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 Compression Rarefaction

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

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