pheromones are not smells pheromones are chemical signals sent from one animal to another pheromones
Post on 22-Dec-2015
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TRANSCRIPT
• 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
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 !
Fun
Facts
about
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
Pheromones
Sensory Systems: Auditory
What do we hear?
• Sound is a compression wave:
When speaker is stationary, the air is uniformly dense
Speaker Air Molecules
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:
The speaker moves back leaving an area with less air behind - called rarefaction
CompressionRarefaction
What do we hear?
• Sound is a compression wave:
Speaker
The speaker moves forward again starting the next wave
Compression
Rarefaction
What do we hear?
• Sound is a compression wave - it only “looks” like a wave if we plot air pressure against time
time ->
Air Pressure
Period - amount of time for one cycle
Frequency = number of cycles per second (1/Period)
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
Ear Drum
Oval window
Sensing Vibrations
• Middle ear turns compression waves into mechanical motion
Ear Drum
Oval window
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