PSYCH-UA 22: Perception
55 flashcards · Psychology · by bkenol
Psychophysics
The branch of perception that quantifies perceptions of physical stimuli.
Psychophysical Techniques
Magnitude Estimation Matching Detection / Discrimination
Ernst Weber
(1795 - 1878) German physician who discovered the smallest change in a stimulus.
Weber's Law
Smallest change in a stimulus that can be detected is a constant proportion of the stimulus level. DL / S = K
Detection Experiment
The subject's task is to indicate whether they perceive something rather than nothing.
Absolute Threshold
The point at which someone can perceive something rather than nothing.
Discrimination Experiment
Task is to indicate which stimulus has a greater intensity (brighter, louder, etc.)
Difference Threshold
Just noticeable difference (JND) or Difference Limen (DL)
Methods of Limits
Absolute Threshold, a series of yes's until you get a no, or vice versa. (Can be yes until no or no until yes)
Presbycusis
Deterioration of hearing due to age
Presbyopia
Deterioration of sight due to age
Methods of Constant Stimuli
Same as limits but the order is randomized. (Due to concerns of bias/criterion, attentiveness, strategy, artificial cues, and history of stimulation)
Stimulus
Intensity of a physical feeling (X-axis)
Forced Choice
Present signal on some trials, no signal on other trials (catch trials). Must respond yes there is a thing or no there isn't.
Gustav Fechner
(1850) Mathematically extended Weber's Law to make it more universal. Founded Psychophysics
Intrinsic Light
(dark light) Spontaneous sense of dim light caused by residual retinal signals arising in the complete absence of light stimulation
Criterion Shift
Shift what constitutes a "yes" or "no"
Information
Sensitivity and competence in an area
Criterion
What makes you say "yes" or "no". Different people may have different biases.
External Noise
Physical noise superimposed on the stimulus of interest. (Smudge on x-ray)
Internal Noise
Noise in the radiologist's brain (neural noise, attention conflict)
Internal Response
The state of mind of the subject that corresponds to the sense of how likely a tumor is present.
Steven's Power Law
Internal response to a stimulus can be quantified as a number*
Signal Detection Theory
When presented with a stimulus, a number will present itself as a measurement that will average at one point with minor variance.
Discriminability (d')
The amount of overlap the Criterion have d' = 1 (lots of overlap) d' = 3 (not much overlap)
Principle of Representation
Everything we perceive is not based on direct contact with an object, but rather from representations formed by sensory receptors and the nervous system.
Transduction
The process in which information is transferred from one type of energy to another.
Visual Form Agnosia
Damage to their brain that causes an inability to recognize objects.
Bottom Up (or Data-Based) Processing
Based solely on the information reaching receptors, only incoming signals.
Top Down (or Knowledge-Based) Processing
Using past experiences or prior knowledge to identify what is being experienced. Filling in the gaps or missing information for easier perception. (Dreaming is entirely Top-Down)
Amplitude
Sound pressure level (Related to loudness)
Sound Intensity in dB
dB SPL = 20log10(PIPref) (Sounds over 85 dB can cause damage)
40 dB earplugs attenuate sound by what factor?
100
Optimal Frequency Range for Human Hearing
1-2 kHz
Pinna
Exterior floppy part of the outer ear
Tympanic Membrane (Eardrum)
Receives air pressure waves High pressure pushes it in Low pressure pushes it out
Malleus, Incus, Stapes
Deliver mechanical signals to the inner ear
Semicircular Canal
Inside the cochlea, where the transduction occurs
Pinna and Eardrum
Directional microphone
Middle Ear
Impedance matching and overload protection
Oval Window
Membrane inside Middle Ear that leads to the Inner Ear
Malleus and Incus
Reduces input of sound by expanding and contracting to change surface area (pressure = lbs/in2)
Inner Ear
Frequency Analysis
Auditory Canal
Tube-like 3 cm long structure that protects the Tympanic Membrane at the end of the canal. Amplifies frequencies between 1,000 and 5,000 Hz. Acts as Band Pass.
Conduction Loss
A form of hearing loss from a disorder in the outer or middle ear, usually involving an overall loss in sensitivity at all sound frequencies.
Bone Conduction
Transmission of sound wave vibrations through bones of the skull to the cochlea. A procedure for testing the integrity of the cochlea in the presence of middle-ear damage.
Sensory/Neural Loss
Hearing loss originating within the inner ear or auditory pathways. May involve selective loss of sensitivity to a limited range of frequencies. Conduction Loss
Cochlea
A cavity inside our ear that connects to the Stapes that modulates pressure waves.
Organ of Corti
Inside Cochlea, houses neurons in mid Cochlea
Cilia
Inside Cochlea, within the Organ of Corti, little hair cells that move and change voltage to create sound.
Outer Hair Cells
Inside Cochlea, within the Organ of Corti, part of a feedback loop where it connects auditory nerve fibers to the Cilia
Basilar Membrane
Within the Cochlea, where the Organ of Corti rests
Noise Stimuli
Sound that doesn't seem like it has a pitch. Width corresponds with amount of noise.
Critical-Band Masking Experiment
When asking a tone, adding gradually more energy, and how much intensity it must have for someone to choose the right interval 75% of the time. Louder noise gradually recruits more neurons. Consists of making wider bands, but less intense. Weber's Law
Critical Bands
Local, cooperative processing of frequency information.