Week 9 Flashcards
What is psychophysics?
- Refers to psychological sensations of physical properties of the world
- Fechner and Von Helmholtz’s goal was to measure the relationship between the physical characteristics of the stimulus and the sensory experience
- Helped understand all of perception in terms of elementary sensation
What is the difference threshold?
- Just-noticeable difference between two stimuli
- In all sensory domains, the just noticeable difference threshold goes up as the intensity goes up
What is Fechner’s Law?
Each JND represents an equal step in the psychological magnitude of a sensation which means changes in stimulus can be compared across sensory domains
What is Steven’s Power Law?
The proposed relationship between the magnitude of a stimulus and its perceived intensity or strength
What is the absolute threshold?
- The minimum intensity of stimulation that must occur before we can experience a sensation
- Can only be detected 50% of the time
What are faint signals?
Stimuli not only depends on an individual’s sensitivity but also their expectations
What are Cognitive factors?
A individual’s ability to hear faint signals which involve thought processes, including changes in attention, expectation and alertness
What is response bias?
A person’s willingness to say yes or no with disregard to sensitivity
What is Signal Detection Theory?
Argues that there is no absolute threshold because what is measured as the absolute threshold changes based on the person’s ability to detect it against background noise
What is pitch?
- How high or low we believe a sound to be
o High cycling, changing and alternating frequencies are high pitches - Fundamental frequency is the lowest frequency of a periodic waveform
- Pitch is decoded when the cochlea breaks down sound into their component frequencies
- The presence of each frequency and its intensity are sent to the brain through individual fibres of auditory nerves
- Each nerve is most sensitive to a certain pitch
What is Tonotopic organization (place codes)?
- When frequencies are anatomically separated and organized in the ear
- Organization is maintained all the way to the primary auditory cortex
- Acts as a code which signals which frequencies are present in the sound
What are temporal codes?
- Used for lower-frequency sounds
- Able to be used up to frequencies of 5000 Hz
- Auditory nerve fibres fire quickly and in sync with a stimulating waveform
- Every time there is a compression in the sound wave, the hair cell depolarizes and an action potential is generated
What is the volley principle?
- When sounds have frequencies higher than 1000 Hz but lower than 5000 Hz, fibres take turns creating action potentials
- The sequence must be precise
What are temporal and place codes used for?
Place codes are used for high pitch noises whereas temporal codes are used for lower frequencies
What are complex sounds made of?
Complex sounds are made of multiple components
What is the fundamental frequency?
The lowest frequency component of a sound
What are the elements of sound?
They have the fundamental frequency, harmonics (all of the other components of sound which are multiples of the fundamental)
What is the Timbre of sound?
It is used as pattern recognition to identify particular sound sources
It depends on the relative amplitude of components and discrete parts of the basilar membrane respond to each of the components, detecting their frequencies and amplitudes
What is sound intensity?
It is what we perceive as loudness and is determined by how each auditory
If a sound is intense, then each fibre attached will fire as hard as they can
If the sound is soft, it will fire randomly
What is loudness affected by?
Frequency
What is intensity cue?
Difference in timbre based on location and it is helped by the shape of pinna and outer ears
How is the location of sound inferred?
It is inferred based on the frequency and timing information of the sound
What are the 3 ways we use our ears to locate sound?
1) Pinnae - the shape determines how sounds are transmitted into the ear canal in a way that allows us to find the elevation of a sound source
2) The brain uses timing to determine where the sound comes from
3) Intensity - Head “shadows” sound so they are more intense at the close ear than the far one
Timing and cues are used by different structures early in the auditory neural pathway in the brainstem to determine sound locations
Where would humans be most sensitive to change in sound location?
In the midline but our ability to determine the location of objects through hearing is worse than our ability through touch or vision
What is motion parallax?
The idea that we perceive the world in 3D through a variety of cues
What are the two cues for 3D perception?
monocular depth cues are cues to distance that only depends on one eye
Relative motion is a cue to depth perception