MCAT Behavioral Sciences - Sensation and Perception

Sensation

Taking the physical, electromagnetic, auditory and other information from our internal an external environment and converting this information into electrical signals in the nervous system

Perception

Processing information within the central nervous system in order to make sense of the information significant

Sensory Receptors

Neurons that respond to stimuli by triggering electrical signals that carry information to the CNS

Photoreceptor

Respond to electromagnetic waves in visible spectrum (light)

Mechanoreceptors

respond to pressure or movement

Nociceptors

Respond to painful or noxious stimuli (somatosensation

Thermoreceptors

Respond to changes in temperature (thermosensation)

Osmoreceptors

Respond to osmolarity of the blood (water homeostasis)

Olfactory Receptors

Respond to volatile compounds (smell)

Taste Receptor

Respond to dissolved compounds (taste)

Distal Stimuli

Physical objects outside the body

Proximal Stimuli

Photons, sound waves, heat, pressure or other stimuli that directly interact with sensory receptors

Psychophysics

Relationship between physical nature of stimuli and the sensation and perceptions these stimuli evoke

Ganglia

Collection of neuron cell bodies found outside the CNS

Threshold

The minimum amount of a stimulus that renders a difference in perception

Absolute Threshold

Minimum of stimulus energy that is needed to activate a sensory system

Threshold of Conscious Perception

The level of intensity that a stimulus must pass in order to be consciously percieved

Subliminal perception

Information that is recieved by the CNS but does not cross the threshold

Difference Threshold

Minimum change in magnitude required for an observe to percieve that two different stimuli are different

Discrimination testing

Participants presented with stimulus, then varied and report if recieves change

Webers Law

Difference thresholds are proportional and must be computed as percentages

Signal Detection Theory

Studies how internal and external factors influence thresholds of sensation and perception

Noise Trial

In signal detection experiemmnts the trial in which signal is presented

Catch trial

In signal detection experiment the trial where signal is not presented

Hit

Trial in which signal is presented and subject correctly percieves the signal

Miss

A trial fails to percieve the signal

False Alarm

Trial in which subject indicates percieving signal even though there was no signal present

Correct negative

Trial when subject correctly identifies no signal was presented