unit 3 Flashcards
what are senation and perception, and what is meant by bottom-up and top-down processing?
sensation is the process by which our sensory receptors and nervous sytem receive and represent stimulus energies from our environment. perception is the porcess of organizing and interpreting this info, enabling recognition of meaningful events. sensation and perception are actually parts of one continuous process. bottom up processing is sensory analysis that begins at the entry level, with information flowing from the receptors to the brain. top down processing is info processing guided by high level mental processes, as when we construct perceptions by filtering info through our experiences and expectations.
how much information do we consciously attend to at once?
we selectively attend to, and process, a very limited portion of incoming information, blocking out much and often shifting the spotlight of our attention from one thing to another. focused intently on one task, we often display inattentional/change blindness to other events and changes around us.
what are absolute and difference thresholds, and do stimuli below the absolute threshold have any influence on us?
our absolute threshold for any stimulus is the minimum stimulation necessary for us to be consciouslly aware of it 50% of the time. signal detection theory predicts how and when we will detect a faint stimulus amid background noise. individual asbolute thresholds vary depending on the strength of the signal and also on our experience, expectations, motivation, and alertness. our difference threshold is the difference we can discern between two stimuli 50% of the time. weber’s law states that two stimuli must differ by a constant percentage to be perceived as different. priming shows that we can process some info from stimuli below our absolute threshold for conscious awareness. but the effect is to fleeting to enable people to exploit us with subliminal messages.
how do the eye and brain process visual information?
after porcessing by bipolar and ganglion cells in the eye’s retina, neural imoulses travel through the optic nerve to the thalamus, and on to the visual cortex. in the visual cortex, feature detectors respond to specific features of the visual stimulus. supercell clusters in other critical brain areas respond to more complex patterns. through parallel processing, the brain handles many aspects of vision (color, movement, form, and depth) simultaneously. other neural teams integrate the results, comparing them with stored info and enabling perceptions.
- light waves hit the cornea, which bends light to provide focus
- light enters through the pupil and the images are focused on the retina by the lens
- lights hits the retina, where there are rods, cones, and neurons that begin to process visual info
- each con transmits neural signals to one bipolar cell while rods send combined messages to bipolar cells
- the bipolar cells send signals to the optic nerve, where they travel through the thalamus to the visual cortex
- parallel processing occurs along with association areas
what theories help us understand color vision?
the young-helmholtz trichromatic (three-color) theory proposed that the retina contains three types of color receptors. contemporary research has found three types of cones, each most sensitive to the wavelengths of one of three primary colors of light (red/green/blue). hering’s opponent process theory proposed three additional color processes (red/green, black/white, blue/yellow). contemporary research has confirmed that, en route to the brain, neurons in the retina and the thalamus code the color-relted info from the cones into pairs of opponent colors. these two theories, and the research supporting them, show that color processing ocurs in two stages.
how did gestalt psychologists understand perceptual organization and how do figure-ground and grouping principles contribute to perception?
gestalt psychologists searched for rules by which the brain organizes fragments of sensory data into gestalts, or meaningful forms. in pointing out that the whole may exceed the sum of its parts, the noted that we filter sensory info and construct our perceptions. to recognize an object, we must first perceive it as distinct from its surroundings. we bring order and from to the stimuli by organizing them into meaningful groups, following such rules as proximity, continuity, and closure.
how do perceptual constancies help us organize our sensations into meaningful percpetions?
perceptual constancy enables us to perceive objects as stable despite the changing image they cast on our retinas, color constancy is our ability to perceive consistent color in objects even though lighting and wavelengths shift. brightness (or lightness) constancy is our ability to perceive an object as having constant lightness even when its illumination chnages. our brain constructs our experience of an object’s color or brightness through comparisons with other surrounding objects. shape constancy is our ability to perceive familiar objects (such as an opening door) as unchanging in shape. size constancy is perceiving objects as unchanging in shape despite their changing retinal images. knowing an object’s size gives us clues to its distance and vice versa but we sometimes misread monocular distance clues and reach the wrong conculsions.
what does research on restored vision, sensroy restriction, and perceptual adaption reveal about the effects of experience on perception?
