Pheromones
• Pheromones are not smells
• Pheromones are chemical signals sent from
one animal to another
Pheromones
• Pheromones either induce a behavior in
another animal or cause some physiological
change
• Very common in insects...not so common in
mammals...unclear role in humans
Fun Facts about Pheromones
• For example: Androstenone, found in male
pig saliva, causes a female pig to allow the
male to mate with her
Fun Facts about Pheromones
• androstenone is also found in the sweat of
human males!
• Does androstenone (or pheromones in
general) affect humans?
• Design an (ethical) experiment…
Fun Facts about Pheromones
• Kirk-Smith & Booth (1980) sprayed some of
the seats in a dentist’s waiting room with
androstenone
• Compared to a control condition, more
women used the androstenone seat
Fun Facts about Pheromones
• Fewer men used the androstenone seat !
Pheromones
• Other possible ways in which pheromones
influence humans:
– synchronization of menstrual cycles
– mate selection - attraction to opposite major
histocompatibility complex
Pheromones
• Pheromones do not control behavior!
• Human behavior is largely under top-down
influences, but may be affected subtly by
pheromones
• It is unclear whether molecules such as
androstenone even qualify as pheromones they may be just like other odour molecules
Sensory Systems: Auditory
What do we hear?
• Sound is a compression wave:
Speaker
Air Molecules
When speaker is stationary, the air is
uniformly dense
What do we hear?
• Sound is a compression wave:
Speaker
When the speaker moves, it compresses the air in front of it.
What do we hear?
• Sound is a compression wave:
Rarefaction
Compression
The speaker moves back leaving an area with less air behind called rarefaction
What do we hear?
• Sound is a compression wave:
Speaker
Compression
Rarefaction
The speaker moves forward again starting the next wave
What do we hear?
• Sound is a compression wave - it only “looks”
like a wave if we plot air pressure against time
Period - amount of time for one cycle
Frequency = number
of cycles per second
(1/Period)
Air Pressure
time ->
Properties of a Sound Wave
• 1. Amplitude: difference in air pressure
between compression and rarefaction (Sound
Pressure Level)
Properties of a Sound Wave
• 1. Amplitude: difference in air pressure
between compression and rarefaction (Sound
Pressure Level)
– What is the perception that goes along with the
sensation of sound amplitude?
Properties of a Sound Wave
• 1. Amplitude: difference in air pressure
between compression and rarefaction (Sound
Pressure Level)
– What is the perception that goes along with the
sensation of sound amplitude?
LOUDNESS
Properties of a Sound Wave
• 2. Frequency: how many regions of
compression (or rarefaction) pass by a given
point per second (expressed in Hertz)
Properties of a Sound Wave
• 2. Frequency: how many regions of
compression (or rarefaction) pass by a given
point per second (expressed in Hertz)
– What is the perception that goes along with the
sensation of frequency?
Properties of a Sound Wave
• 2. Frequency: how many regions of
compression (or rarefaction) pass by a given
point per second (expressed in Hertz)
– What is the perception that goes along with the
sensation of frequency?
PITCH
Sensing Vibrations
Sensing Vibrations
• Outer ear transmits
and modifies sound
(critical for sound
localization)
Sensing Vibrations
• Middle ear turns compression waves into
mechanical motion
oval window
stapes
Sensing Vibrations
• Middle ear turns compression waves into
mechanical motion
Oval window
Ear Drum
Sensing Vibrations
• Middle ear turns compression waves into
mechanical motion
Oval window
Ear Drum
Compression Wave
Sensing Vibrations
• The cochlea, in the inner ear, is a curled up
tube filled with fluid.
Auditory
Nerve to
Brain
Sensing Vibrations
• Inside the cochlea is the basilar membrane
• Movement of the oval window causes ripples
on the basilar membrane
Sensing Vibrations
• Basilar membrane measures the amplitude
and frequency of sound waves
– amplitude (loudness)
–frequency (pitch)
Sensing Vibrations
• Basilar membrane measures the amplitude
and frequency of sound waves
– amplitude (loudness) - magnitude of displacement
of the basilar membrane
–frequency (pitch)
Sensing Vibrations
• Basilar membrane measures the amplitude
and frequency of sound waves
– amplitude (loudness) - magnitude of displacement
of the basilar membrane
–frequency (pitch) - frequency and location of
displacements of the basilar membrane
Sensing Vibrations
• Basilar membrane measures the amplitude
and frequency of sound waves
–frequency (pitch) - frequency and location of
displacements of the basilar membrane