How can we help?

You can also find more resources in our Help Center.

AP Psychology - Chapter 4

Sensation & Perception
STUDY
PLAY
Sensation
the process by which a stimulated receptor creates a pattern of neural messages that represent the stimulus in the brain
Perception
a mental process that elaborates and assigns meaning to the incoming sensory patterns
Core Concept of Sensation & Perception
The brain senses the world indirectly because sense organs convert stimulation into neural messages.
Transduction
the transformation of 1 form of energy to another - especially by the transformation of stimulus info into nerve signals
Sensory Adaption
loss of responsiveness in receptor cells after stimulation has remained unchanged for a period of time
Absolute Threshold
the amount of stimulation necessary for a stimulus to be detected
Difference Threshold
the smallest amount by which a stimulus can be changed
JND
just noticeable difference; same as difference threshold
Weber's Law
states that the size of a JND is proportional to the intensity of the stimulus
Fechner's Law
expresses the relationship between the actual magnitude of the stimulus and the its perceived magnitude
Steven's Power Law
the relationship between the magnitude of a physical stimulus and its perceived intensity or strength; more accurate than the other 2 laws
Signal Detection Theory
provides an accurate portrayal of sensation; occurs outside of consciousness; explains how we detect signals & states that sensation depends on stimulus characteristics, background stimulation & the detector
Subliminal persuasion
the brain perceives information below the level of the conscious mind using a variety of techniques (subliminal advertising)
Core Concept of Senses
Senses all operate in the same way but each extracts different info and sends it to its own specialized processing region in the brain.
Retina
thin, light-sensitive layer at the back of the eyeball which contains millions of photoreceptors & other nerve cells (where transduction occurs for sight)
Photoreceptors
light-sensitive cells (which include rods & cones) in the retina that convert light energy to neural impulses; the farthest place light reaches in the visual system
Rods
photoreceptors in the retina that are very sensitive to dim light but not to colors; allows you to function in near-darkness & cannot make distinctions to sense color
Cones
photoreceptors in the retina that are very sensitive to colors but not to dim light; each is specialized to detect the light waves we sense as blue, red, or green
Fovea
center of the retina that give us our most sharpened vision; we use this to scan any visual interest
Optic Nerve
transports visual information from the eye to the brain
Blind Spot
part of the retina that has no photoreceptors and is located at the point where the optic nerve exists each eye
Role of the Visual Cortex
transforms incoming neural impulses into visual sensations of color, form, boundary, & movement; transforms 2D patterns to 3D
Brightness
these sensations come from the intensity or amplitude of light & is determined by how much light reaches the retina; sensed by the level of neural activity produced in the retina & passed along optic paths
Physical Properties of Color
it is a psychological sensation, not a property of things in the external world; called a hue
Psychological Properties of Color
color exists only in the mind of the viewer & is a sensation that the brain creates based on the wavelength of light striking our eyes
Electromagnetic Spectrum
the entire range of electromagnetic energy, including radio waves, X-rays, microwaves, & visible light
Visible Spectrum
pure energy of a tiny part of the EMS to which our eyes are sensitive
Trichromatic Theory
3 receptor explanation for color vision & sensation; colors are sensed by 3 different types of cones sensitive to light in red blue & green wavelengths
Opponent-process Theory
the idea that bipolar cells in the visual system process colors in complementary pairs (red/green, blue/yellow); better explains some cases of color blindness
Color Blindness
typically a genetic disorder that prevents an individual from discriminating certain colors
Frequency
pitch; the number of vibrations or cycles completed by a wave in a given amount of time usually in a second
2 Physical Properties of a Sound Wave
frequency & amplitude
Amplitude
loudness/intensity; a measure of the physical strength of the sound wave
Tympanic Membrane
eardrum; receives vibrating waves of air & transmits them to 3 tiny bones which pass them on to the cochlea, the primary organ of hearing
Cochlea
where sound waves are converted into nerve messages
Basilar Membrane
