Paralegal

Chapter 3: sensation and perception
Sensation: Detection of basic sensory experience of environmental stimuli such as sounds, images and odors. This result from neural impulses transmitted to the brain from sensory receptors stimulated by energy from external environment.
Sensory receptors: Specialized cells unique to each sense organ that responds to a particular form of sensory information.Transduction: The process by which a form of physical energy is converted into a coded into neural signal that can be processed by the nervous system. (Later decoded in perception)
Threshold: The point at which a stimulus is strong enough to be detected because it activates a sensory receptor.
Absolute threshold: the smallest possible strength of a stimulus that can be detected half of thetime
Difference threshold: The smallest possible difference between two stimuli that can be detected half the time; also called just noticeable difference (jnd).
Weber’s law: The jnc will vary depending on its relation to the strength of the original stimulus. However, the law doesn’t account for the psychological experience which is relative.
Subliminal perception: The detection of stimulithat are below the threshold of conscious awareness; non-conscious perception.
Perception: integration, organization, and interpretation of sensory information in a way that’s meaningful.
No clear boundary between the two processes, many called them a single process.

Sensory adaptation: Gradual decline in sensitivity to a constant stimulus. (relative to the duration of exposure)
VisionLight is the energy received by the sensory receptors, it’s one of the many kinds of electromagnetic energy traveling in the form of waves. The different types of electromagnetic energy is based on wavelength (the distance from one wave peak to the another)
The human visual system
Cornea: Clear membrane covering the visible part of the eye. Gathers and directs incoming light
Pupil: Theopening in the middle of the iris that changes size to let different amounts of light in.
Iris: The colored part of the eye, which is the muscle that controls the size of the pupil.
Lens: Transparent structure located behind the pupil that focuses or bends lights as it enters the eye.
Accommodation: The process by which the lens changes shape to focus light so that it fall on the retina.Myopia: distant object are blurry because lights fall in front of the retina
Hyperopia: close objects are blurry because they fall behind the retina
Presbyopia: the lenses became brittle and inflexible
Astigmatism: abnormal eyeball shape results in blurry vision

Retina
Thin, light sensitive membrane that lays the back of the eye contains the sensory receptors for vision; these are rodes andcones, photoreceptors. More rodes (long, thin) than cones. Rods more sensitive to light than cones, so we rely on them at night, but cones are the one that distinguish color. Most cones are concentrated in the fovea.
The blind spot: the hole without any receptors, optic disk, because optic nerves leaves the eye. The blind spot is filled in our vision by the brain, using neighboring neurons withcolor and texture of surround visual information.
Processing visual information: is done primarily in the brain but it undergoes some preliminary processing in the retina by ganglion cell (some brain tissue migrates to retina during fetal development). Info from sensory receptors (cones and rods) is collected by bipolar cells and then channeled to ganglion cells (the bundled axons of these cellsform the optic nerve) but only from the receptors located in their “receptive field” . A ganglion cell receives info from one or two cones but from many rods, so cones are important for visual acuity (be able to see details)
The optic nerve leaves the eyes and they meet at the optic chiasm where they fibers split and crossover to the opposite side of the brain where they go to the thalamus...