1.6 Sensation Flashcards
Sensation
The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.
The brain receives input from the sensory organs.
absolute threshold
The absolute threshold refers to the minimum level of stimulus intensity needed to detect a stimulus half the time.
Just noticable difference
Difference threshold refers to the minimum difference (in color, pitch, weight, temperature, etc) for a person to be able to detect the difference half the time.
Sensory adaption
our senses tune out a constant stimulus, we focus on more important incoming information, sensory cells fire less.
The rock in your shoe or the ticking of a clock are more difficult to sense after a while.
Your eyes adapt to darkness
We adapt to the cold water
Webers law
refers to the principle that for two stimuli to be perceived as different, they must differ by a constant minimum percentage and not a constant amount (e.g. 1/100th of the weight, not 2 ounces).
Sensory interaction
occurs when different senses influence each other.
For example:
a burst of sound makes a dim light source more visible.
flavor is an experience not only of taste, but also of smell and texture.
seeing text or lip movement, or even feeling the puff of air from consonants, affects what words we hear.
Synaesthesia
is a condition when perception in one sense is triggered by a sensation in a DIFFERENT sense.
For example– “the number 7 gives me a salty taste” or “rock music seems purple.”
Retina
a layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.
Transduction
the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain.
Blind spot
There is an area of missing information in our field of vision known as the blind spot. This occurs because the eye has no receptor cells at the place where the optic nerve leaves the eye.
To test this, walk slowly up to the screen with one eye closed and the other eye fixed on the dot, and one of the phones will disappear.
Optic nerve
Responsible for transmitting visual information
Once neural signals enter the optic nerve, they are sent through the thalamus to the visual cortex.
Lens
focuses and flips upside down (Candle)
Accomidation
The lens is not rigid; it can perform accommodation by changing shape to focus on near or far objects.
Nearsightedness
Close objects clear far blurry eyeball is too longe the lense focuses the images in front of the retina
Farsightedness
Far objects clear close are blurry eyeball too short lense focuses image behind the retina
Rods
help us see the black and white actions in our peripheral view and in the dark. Rods are about 20 times more common than cones,
Cones
help us see sharp colorful details in bright light.
Fovea
Point of central focus
Trichromatic theory
there are three types of receptor cones that respond to–red (long), green (medium), and blue (short) wavelengths. All the colors we perceive are created by light waves stimulating combinations of these cones.
Opponent process theory
refers to the neural process of perceiving white as the opposite of perceiving black; similarly, yellow vs. blue, and red vs. green. After images occur when certain ganglion cells are activated while others are not
Ganglion cells
specialized neurons located in the retina at the back of the eye. They receive signals from bipolar cells and transmit them through their axons, forming the optic nerve which carries visual information to the brain.
Afterimages
A flash of light prints a lingering image in your eye. After looking at something bright, such as a lamp or a camera flash
Dichromatism
when only two cone types are functional typically lacking a red-green cone
Monochromatism
monochromacy (monochromatism), when none or only one type of cone receptor is functional.