a thin strip of tissue sensitive to vibrations in the cochlea; converts the vibrations into neural messages by hair cells (receives sound)
Role of the Auditory Cortex
processes neural messages to make experiences we know as music, whispers, shouts, doorbells, etc
3 Sensory Qualities of Sound
pitch, timbre, loudness
Pitch
a sound wave's frequency determines the highness or lowness of a sound
Loudness
determined by a sounds physical strength or amplitude
Timbre
the quality of a sound wave
Conduction Deafness
the ways in which sound waves are converted to nerve energy have been interfered with or interrupted; result of very loud sound or trauma
Nerve Deafness
linked with a deficit in the body's ability to transmit impulses from the cochlea to the brain; damage that has occurred to the auditory nerve; most people born death have this type
How are visual & auditory sensations alike?
Both sensations are processed by neural messages sent to the region of the cortex; different regions of the brain, when activated, produce different sensations
Vestibular Sense
the body position sense that orients us with respect to gravity & tells us how our bodies - especially our heads - are postured, whether straight, leaning, reclining, or upside down; also tells us when we are moving or how our motion is changing
Kinesthetic Sense
the body position sense that keeps track of body parts relative to each other; makes you aware of crossing your legs, for example & tells you which hand is closer to a ringing phone
Olfaction
sense of smell
Olfactory Bulb
where sensations of smell are realized
Pheromones
chemical signals released by organisms to communicate w/ other organisms of their species; often used by animals for sexual attractions, danger, food sources, etc
What 2 senses are based on chemistry?
smell & taste
Gustation & its 5 Qualities
sense of taste - sweet, sour, bitter, salty, umami (MSG)
Papillae
taste receptors
Where are taste sensations sent?
somatosensory cortex
Source of brain processing for touch
skin senses that are connected to the somatosensory cortex, located in the parietal lobes
Where is the greatest skin sensitivity?
where we need it the most - face, tongue, & hands
Experience of Pain
can arise from intense stimulation of various kinds, such as a very loud sound or heavy pressure; sensations of pain arise in the brain itself & not the damaged nerves in the sensory pathways
Gate-Control Theory
assertion that pain depends on relative amount of traffic in 2 different sensory pathways; an explanation for pain control that proposes we have a neural "gate" that can block incoming pain signals under some circumstances
Purpose of Pain
serves as an essential defense signal, warns us of potential harm & helps us survive in hostile environments
Placebo Effect
a response to a placebo (fake drug), caused by a subject's belief that they are taking real drugs
Pain Threshold
varies enormously from person to person
Relationship between Perception & Sensation?
Perception brings meaning to a sensation, so perception produces an interpretation of the world, not a perfect representation of it
Percept
what we perceive; the meaningful product of perception - often an image that has been associated with concepts, memories of events, emotions, and motives
Feature Detectors
cells that detect certain stimulus features such as length, slant, color and boundary
Binding Problem
the unknown knowledge of how the brain manages to combine (or bind) the multiple features it detects into a single percept (ex: a face)
Bottom-Up Processing
stimulus-driven processing; perceptual analysis that emphasizes characteristics of the stimulus, rather than our concepts and expectations; thorough but time consuming
Top-Down Processing
conceptually-driven processing; invokes a perceiver's goals, past experiences, knowledge, expectations, memory, motivations, or cultural back round; quicker & inferential
Perceptual Constancy
ability to recognize the same object as "constant" under the different conditions such as changes in illumination, distance, or location
Illusion
what occurs when your mind deceives you by interpreting a stimulus pattern in a manner that is demonstrably incorrect
Ambiguous Figures
stimulus patterns that can be interpreted in 2 or more ways; no right way
Gestalt Psychology
"whole"; emphasizes how we organize incoming stimulation into meaningful perceptual patterns; Gestalt psychologists believe that much of perception is shaped by innate factors built into the brain
Figure
a pattern that grabs our attention
Ground
backdrop against which we perceive the figure
Closure
allows us to see incomplete figures as wholes by supplying missing segments, filling gaps, and making inferences