UNIT 2: SENSATION Flashcards
Sensation
The process that occurs when special receptors in the sense organs are activated, allowing various forms of outside/environmental stimuli to become neural signals in the brain.
Transduction
Stimuli are converted to different neural activity
Synesthesia
“joined sensation.”
A condition in which the signals from the various sensory organs are processed differently, resulting in the sense information being interpreted as more than one sensation.
Can sense different neural activities all at once.
It is a trait rather than a disorder (like eye colors).
A synesthete might not only hear my voice, but also see it, taste it, or feel it as a physical touch.
SENSORY RECEPTORS
Specialized form of neurons found/occurs in the sense
organs: Eyes, mouth, ears, nose, and internal organs.
Sends signals to the brain.
Stimulated by different kinds of energy:
Light, vibrations, pressure, temperature, and chemical substances.
Difference Threshold
difference between two stimuli
Weber’s Law (Enst Weber)
SENSORY THRESHOLDS
Difference Threshold
Absolute Threshold
Difference Threshold
The lowest level of stimulation that a person can consciously detect 50% of the time the stimulus is present.
Gustav Fechner.
Signal Detection Theory
Provides a method for assessing the accuracy of judgements or decisions under certain conditions.
Habituation
When your brain stops attending to constant, unchanging stimuli.
The sensory still responds to the stimulus, but the lower centers of the brain do not send signals to the cortex.
Sensory Adaptation
Sensory receptors become less responsive to a stimulus that is unchanging.
Unchanging information from the sensory receptors is effectively ignored.
STRUCTURES OF THE EYE
Light enters the eye through the cornea and the pupil.
The iris controls the size of the pupil.
The pupil dilates or constricts depending on the light source.
Light passes through the lens of the retina and will be translated to nerve impulses.
Nerve impulses travel to the brain through the optic nerve.
THE VISIBLE SPECTRUM
Light sources.
Allows us to see different colors depending on the intensity and wavelength of light.
ROYGBIV.
REFRACTION
Is when waves of light travel through two different mediums and it bends.
Myopia
Nearsightedness
The eye is elongated, longer than the typical length of an eye.
Hyperopia:
Farsightedness
The eye is short, shorter than the typical eye length.
CROSSING OF THE OPTIC NERVE
Light entering the eyes separates into the left and right visual fields.
Information from these visual fields goes to the contralateral visual cortex.
BLIND SPOT
The area in your retina where the axons of the retinal ganglion cells exit the eye to form the optic nerve is insensitive to light.
Cells in the retina of the eye where the optic nerve connects are not triggered by light, no phtoreceptors.
Dark Adaptation
Occurs when the eye recovers its ability to see when going from a brightly lit state to a dark state.
Light Adaptation
Is the recovery of the eye’s sensitivity to visual stimuli in light after exposure to darkness.
More rapid than dark adaptation.
Adaptation from dark to light.
Rods
Responsible for non color sensitivity to low levels of light.
Activated when adapting to darkness.
MIXING LIGHT
Involves:
Rods
Cones
Cones
Responsible for color vision and sharpness of vision.
Activated when adapting to a well lit room.
COCO: (Cones = Colors)
Trichromatic Theory
Trichromatic: three colors
There are three types of cones and these specific cones can only receive specific wavelengths of light.
Blue = short wavelength
Green = medium wavelength
Red = long wavelength
Afterimages:
images that occur when a visual sensation persists for a brief time even after the original stimulus was removed.
But it is the opposite/inhibited colors from the original stimulus that will appear as an afterimage.
Opponent-Process Theory
Visual neurons are stimulated by light of one color and inhibited by light of another color.
One member of the color pair suppresses the other.
Red vs Green
Blue vs Yellow
Black vs White
explains afterimages
DICHROMATS
They can only distinguish two colors.