Unit 4- AP Psych

Sensation & perception

Sensation

Sensation

• Our senses (sight, sound, taste, touch, smell) have picked up info from the environment and that info is sent to the brain

• Bottoms up processing

Bottoms-up processing

starts at sensory receptors and works up to the brain’s higher levels of processing

Perception

• Our brain organizes and interprets in information sent to it by our senses

• Top-down Processing

Top-down Processing

Information processing guided by higher level mental processes drawing on our experiences and expectiations

Selective Attention

• What our conscious awareness is focused on

• Ability to tune in some stimuli and tune out others

Inattentional Blindness

1. Unaware of visible objects when our attention is focused elsewhere

2. Magicians use this

Change Blindness

Failing to notice changes in the environment

Transduction

Conversion of one form of energy into another. In sensation, transforming of stimulus energies into neural impulses our brain can interpret

3 basic steps to all our sensory systems

1. We receive sensory stimulation through receptor cells

2. We transform that stimulation into neural impulses

3. Those neural impulses are delivered to the brain

Converting one from of energy into an other that your brain can interpret

Psychophysics

Studies relationships between the physical characteristics of stimuli and our physical experience of them, like intensity

Gustav Fechner

German Scientist and Philosopher who studied the edge of our awareness of faint stimuli (absolute threshold)

Absolute Threshold

Minimum amount of stimulation necessary to detect by our senses 50% of the time (aware)

Subliminal

Stimulus you cant detect 50% of the time = its below our absolute threshold (unaware)

Signal Detection Theory

1. How and when we detect the presence of a faint stimulus amid background stimulation (hearing your name said in a loud room)

2. Assumes there is no single absolute threshold based partly on a person’s experience, expectations, motivation, and alertness

3. Assumes there is no single absolute threshold depends partly on a persons

Difference Threshold

1. Minimum difference between 2 stimuli or a present stimuli a person can detect half of the time

   • music volume

   • Mom’s voice among other women’s

2. Weber’s Law- to be perceived as different, 2 stimuli must differ by a constant minimum % not amount

Sensory Adaptation

Diminished sensitivity to constant or routine odors, sights, sounds, and temperatures

• senses adjust

Our sensory system is alert to novelty, but with repetition it frees up our attention to more important things

Perceptual Set

A mental predisposition (set of assumptions and tendencies) to perceive one thing and not another

• affects top-down

• Influences how we interpret stimuli

Context effect

The influence of surrounding information on perception or memory recall. It shows that context can impact how we interpret and remember things.

• cultural context helps inform perceptions

Top down processing shaping our perception of different things, a lot of what we perceive has bias

Motivation

Motivations can bias our interpretations of neutral stimuli

• desirable objects seem closer than they really are

• Hills look bigger and farther when we are tiered or carrying something heavy

Emotion

Emotions can influence perceptions

• hearing sad music can make people interpret words with diff meanings as the sad versions

• When angry people may perceive nearby objects as guns

• When mildly upset people percieve neutral faces as less attractive/ likeable

Extrasensory Perception (ESP)

The controversial claim that perception can occur apart from sensory input (telepathy, clairvoyance, precognition)

Telepathy

Mind 2 mind communication

Clairvoyance

Perceiving remote events (2nd sight)

Precognition

Perceiving future events

Parapsychology

Study of the paranormal (ESP or psychkinesis)

What do skeptics argue about ESP

1. To believe in ESP you must believe the brain is capable of perceiving without sensory input

2. Researchers have been unable to replicate ESP phenomena under controlled conditions

Light Energy

• Our eyes recieve light energy and transduce it to neural messages

• 2 physical characteristics of light

  1. Wavelength

  2. Intensity- brightness

Wavelength

Distance from one wave peak to the next = helps to determine hue (actual color)

Intensity

Wavelengths amplitude, amount of energy the wave contains - influences brightness

Cornea

1. Light enters here first

2. Protects eye and bends sight

3. Provides focus

Pupil

• adjustable opening in the center of the iris

• Determines how much light enters the eye

• Size varies to accommodate light, also if we are feeling amorous, it dilates

Iris

Colorful muscle tissue surrounding the pupil (controls the pupil)

