Week 6 Flashcards
Corollary Discharge Theory
Definition: movement perception depends on three signals:
Motor, Corollary discharge, image displacement
Motor signal (MS)
signal sent to eyes to move eye muscles
Movement is perceived when ____ (an evaluation unit) receives either a ___, ____.
comparator; CDS; IDS
Corollary discharge signal (CDS)
identical copy of the motor signal
○ Informs the brain about the intentional eye movement.
Image displacement signal (IDS)
movement of image stimulating receptors across the retina.
Movement is perceived when we have either CDS or IDS. T or F
T
STS Superior Temporal Sulcus
Biological motion is processed by sts and ffa
Evidence for sts
Transcranial magnetic stimulation (TMS) applied to STS caused a decrease in ability to detect biological motion.
● Result: This temporary lesion interrupted brain functioning and decreased accuracy on the task.
Sound
Sound is the experience we have when we hear.
Physical definition of sound
● Sound is pressure changes in the air (or other medium).
● Condensation: Higher levels of local air pressure.
● Rarefaction: Decreased regions/ Lower levels of air pressure.
● Sound wave: The pattern of changes in pressure across a space.
Timbre
- “quality” of a sound
- allows us to distinguish between different musical instruments playing the same pitch at the same loudness.
Perception of timbre is influenced by
Attack: how quickly a note reaches its maximum volume after being played
- Fast attack (piano note) sounds more abrupt vs. Slow attack (bowing of a violin) sounds more gradual
Decay: How quickly the sound diminishes after the initial peak
- Guitar string (rapid decay) vs. Organ (long decay)
Different harmonics: Different instruments have different harmonic content for the same pitch
Pure tones
- Perceived as a single note without any harmonics or overtones
- Simplest form of a sound wave
Complex tones:
- A combination of multiple frequencies with various harmonics or overtones
- Give the tone its timbre
Additive Synthesis:
- Constructs complex tones by adding together pure tones at different frequencies
Signal Decomposition
Fourier Analysis: breaks down a complex waveform into a series of sine waves
that sum up to the original waveform.
Fundamental frequency
- The lowest frequency in a complex tone
- Determines the pitch of the note
Missing Fundamental Effect
- Perceived pitch: periodicity pitch; when a harmonic or the fundamental frequency is lost, the perceived pitch remains the same due to the effect of the missing fundamental.
- Consistent fundamental frequency
- The spacing of the harmonics and the repetition rate of the waveform carry the pitch information related to the fundamental frequency.
Audibility Curve
- The minimum sound pressure level that the average human ear can detect at each frequency
- Humans are most sensitive to sounds in curve dips in the 2-5 kHz range
Equal Loudness Curves:
- A set of curves that illustrate the ear’s sensitivity to different frequencies at various loudness levels
- The ear is less sensitive to very low and very high frequencies.
In the sound stimulus, greater condensation of air molecules would correspond to
higher amplitude
If a sound level meter measures 0 decibels (dB), this means no sound signal is present.
False
The decibel scale relates physical pressure in the sound wave to the psychological experience of loudness. This scale demonstrates ____________________ as we attempt to estimate the magnitude of the physical stimulus.
response compression
Perceived tone height corresponds to which of the following physical dimensions of sound?
Frequency