Chapter 2: Sensation and Perception Flashcards
Sensation
aligned with transduction, which means seeing the physical, electromagnetic, auditory, and other information from our internal and external environment and converting this information into electro signals in the nervous system. Raw signal, which is unfiltered and unprocessed until it enters the central nervous system.
Perception
Refers to processing this information within the central nervous system in order to make sense of the information significance. It helps us make sense of the world.
Sensory receptors.
Neurons that respond to stimuli by triggering electrical signals that carry information to the central nervous system.
Proximal Stimuli.
Sensory stimulating byproducts
distal stimuli
Physical objects outside of the body.
Psychophysics
The relationship between the physical nature of stimuli and the sensations and perceptions these stimuli evoke.
Ganglia
Collections of neurons, cell bodies found outside the central nervous system.
Projection areas.
Electrical chemical energy is sent along neuropathways to various projection areas.
Photoreceptors
Respond to electromagnetic waves in the visible spectrum.
Mechanoreceptors
Respond to pressure or movement.
Nociceptors
Respond to painful or nauseous stimuli.
Thermal receptors.
Respond to changes in Temperature.
Threshold
The minimum amount of stimulus that renders a difference in perception.
Osmoreceptors.
Respond to the osmolarity of the blood.
Olfactory receptors.
Respond to the volatile compounds.
Taste receptors.
Respond to dissolved compounds.
Action potentials.
All sensory information is sent to the central nervous system in the form of action potentials, which the central nervous system must then interpret and act upon.
Threshold of conscious perception.
This lack of conscious perception may be because this stimulus is too subtle to demand our attention. The level of intensity that a stimulus must pass to be consciously perceived. Information that is received by the central nervous system but that does not cross this threshold is called subliminal perception. Stimulus below the absolute threshold will not be transduced, and thus never reaches the central nervous system. A stimulus below the threshold of conscious perception arrives at the central nervous system but does not reach the high order brain regions that control attention and consciousness.
Absolute threshold.
Minimum Of stimulus energy that is needed to activate a sensory system. It is the minimum intensity which stimulus will be transduced.
Difference threshold OR just noticeable difference
Refers to the minimum change in magnitude required for an observer to perceive that two different stimuli are different.
Discrimination testing.
In a comment discrimination testing experiment, a participant is presented with a stimuli. The stimulus is then varied slightly and researchers asked the participant to report whether they perceive a change period. Often, the difference continues to be increased until the participant reports they noticed the change, and this interval is recorded, as should the just noticeable difference.
Weber’s Law.
He’s credited with the observation that differences thresholds are proportional and must be computed as percentages.
Signal detection theory.
studies how internal and external factors influence thresholds. During each trial, families may or not be presented. Trials in which the signal is presented are called noise trials, whereas those in which the trial is not presented are called catch trials.
A hit is a trial in which the signals is presented and the subject correctly perceives the signal; And miss is a trial in which the subject fails to perceive the presented signal. A false alarm is a trial in which the subject indicates perceiving the signal, even though the signal was not presented; A correct negative is a trial in which the subject correctly identifies that no signal was presented.
Adaptation.
Our ability to detect a stimulus can change over time. Adaptation can have both the psychological component and Physiological Component. It is one way the mind and body try to focus attention on only the most relevant stimuli, which are usually changes in the environment around us.
Vision
The only sentence to which an entire lobe of the brain is devoted, the occipital lobe.
Eye
Specialized organ used to detect light in the form of photons.
Sclera
Thick structural layer or the white in the eye
The eye is supplied with nutrients by two sets of blood vessels:
Choroidal vessels and retinal vessels
Retina
The innermost layer of the eye, It contains the actual photoreceptors that transduce light into electrical information the brain can process.
Cornea
The clear, doom like window in the front of the eye, which gathers and focuses the incoming light.
Anterior chamber.
Lies in front of the iris.
Posterior Chamber.
Between the iris and the lens.
Iris
Colored part of the eye, is composed of two muscles: dilator pupillae, which opens the pupil under sympathetic stimulation; And the constrictor pupillae, which constricts the pupil under parasympathetic stimulation. The iris is continuous with the choroid, which is a vascular layer of connective tissue that surrounds and provides nourishment to the retina.
Ciliary body.
Produces the aqueous humor that baits the front part of the eye before draining into the Canal of Schlemm.
Lens
Lies right behind the iris and helps control the refraction of the incoming light.
Accommodation
As the muscles contract, it pulls on the suspensory ligaments and changes the shape of the lens to focus on the image as the distance varies.
Vitreous humor.
Transparent gel that supports their retina.
Duplexity or duplicity theory of vision.
States that the retina contains two kinds of photoreceptors: those specialized for light and dark detection and those specialized for color detection.
Cones
Are used for color vision into sense fine details. Most effective in bright light incoming 3 forms: Short also called blue, medium also called green, and long also called red.
Rods
They are used in reduce illumination. Are more functional than cones because each rod cell is highly sensitive to photons and in somewhat easier to stimulate than a cone cell. All rods contain only a single pigment called rhodopsin. Route only allows sensation of light and dark, period. Less useful for detecting fine details because rods are spread over a much larger area of the retina. There are more rods than cones in the human eye.
Macula
The central section of the retina. It has high concentrations of cones.
Fovea
Center most region of the macula. It contains only cones.
Blind spot.
Some distance away from the center of the retina, the optic nerve leaves the eye. This region of the retina which is devoid of photoreceptor is called the optic disc and it gives rise to a blind spot.