Lens

• behind the pupil

• Changes shape and curvature to produce clearest projected image to the retina → accommodation → upside down image sent to retina

Retina

Light sensitive inner eye containing receptor cells (cones and rods) and neurons that begin to process visual info

Rods

Detect black/ white and light vision (necessary for peripheral vision)

Cones

Detect hue and color vision. Clustered more densely in the fovea (point of central focus) there are more cones than rods

Optic nerve

• located in the back of the eye and it takes info gathered by rods/cones and sends messages to brain

• The location where the optic nerve leaves the eye = there are no receptor cells (rods/cones)

Visual information processing

• Eye → Optic Nerve → Thalamus → Visual Cortex in the occipital lobe

• Feature detection- nerve cells in the brain respond to specific features (shape, angle, movement, lines)

• Allows us to recognize who/ what we’re looking at

Young-Helmholtz Trichromatic (3 colors) Theory

• 3 different color sensitive cones (red, blue, green)

• Most common form of color-blindness (inability to see the difference between red and green - sex linked)

Herring’s Opponent (Opposite) - process theory

• neurons involved in color vision are stimulated by one color’s wavelength and inhibited by another’s

• Opposing retinal processes (red-green), (yellow-blue) enable color vision

Blind Spot

The point at which the optic nerve leaves the eye, creating a “blind” spot bc no receptor cells are located there

Fovea

Central focal point in the retina around which the eye’s cones cluster

David Hubel and Torsten Wiesel

Showed that our visual processing deconstructs visual images and reassembles them

Feature Detectors

Nerve cells in the brain’s visual cortex that respond to specific features of the stimulus (shape, angle, movement)

Primining

the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response

Parallel processing

Processing many aspects of a problem at the same time

• the brain’s natural mode of information processing for many functions, including visions

Figure ground

The organization of the visual field into objects that stand out from their surroundings

Gestalt Psychology

1. Means to “form” or “whole”

2. The brain has a tendency to integrate pieces into meaningful wholes (necker cube)

3. Figure-Ground

4. Grouping

Grouping

Perceptual tendency to organize stimuli into coherent groups

• proximity

• Continuity

• Closure

Proximity

Group nearby figures together

Continuity

We perceive continuous patterns

Closure

We fill in gaps to create a complete object

Depth Perception

1. Retina sees 2D our brain organizes into 3D

2. Visual Cliff experiment with toddlers

Binocular Cues

We use 2 eyes to judge distance and depth by retinal disparity : our eyes are about 2.5 inches apart, meaning that the retina receives slightly different images

The greater the difference between 2 images= the closer the object

Monocular Cues

Depth cues available to either eye alone

Interposition

When an object partially blocks our view of another object its closer

Relative size

2 similar objects = smaller one is far awy

Linear perspective

Parallel lines look like they are getting closer at a distance

Relative height

Things that are closer appear bigger

Relative size

Comparison of the size of objects or figures in relation to one another, allowing us to determine which is larger or smaller.

Relative clarity/texture gradient

Closer things appear more clear

Phi-Phenomenon

Illusion of movement created when 2 or more adjacent lights blink on and off in fast sucession

Interposition

When an object partially blocks our view of another object

• means the object we can see more of is closer

Accomodation

The process by which the lens of the eye changes shape to focus on objects at different distances, allowing clear vision.

Bipolar cell

A type of neuron found in the retina that plays a crucial role in transmitting visual information from photoreceptor cells to ganglion cells. Bipolar cells receive input from photoreceptor cells and then transmit signals to ganglion cells, which send information to the brain. They are responsible for integrating and processing visual signals before they are sent to the brain for further interpretation.

Ganglion cells

Specialized neurons in the retina that transmit visual information from the photoreceptor cells to the brain. They have distinct receptive fields and are responsible for processing and transmitting visual signals such as color, contrast, and movement.

Perceptual Constancy

perceiving objects as unchanging even as illumination and retinal images change

Top down processing

Color Constancy

Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

Figure ground relationships

The visual perception principle that distinguishes objects from their background based on contrast, shape, and size. It helps us perceive objects as separate from their surroundings.

