PSYC Ch. 1

Sensation

Collection of information; conversion of stimuli into electrochemical signals in the body.

What muscles are responsible for altering the shape Of the lanes in accommodation

Cilliary muscles

Stereopsis

The perception of depth that arises from the integrated information received from both eyes, Such as retinal disparity and convergence

Light and shadow

Monocular depth cue. Patterns of light and shadow create the illusion of a 3-D object

Texture Ingredients

A monocular depth cue where closer object objects will have courser Texture/more Detail than distanced objects

Linear perspective

Monocular depth cue. The sense that parallel lines appeared to converge in the distance, Like railroad tracks

law of emergence

a gestalt principal that States that we perceive an object as a whole before recognizing its individual parts (Such as how different colored dots can be organized to make a cat on the background before you interpret individual dots)

Law of multi stability

Describe how human brain can perceive an ambiguous image in multiple, Distinct ways. Such as seeing a face or base in the same image, Or different orientations of a perceptual illusion cube

Law of subjective contours

Suggest that we Perceive edges of surfaces in locations where there is no physical contour in the image, Similar to law of closure, but for contours instead

Law of invariance

States that we perceive basic shapes is consistent and recognizable, Regardless of how they are Transformed, Rotated, Scaled, Or distorted

Perception

How the individual organizes and interprets the information; varies due to memory, emotions, and expectations.

Psychophysics

Quantifying the relationship between sensation and perception.

Top-down processing

when prior knowledge influences perception, using familiar contextual clues to fill gaps in the information (processing shortcut). Subject to bias and misinterpretation. Still need bottom up data to provide data for top-down processing to operate on

Bottom-up processing

perception is based on new stimuli from one’s current external environment (data-driving and not shaped by previous experiences). Still need top-down processing to interpret raw data from bottom up

Perceptual organization

Visual cues that help the brain make inferences when organizing visual information.

Binocular cues

Visual information from two eyes that provides depth perception, such as convergence and retinal disparity.

Retinal disparity

Disparity of the two images from each eye.

Convergence

The degree to which the eyes turn towards each other to focus on an object; greater convergence indicates a nearer object.

Parallax

subconscious comparison of the slightly different images from each eye

Monocular cues

Visual cues that require only one eye to provide depth perception.

Form

visual appearance of elements that the brain combines to create the perception of an object (important for monocular vision) (monocular)

Relative Size

makes a larger object appear to be closer when compared to smaller object at the same distance (a smaller ball in a image is thought to be further away) (monocular)

Relative Height

makes objects higher in our field of view appear to be more distant (bottom of the image is perceived to be closer to us while the top is more distant) (monocular)

Overlap/interposition

an object blocking out light from another object is perceived as closer (monocular)

Shading and Contour

perception of position and shape (monocular)

Motion Parallax

based on motion and reveals distance through relative motion. To a passenger in a moving car, the trees along the road will appear to pas by more quickly than the distant mountains (monocular)

Absolute threshold

The minimum intensity of a stimulus that can be detected 50% of the time.

Subliminal stimulus

A stimulus below the absolute threshold that may still have an unconscious effect.

Weber’s law

The noticeable difference for a stimulus is proportional to the intensity of the stimulus.

Signal detection theory

focuses on how an individual differentiates a signal (important stimuli) from noise (unimportant stimuli). Think of a deer differentiating the sound of an approaching tiger from random background forest noises. SDT differs from absolute threshold because SDT has a decision-making aspect of whether or not to ignore a stimulus

Sensory transduction

The process by which a physical stimulus is received and turned into an electrochemical signal.

Sensory receptors

Located in the peripheral nervous system to detect internal and external stimuli.

Tonic receptors

Receptors that respond slowly to stimuli and fire as long as the stimulus is present.

Phasic receptors

Receptors that adapt quickly to stimuli and fire only when the intensity of the stimulus changes.

Subjective constancy

we tend to perceive things the way we are accustomed to thinking about them (we assume that the sixe, color and shape of things remain constant)

Size constancy

perception that an object has a fixed size, regardless of the size of its image on the retina (think of how we perceive converging railroad tracks in a photo)

Color constancy

the perception that an object does not change color even though different lighting conditions can influence the wavelengths reflected by the object

Shape constancy

and object has a fixed shape regardless of the changing shape on the retina due to changing the angle the object is viewed from (think of how a door is perceived as rectangular even though it being open or closed is not a perfect rectangular image for our retina)

Gestalt principles

Grouping principles that suggest an image perceived as a whole has more information than its individual parts.

