Sensing the World. Some basic principles.
Sensation – the process by which our sensory receptors and nervous system
receive and represent stimulus energies from our environment.
Perception -- the process of organizing and interpreting sensory
information, enabling us to recognize meaningful objects and events.
Bottom up processing – analysis that begins with the sensory receptors and
works up to the brains integration of sensory information
Top down information – information processing guided by higher level
mental processes as when we construct perceptions drawing on our
experience and expectations.
Psychophysics – the study of relationships between the physical
characteristics and stimuli, such as there intensity and our psychological
experience of them.
Absolute threshold -- the minimum stimulation needed to detect a particular
stimulus 50 % of the time.
Signal detection theory – a theory predicting how and when we detect the
presence of faint stimulus while background stimulus is going on.
Subliminal – below ones absolute threshold for conscious awareness.
Priming – The activation often unconsciously of certain associates
predisposing ones perception memory or response.
Difference Threshold – minimum difference between two stimuli requiring for
detect• Weber’s Law – to be perceived as different, two stimuli must differ
by a constant minimum by a constant minimum percentage.
Sensory Adaptation – diminished sensitivity as a consequence of constant
▯ Transduction – the conversion of one form of energy into another.
Light enters through the CORNEA!
CORNEA protects the eye and bends light to focus.
THEN THE LIGHT PASSES THROUGH THE PUPIL – small adjustable opening
surrounded by the IRIS which is a colored muscle that adjust light intake.
It dilates or constricts in response to inner emotions or light intensity.
Behind the pupil is the LENS which focuses incoming light rays into an
image. And then the image goes on into the RETNA which is multy layer
tissue on the eyeballs sensitive inner surface.
The LENS focuses the rays through a process called accommodation where it
changes shape to focus objects near or far.
▯ The Retina
Light enters the outer layers of the retina and burries into receptor cells
known as rods and cones.
Rods – blacks whites and greys (peripheral and twilight vision)
Cones – near the center .. daylight or well light conditions (give detail and
give rise to color)
CONES—CLOWN HAT.. COLORFUL.. VERY DETAILED. CENTER OF THEIR
HEAD. HATE DIM LIGHT.
RODS – SHOWER ROD .. WHITE OR GRAY NOTHING CRAZY.
Fovea – central point of the retina
• The cones cluster around it..
▯ OPTIC NERVE – carries info to the brain!
Blind spot .. where the optic nerve leaves the eye, there is a blind spot.
• No receptor cells.
Place Theory says that links the pitch we hear with the place where
the cochlea membrane is stimulated.
Frequency theory – the rate of nerve impulses traveling up the
auditory nerve matches the frequency of a tone thus enabling us to
sense its pitch – LOW PITCHES!
Hearing loss –
conduction hearing loss is hearing loss caused by the damage
mechanical system. That conducts sound waves to the cochlea.
sensory neural -- hearing loss by damage to receptor cells to
Cochlea implant – concerting sounds into electrical signals and
through electrodes threaded through the cochlea.
skin has specific nerve ending in the skin ..