Five Senses?There are other senses of which we are unaware or are physiologically separate from the classic senses:

Kinesthetic senses (motor sense)

Proprioception

Muscle stretch

Subsets of Somatosensory

Temperature

Pain

Pressure

Vibration

Vestibular sense

Pheremonal reception? (vomeronasal organ in other animals)

Other animals have different senses that we do not

experience:

Some rodents can see ultraviolet light

Sharks, eels and platypus can sense electrical changes in the environment

Snakes sense infrared (heat)

Bats and Dolphins echolocation

Some birds may use magnetic energy for migration

Sensory TransductionLaw of Specific ‘Nerve Energies’ (Transduction) (Muller, 1826)

- Each sense has dedicated receptors and pathways within brain - Each sense is stimulated by specific physical events (e.g. light, air pressure changes)

The Visual SenseLight – consists of quanta (photons) that vibrate at a particular range in the electromagnetic spectrum

The psychophysics of vision

The visual system breaks down the visual world based on three basic variables:

1. Form

2. Color

3. Motion

1. FormHigher processing involving cortical centers (e.g. inferior temporal lobe damage results in prosopagnosia – the inability to recognize faces with preserved perception of facial features, see Fruit Face)

Spatial frequency is primary determinant of form perception

Fruit Face

2. ColorCoded via wavelength of photons

Consists of:

Brightness – created by brain, a relative measure based on context

Hue – subjective “color”

Saturation – depth of color

Blue colors are short wavelengths – Red is long wavelengths

3. Motion

Motion – range of perception is limited to the speed of relevant organisms; probably involves the convergence of cells coding spatial frequency and changes across spatial frequency

The Eye

The Retina

How do we see color?Trichromatic Theory vs. Opponent Process Theory

Three cone types (with different light sensitive opsins) projecting to ‘opponent process’ ganglion cells.

How does information from your eye get to your brain?

Visual information is separated by color, form and motion in the brain

AuditionWhat is sound?

Air pressure changes (vibrations) of a certain frequency that are audible to an organism.

Pressure changes can be varied in amplitude (loudness measured in decibels (dB)) or in frequency (pitch measured in Hertz (Hz)

The Psychophysics of sound

• In ideal circumstances, humans can hear within the range of 20-20,000 Hz

• The frequency range for human speech is 400-4000 Hz

• We tend to lose our ability to hear higher frequencies as we get older

• Other species can hear outside the range of human hearing

The anatomy of audition

Transduction occurs in the cochlea

Pitch is determined by the location of the basilar membrane most vibrated and the number of hair

cells activated• Place Theory• Volley Theory

How does information get from your ear to your brain?

Which vehicle appears to be larger? Why?