Figure-ground

the idea that humans organize their perceptions into figures and backgrounds

Law of Pragnanz

aka Law of simplicity. States that stimuli tend to be perceived as simple, orderly, and symmetric. Sometimes another name for Gestalt’s principles

Law of Proximity

objects close together are perceived as grouped

Law of Similarity

objects that have similar shape, color, or other qualities are perceived as grouped

Law of Closure

gaps between objects are perceived to be closed to form figures

Law of Continuity

aligned objects are perceived to continue behind obstructions

Law of Symmetry

objects are perceived in a way to make them symmetrical. The mind will connect two unconnected objects to make them one symmetrical piece (like two mirrored semi-circles)

Law of past experience

objects tend to be perceived based on past experiences

Law of Common Fate

objects that move together or change together  are perceived as grouped

Law of common region

objects in sharing a common region (such as inside of an outlined border) are perceived as grouped

Law of parallelism

objects that are aligned parallel to each other are perceived as grouped

Law of connectedness

connected objects are perceived as grouped

Just Noticeable Difference (JND)

the smallest noticeable change in the intensity of a stimulus while it is being experienced

Criterion

used in SDT to distinguish noise from a signal (identify what is actually important)

SDT

tendency to preferentially identify a sound as either a noise or a signal

SDT nonbiased criterion

produces same ratio of hits to misses and correction rejections to false alarms

SDT conservative criterion

aka strict criterion. Increase correct rejections but also decrease correct hits and false alarms. Increased specificity (likelihood of positive identification being correct)

SDT liberal criterion

decreases correct rejections and correct misses while increasing correct hits and false alarms. Increased sensitivity (negative indication is more lightly to be corrected, but positive identification is more likely to be incorrect)

SDT conservative strategy

preference for correct rejections over correct hits (a deer is brave and is more concerned about grazing than an approaching tiger). Prevails when individual is rewarded more for correct rejections

SDT liberal strategy

preference for correct hits over correct rejections (a frightened deer cares more about running from a tiger than grazing). Prevails when individual is rewarded more for correct hits

Sensory neurons

(aka afferent neurons) conveys information from sensory receptors to central nervous system

Free nerve ending receptors

dendrites embedded in the tissue

encapsulated ending receptors

dendrites encapsulated by connective tissue that enhances their sensitivity

receptor cells

distinct cells (not neurons) that go on to activate neurons

exteroreceptor

located near the external environment (like in the skin)

interoreceptor

located internally (such as sensing things from internal organs)

propioreceptor

located in a moving body part (typically to sense movement)

mechanoreceptor

respond to physical touch (like pressure, distortion, or vibration)

Pacinian corpuscles

respond to heavy touch (type of mechanoreceptor)

Meissner’s corpuscles

respond to light touch (type of mechanoreceptor)

Thermoreceptor

respond to changes in temperature, sometimes chemical stimuli

Nociceptor

respond to painful stimuli

Photoreceptors

detect physical stimulus of photons entering the eye

Chemoreceptors

respond to chemicals (usually for gustation and olfaction)

Transient receptor potential (TRP) channels

undergo conformational change when exposed to stimuli. The conformational change sets of chemical cascade that ultimately creates action potential. Important for thermoception and nociception

Aβ (A-beta) nerve fibers

fast conduction speed, thick diameter, thick myelination

Aઠ (A-delta) nerve fibers

medium conduction speed, medium diameter, light myelination

C nerve fibers

slow conduction speed, thin diameter, no myelination

How do receptors convey the intensity of a stimuli

they fire a greater number of signals/action potentials at a given time

Primary somatosensory cortex (PSC)

where somatosensory information ends up. Located in the postcentral gyrus of the parietal lobe

homunculus

representation of how different areas of the body take up different amounts of space in the PCS. Areas with more receptors (like hands or the lips) take up more space

Sensory adaptations

occur in response to short continuous exposure to stimuli. Adaptation of sensory systems’ sensitivity to their current environment (such as meissner’s corpuscles firing less rapidly to a constant pressure on the skin compared to when the pressure was first applied)

Cornea

Outermost layer of the eye; the first part that light hits when entering the eye.

Anterior chamber

Filled with aqueous humor; located after the cornea; provides nutrients and helps maintain eye pressure.

Lens

Changes shape to adjust focal length through a process called accommodation; located after the anterior chamber.

Accommodation for vision

Contraction of ciliary muscle to ensure the image is projected directly onto the retina.

Vitreous chamber

Helps focus light onto the retina; filled with vitreous humor; located after the lens.

Retina

Covers the back surface of the eye; contains photoreceptors like rods and cones; last stop for light entering the eye.

Rods

Photoreceptors that contain rhodopsin; detect all visible wavelengths of light; good for night vision.

Cones

Three types that detect slightly different wavelengths of light; important for distinguishing colors.

Fovea

Point on retina where vision is most acute; primarily made up of cones.

Iris

Colored portion of the eye that contains muscles to control the amount of light entering.

Pupil

The opening that lets light into the eye.

Choroid

Network of blood vessels that nourish the eye.

Sclera

The 'white' of the eye.

Phototransduction cascade

The process through which photoreceptors convert light into electrical signals.

On-center bipolar cells

Activate when light hits the center of the receptive field of photoreceptors.

Off-center bipolar cells

Become less active when light hits the center of the receptive field of photoreceptors.

Retinal ganglion cells

Receive input from bipolar cells; include on and off-center types.

Optic nerves

Axons from retinal ganglion cells that carry information from the eye to the brain.

Optic chiasm

Point where the axons from each eye cross to the opposite side of the brain.