and become dulled to the color, so they want to see the opposite

Explain the gate theory of pain. What things can open or close the "gate"?

A neuron senses pain, and a "gate" in the spinal cord will open or close depending on if it wants us to feel pain.Pain signals are transmitted by small-diameter nerve fibers, which can be blocked at the level of the spinal cord (prevented from reaching the brain) by the firing of larger sensory nerve fibers. Thus sensory nerve fibers can "close a gate" and prevent or reduce the perception of pain.Also intense concentration can dull or prevent pain.

Describe absolute thresholds, difference thresholds, and Weber's law

Absolute threshold: The minimum intensity of stimulation that must occur before you experience a sensation Difference threshold: the just noticeable difference between two stimuli. (i.e. if you're reading a book and watching tv, the amount the volume needs to change for you to notice) Wever's law: The just noticeable difference between two stimuli is based on a proportion of the original stimulus rather than on the fixed amount of difference. (If you had one candle you would notice the change in brightness if you add another, but you wouldn't notice if they added one more to a group of 100 candles.)

In audition, what characteristics of the sound waves determine intensity and pitch?

Amplitude determines intensity, and frequency determines pitch.

How are sound waves converted into neural activity in the brain? What role do the following parts of the ear play in this conversion? auditory canal, eardrum, ossicles/piston, cochlea, oval window, basilar membrane, hair cells, auditory nerve.

Auditory canal: sound goes in through here Eardrum: Sound drums makes this vibrate. Ossicles/piston: The eardrum's vibrations causes the ossicles to vibrate, moving the pisotons Cochlea: Pressure waves in the inner ear's fluid bends hair cells Basilar membrane: Nerons on this fire neural signals to... Auditory nerve: converts sound into perception, allowing you to hear things.

What is a feature detector? What is lateral inhibition? How does lateral inhibition explain the effect of the Hermann grid?

Feature detector: Certain cells that are designed to recognize certain images. Lateral inhibition: an object always looks lighter against a darker background.

Know the basics regarding the stimulus for vision (light) -- i.e., what characteristics of light determine what we see?

Hue is color, and decided by wavelength Brightness is decided by energy. This is also known as amplitude.

Describe common monocular and binocular depth cues.

Monocular depth cues: Occlusion: a near object blocks an object that is farther away Relative size: farr=off objects project a smaller retinal image than close objects do. Binocular depth cues: A cue of depth perception that arise from the fact that people have two eyes. A major cue is the different images the two eyes see.

What causes nearsightedness and farsightedness?

Nearsightedness: The cornea is deformed so that the image occurs in front of the retina Farsightedness: When the image is formed behind the redina

Describe the role of human judgement in signal detection theory. What are the four outcomes in a trial of a signal detection experiment? How could response bias affect these outcomes?

People could potentially convince themselves that they detected a stimulus even when they did not, due to the fact taht they feel that they should have felt/heard/saw something. Hit, Miss, False Alarm, Correct rejection. Response bias means that people are more likely to report seeing a signal when they in fact did not.

Be able to explain/give an example of the following Gestalt principles as they apply to vision: proximity, closure, similarity, good continuation, common movement.

Proximity: If things are close to eachother, you assume they are part of the same image Closure: When your brain fills in gaps, like the dog made out of spots Similarity: You see things as the same if they are similar looking Good continuation: When things intersect, we see them as part of the same thing Common movement: When things move in the same direction at the same rate, we group them together.

What is the difference between qualitative and quantitative sensory coding?

Qualitative: different types of stimuli (i.e. red or green) Quantitative: speed of neutrons (i.e. loudness or brightness)

Know the basics of eye anatomy and be able to identify the role each part of the eye plays in vision: sclera, cornea, iris, pupil, lens, retina, rods and cones, bipolar cells, ganglion cells, optic nerve, blind spot, fovea. What are the differences between rods and cones?

Sclera: White, elastic, outer part of the eye Cornea: The transparent protective outer layer of the eye Iris: The thin, colored outer part of the pupil that controls its size. Pupil: The black circle in the middle of the eye that allows light into the retina Retina: The light sensitive tissue outlining the innermost part of the eye. Rods: Parts of the eye that allow you to see black and white things and are very sensitive Cones: Parts of the eye that allows you to see in color and aren't very sensitve Bipolar cells: Part of the retina that has two extentions Ganglion cells: Transmits images to the brain Optic nerve: Made up of ganglion cells, transmits information to the brain Blind spot: The part of your field of vision the eye can't see. Fovea: responsible for vision based activities such as reading, driving, or watching anything

How are sensation and perception different? What is sensory coding?

Sensation and perception are different because sensation is just what happens to you, and perception is how your brain makes sense of it. For example, words are just shapes, and thus are sensation, but acually reading them is perception. Sensory coding is our sensory organs' translations of stimuli's physical properties into neural impulses.

Explain the basic process of sensory adaptation and give an example.

The reduction/disappearance of certain stimuli over time if there is constant exposure. For example moving to a bad smelling city.

Explain the trichromatic theory of color vision and the opponent-process theory and why both are necessary to understand color perception.

Trichromatic: There are three types of cones, red, green, blue Opponent-process theory: your brain sees all colors as antagonists, such as Red/Green