Perceptual adaptation

The ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field

sound waves

Compression and rarefaction of air molecules

sound waves are converted into neural impulses in hair cells of the inner ear

Frequency

The number of complete wavelengths that pass a point in a given time (ex: per second)

Pitch

A tone’s experienced high or lowness; depends on frequency

Audition

The act or sense of hearing

The process of hearing

Sound waves hit the eardrum, inducing vibrations that pass through the three bones of the middle ear (hammer, anvil, and stirrup) to reach the cochlea, a fluid-filled tube within the inner ear. The membrane-covered opening of the cochlea vibrates, generating ripples in the basilar membrane and causing the bending of hair cells. This motion activates impulses in neighboring nerve cells, which converge to create the auditory nerve. The resulting neural messages travel to the and subsequently to the auditory cortex in the temporal lobe.

Short version of the process of hearing-

(Vibrating air - tiny moving bones - fluid waves - electrical impulses to the brain)

(Sound waves - auditory canal - eardrum - tiny bones (hammer, anvil, and stirrup) - cochlea - basilar membrane - hair cells - nerve fibers - auditory nerve - thalamus - auditory cortex in temporal lobe)

Sensorineural hearing Loss

Hearing loss caused by damage to the cochleas receptor cells or to the auditory nerves; the most common form of hearing loss - nerve deafness

Conduction hearing loss

1. Outside of ear

2. Defects in external ear parts cause hearing loss, problem with outer or middle ear, blocking the canal

3. Makes soft noises difficult to hear because sounds can’t get through the outer or middle ear

Place Theory

We hear different pitches because different sound waves trigger activity in different places along the cochleas basilar membrane by vibrations. Thus, the brain determining pitch by generating a neural signal

Frequency Theory

The brain reads pitch by monitoring frequency of neural impulses traveling up the auditory nerve. The whole basilar membrane vibrates w/ incoming sound waves, triggering neural impulses to the brain at the same rate as the sound wave. - The rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone; enabling us to sense its pitch. Best explains how we sense low pitches. 

Locating Sound

Bc of the placement of our 2 ears we have stereophonic (3D) hearing. Bc sound travels 761 mph and human ears are 6in apart, the intensity difference and time lag are small but a noticeable difference in the direction of the 2 sounds corresponds to a time difference. Our super sensitive auditory system helps us detect these really small differences to locate sound.

Cochlear implant

A device for converting sounds into electrical signals and stimulating the auditory nerve thru electrodes threaded into the cochlea

Touch

Essential to our psychological/ emotional development

• distinct skin senses- pressure warmth, cold and hot (cutaneous), balance and body coordination (kinesthetic)

Pain

The body’s way of telling us something is wrong = changes our behavior

1. Women are more pain sensitive (can also endure more pain)

2. Both bottom-up (senses to the brain) and top-down (past experiences) are involved

3. Biological influences (nociceptors) sensory receptors detecting hurtful temps, pressures, or chemicals

Gate Control Theory

The spinal cord contains a neurological “gate” allowing some pain messages to have a higher priority than others

Psychological influences on pain

1. The intensity of pain at the end of an event is most likely to influence our memory of a painful event

2. You can control pain by distracting the brain

Taste (other name)

Gustation

Gustation diff tastes

Sweet, sour, bitter, salty, and umami

Taste

• chemical sense- taste buds catch food chemicals

• Taste buds replace themselves

• As we grow older taste buds decrease= lowers taste sensitivity (alcohol and smoking)

• Flavor of food is a combo of taste and smell

Smell - other name

Olfactory

Olfactory

• Chemical sense

• Learned association with humans (forming memories)

• Part of the limbic system = triggers memory and emotion

Sensory interaction

The principle that one sense may influence another, as when the smell of food influences taste

Embodied cognition

The influence of bodily sensations, gestures, and other states on cognitive preferences and judgements

Vestibular sense

Our sense of body movement and position that enables our sense of balance

• physical warmth can promote social warmth

• Social exclusion can literally feel cold

• Judgements of others my mimic body sensations

Kinesthesia

Body position- any change in position of a body part interacting with visoion

Convergence

With both eyes we know something is closer because our eyes look closer together and as we look at something farther away our eyes straighten out