Sensory Perception Flashcards
Binocular Cues
This gives them retinal disparity. Eyes are ~2.5 inches apart which allows humans to get slightly different views of objects of world around. Gives humans an idea on depth.
Convergence
- Gives humans an idea of depth as well based on how much eyeballs are turned.
- Gives humans a sense of depth.
- Things far away – muscles of eyes relaxed.
- Things close to us – muscles of eyes contract.
Monocular Cues
- These give humans a sense of form of an object.
- Can infer with one eye.
- The closer an object it is perceived as being bigger.
Interposition (overlap)
- Perception that one object is in front of another.
- An object that is in the front is closer.
Relative Height
Things higher are perceived to be farther away than those that are lower.
Shading and Contour
- Using light and shadows to perceive form depth/contours
- Example: crater/mountain.
Motion Parallax
“relative motion” Things farther away move slower, closer moves faster.
Size Constancy
One that appears larger because its closer, we still think it is the same size.
Shape Constancy
- A changing shape still maintains the same shape perception.
- Example: a wall frame that is hanging off the wall still looks like a rectangle.
Color Constancy
Despite changes in lighting which change the image color falling on our retina, we understand (perceive) that the object is the same color.
Sensory Adaptation
Our senses are adaptable and they can change their sensitivity to stimuli.
Hearing Adaptation
- Inner ear muscle: higher noise = muscle contract
- Takes a few seconds to kick in! So does not work for immediate noises like a gun shot.
- Example: rock concert for an entire afternoon
Touch
Temperature receptors desensitized over time.
Smell
Desensitized receptors in your nose to molecule sensory information over time.
Proprioception
Is the sense of the position of the body in space. Example: “sense of balance/where you are in space.”
Sight
Down regulation or up regulation to light intensity.
Down Regulation
- Light adaptation.
- When it is bright out, pupils constrict and the desensitization of rods and cones.
Up Regulation
- Dark regulation.
- Pupils dilate-, rods and cones start synthesizing light sensitive molecules
Weber’s Law
- 2 vs. 2.05 lb weight feel the same.
- 2 vs. 2.2 lb weight difference would be noticeable.
- ΔI (JND)/I (initial intensity) = k (constant)
- Example: 0.2/2 = 0.5/5 = 0.1, change must be 0.1 of initial intensity to be noticeable
Just Noticeable Difference (JND)
The threshold at which you’re able to notice a change in any sensation.
Absolute Threshold of Sensation
The minimum intensity of stimulus needed to detect a particular stimulus 50% of the time. Some will detect it , others won’t.
Difference Threshold
That’s the smallest difference that can be detected 50% of the time.
Factors of the Absolute Threshold
- Expectations – ex. Are you expecting a text.
- Experience (how familiar you are with it) – ex. Are you familiar of the phones text vibration sound.
- Motivation – ex. Are you interested in the response of the text
- Alertness – Are you awake our drowsy. Ex. You will notice text if you are awake
Somatosensation (Types)
- Temperature (thermoception)
- Pressure (mechanoception)
- Pain (nociception)
- Position (proprioception)
Intensity of Somatosensation
How quickly neurons fire for us to notice. Slow = low intensity Fast = high intensity.
Neuron Timing (Types)
- Non-adapting- neuron consistency fires at a constant rate.
- Slow-adapting - neuron fires in beginning of stimulus and calms down after a while.
- Fast-adapting - neuron fires as soon as stimulus start…then stops firing. Starts again when stim stops).
Vestibular System (Inner Ear)
Focus on inner ear - in particular the semicircular canals (posterior, lateral, and anterior; each orthogonal to each other)
Endolymph
When we rotate the fluid shifts in the semicircular canals – allows us to detect what direction our head is moving in, and because we can detect how quickly the endolymph is moving we can determine the strength of rotation.
Otolithic Organs
- Help us to detect linear acceleration and head positioning.
- Example: In these are CaCO3 (Calcium carbonate) crystals attached to hair cells in viscous gel. If we go from lying down to standing up, they move, and pull on hair cells, which triggers AP. These would not work very well w/o gravity! Buoyancy can have effects as well, particularly without visual cues on which way is up/down.
Signal Detection Theory
Looks at how we make decision under conditions of uncertainty – discerning between important stimuli and unimportant “noise”.
Role of Signal Detection Theory in Psychology
- Imagine being given a list.
- Then a second list.
- Now experimenter asks, which words on the second list were on the first.
- Person has to have uncertainty as they are not sure whether a certain word is exact or similar than the one in the first list.
Hit, False Alarm, Correct Rejection & Miss
- Hit: the subject responded affirmative when a signal was present.
- False Alarm: the subject perceived a signal when there was none present.
- Correct Rejection: a correct negative answer for no signal.
- Miss: a negative response to a present signal.
d’: Strength
- Hit > miss (when there is a strong signal)
- Miss > hit (weak signal)
c: Strategy
- Conservative strategy: always say no unless 100% sure signal is present. Bad thing is might get some misses.
- Liberal strategy- always say yes, even if get false alarms.
Strategy B
- Let’s say choose this threshold = 2.
- So anything > 2 will say YES
- Anything < 2 will say NO.
- So probability of hit is shaded yellow, and false alarm is purple.
D Strategy
- D = (d’- B)
- So, let’s say d’ in this example is 1
- 2-1=-1.
- Anything above -1 = YES
- Anything below -1 = NO.