Chapter 5 - Sensation & Perception Flashcards
Describe the difference between bottom-up and top-down processing.
Bottom-up: perception based on physical attributes of the stimulus.
Top-Down: perception based on prior knowledge and expectations of the stimulus.
What is an absolute threshold?
The minimum intensity of stimulation that must occur before you experience a sensation 50% of the time.
What is a difference threshold?
The smallest difference between two stimuli that you can notice.
ex: you hear a tone, then you notice an increase in the tone’s volume.
What is Weber’s law?
The difference threshold is proportional to the original threshold of the stimulus (if you have a 1 oz feather and a 2 oz feather, the difference is more noticeable, than a 5 pound rock and 5 pound and 1 oz rock)
- the more intense the stimulus, the higher the difference threshold
What are the four possible outcomes in a trial of a signal detection experiment? How could response bias affect these outcomes?
Hit
Miss
False Alarm
Correct Rejection
In audition, what characteristics of the sound wave determine intensity/loudness and pitch?
- Amplitude
- Frequency
How are sound waves converted into neural activity in the brain?
What is temporal coding vs. place coding?
How do humans localize sound?
Describe the two different types of nerve fibers for pain.
Fast fibers - sharp, immediate pain (ex: touch a hot skillet)
Slow fibers - chronic, dull, steady pain (ex: tingly feeling your hand has after you burned it, keeps us from using the injured body part)
Explain the gate control theory of pain.
We experience pain when pain receptors are activated and a neural “gate” in the spinal cord allows the signals through to the brain. Sometimes, sensory nerve fibers can “close a gate” and prevent or reduce the perception of pain.
How are sensation and perception different?
Sensation - the detection of physical stimuli. (ex: you smell something in the hallway)
Perception - the process by which the brain organizes and interprets the sensory information that is detected. (ex: you interpret the smell as pizza)
What is sensory coding?
Explain the basic process of sensory adaptation and give an example.
Sensory adaptation is when there is a disappearance of sensory responsiveness when stimulation is unchanging (not a threat).
ex: The air conditioner has been on for half an hour while you are studying that you do not notice the sound anymore.
Know the basics regarding the stimulus for vision (light) – i.e., what characteristics of light determine what we see?
What does the sclera do?
The white visible part of your eyes. It reflects light back out.
What does the cornea do?
Does about 2/3 of the eye’s focusing. Some incoming light comes through the cornea.
What does the iris do?
Makes eyes the color they are. Controls how dilated the pupil is.
What does the pupil do?
The pupil allows some incoming light and its the opening of the lens.
What do the lens do?
Does the rest of the eyes’ focusing. Does so by changing the shape to focus incoming light rays (accommodation).
What does the retina do?
Located at the back of your eyeballs, has rods and cones which turn light into neural signals
What do the rods and cones do?
Rods and cones are receptor cells.
What do the bipolar cells do?
Bipolar cells send sensory information to ganglion cells.
What do the ganglion cells do?
The axons of the ganglion cells form the optic nerve.
What is the optic nerve?
The optic nerve exits the eye at the back of the retina to the brain (thalamus).
What is the blind spot?
You cannot see in this spot, there are no rods and cons.
What is the fovea?
Near the retina’s center where cones are densely packed.
What are the differences between rods and cones?
Rods
- 120 million rods
- primarily used for night vision (high sensitivity)
- don’t support color vision
- not good for fine details
- located at the periphery of the retina
Cons
- 6 million cones
- primarily used for vision under brighter conditions (during the day) (low sensitivity)
- support color vision
- located near the center of the retina (fovea)
- good for detail
What causes nearsightedness and farsightedness?
Nearsightedness - By the time light hits your retina, the image is blurry because the light comes into focus too soon.
Farsightedness - When light hits your retina it is blurry because the light would come into focus farther than where your retina is
What is a feature detector?
Explain the trichromatic theory of color vision and the opponent-process theory and how both contribute to our understanding of color perception.
Trichromatic Theory - color vision results from activity in three types of cones. blue- violet (short), yellow- green (medium), red-orange (long). If you stimulate a combination of them, that is how you get other colors.
Opponent-Process Theory - this theory treats pairs of colors as opposing. red/green, blue/yellow, black/white. If we stare at something green for too long, we wear out our green receptors, so then we see sa red afterimage, because our red receptors are not fatigued
Explain why afterimages occur.
The opponent-process theory explains afterimages. Afterimages occur when one type of receptors are fatigued (eg. green) so you see it’s opponent for a few seconds when you look away (eg. red)
- green flag
- blue lady
Define proximity.
Near each other seen as one thing
Define closure.
What your mind does when there are incomplete boarders.
ex: we perceive a circle with a gap as a complete circle
Define similarity.
When two stimulus objects resemble each other seen as one thing
Define good continuation.
We tend to group
ex: when lines intersect, we tend to group them to form continuous lines with minimal changes in direction
Common Fate
When stimulus elements move in the same direction at the same speed we see them as part of one object