experience guides our perceptual interpretations. people blind from birth who gain sight after surgery lack the experience to visually recognize shapes, form, and complete faces. sensory restriction research indicates that there is a critical period for some aspects of sensory and perceptual development. without early stimulation, the brain’s neural organization does not develop normally. peeopl given glassses that shift the world slightly to the left or right or even upside down experience perceptual adaptiation, they are initially disoriented, then they manage to adapt to their new context.
what are the characteristics of air pressure waves that we hear as sound and how does the ear transform sound energy into neural messages?
sound waves are bands of compressed and expanded air. our ears detect these changes in air pressure and transform them into neural impulses, which the brain decodes as sound. sound waves vary in amplitude, which we perceive as differing loudness, and in frequency, which we experience as differing pitch. the outer ear is the visible protion of the ear. the middle ear is the chamber between the cochlea and the eardrum. the inner ear consists of the cochlea, semicircular canals, and vestibular sacs. through a mechanical chain of events, sound waves traveling through the auditory canal cause tiny vibrations in the eardrum. the bones of the middle ear (hammer, anvil, stirrup) amplify the vibrations and relay them to he fluid-filled cochlea. rippling of the basilar membrane, caused by pressure changes in the cochlear fluid, causes movement of tiny hair cells, triggering neural impulses to be sent to the auditory cortex. sensorineural hearing loss results from damage to the cochlea’s hair cells or their associated nerves. conduction hearing loss results from damage to the mechanical system that transmits sound waves to the cochlea. cochlear implants can restore hearing for some people.
what theories help us understand pitch perception?
place theory explains how we hear high-pitched sounds and frequency theory explains how we hear low-pitched sounds. the volley principle explains how we hear pitches in the middle range. place theory proposes that our brain interprets a particular pitch by decoding the place where a sound wave stimulates the cochlea’s basilar membrane. frequency theory proposes that the brain deciphers the frequency of the neural impulses traveling up the auditory nerve to the brain.
how do we sense touch?
our sense of touch is actually serveral senses - pressure, cold, warm, and pain - that combine to create other sensations such as hot.
how can we best understand and control pain?
pain reflects bottom up sensations (such as input from nociceptors, the receptors that detect harmful temperatures, pressures, or chemicals) and top down processes (such as experience, attention, and culture). one theory of pain is that a ‘gate’ in the spinal cord either opens up to permit pain signals traveling up small nerve fibers to reach the brain or closes to prevent their passage. the biopsychosocial perspective views our perception of pain as the sum of biological, psychological, and socio-cultural influences. pain treatments often combine physical and psychological elements, including placebos and distraction.
how do we experience taste and smell?
taste and smell are chemical senses. taste is a combination of 5 basic sensations - sweet, sour, bitter, salty, and unami - and the aromas that interact with info from the taste receptor cells of the taste buds. there are no basic sensations for smell. we have about 20 million olfactory receptor cells with about 350 different receptor proteins. odor molecules trigger combinations of receptors, in patterns that the olfactory cortex interprets. the receptor cells send messages to the brain’s olfactory bulb, then to the temporal lobe, and to parts of the limbic system.
SMELL
- gas molecules of whatever you are smelling are sniffed into the nose. most molecules get trapped by the hairs lining the nose but some make it to the olfactory epithelium
- the olfactory epithelium contains ofalactory sensory neurons. the molecules are dissolved by muscus and then they bind to receptors on the olfactory sensory neurons.
- if the threshold is met, an action potential is fired up the axon (they converge at the glomerulus, where they are converted into brain signals and travel along mitral cells), through the ethmoid bone, and to the olfactory bone and the limbic system.
TASTE
- when you take a bite of food, the molecules enter the taste buds, which are sandwiched between fungiform papillae
- the taste buds contain 50-100 taste receptor epithelial cells which respond to different molecules in the food. each gustatory epithelial cell has a gustatory hair that goes to a taste pore
- food molecules dissolve in saliva then travel through taste pores so they can bind to receptors on gustatory cells and trigger an action potential that goes to one of four cranial nerves
how do we sense our body’s position and movement?
through kinesthesia, we sense the position and movement of our body parts. we monitor our body’s position and movement, along with maintaining balance, with the vestibular sense.
