Sensation and Perception (Cognition)

Not nearly as long, this is a fun unit. By the way, I forgor to mention that one side of the brain controls the other side of the body. Also, terms in this unit r a lot shorter than previous so yeah

Sensation

The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

Sensory receptors

Sensory nerve endings that respond to stimuli

Perception

The process by which our brain organises and interprets sensory information, enabling us to recognise objects and events as meaningful

Allows us to draw meaningful conclusions of the stimuli we are taking in from the external environment

Bottom-up processing

Information processing that begins with the sensory receptors and works up to the brain’s integration of sensory information

New ambiguous stimuli that builds to conclusion from the senses

Top-down processing

Information processing that begins with the sensory receptors and works up to the brain’s integration of sensory information

Expectation or assumption about what we are sensing is used to validate predictions

Transduction

The transforming of physical energy from sensations into neural impulses the brain can interpret

More formally it’s the conversion of one form of energy into another

Psychophysics

The study of relationships between physical characteristics of stimuli, such as their intensity, and our physical experiences of them

Absolute threshold

The minimum stimulus energy needed to detect a particular stimulus 50% of the time

Found by Gustav Fechner

Signal detection theory

A theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation;

Assumes there is no single absolute threshold

Detection depends partially on a person’s experience, expectations, motivation, and alertness

Subliminal

Below one’s absolute threshold for conscious awareness

Difference threshold

The minimum difference between 2 stimuli required for detection 50% of the time

We experience the difference threshold as a Just Noticeable Difference

Weber’s law

To be perceived as different, 2 stimuli must differ by a constant minimum PERCENTAGE instead of amount

Sensory adaptation

Diminished sensitivity as a consequence of constant stimulation

When constantly exposed to an unchanging stimuli, nerve cells fire less frequently and we become less aware of it

Wavelength

The distance from the peak of one light wave or sound wave to the peak of the next

Electromagnetic wavelengths vary from short gamma waves to the long pulses of radio transmission

Short wavelengths: blue
Long wavelengths: red

Hue

The dimension of colour that is determined by the wavelength of light; what we know as the colour names

Intensity

The amount of energy in a light or sound wave, which influences what we perceive as brightness or loudness

Determined by amplitude of wave (height)

Cornea

Eye’s clear, protective outer layer, covering the pupil and iris

Pupil

The adjustable opening in the centre of the eye through which light enters

It dilates or constricts with the help of the iris to allow light for the eye so further transformation can occur

Iris

A ring of muscular tissue that forms the coloured portion of the eye around the pupil and controls the size of the pupil opening

Lens

The transparent structure behind the pupil that changes shape to help focus images on the retina

Accommodation

The process by which the eye’s lens changes shape to focus images of near and far objects on the retina

Retina

The light-sensitive back inner surface of the eye, containing the receptor rods and cones, plus layers of neurons that begin the processing of visual information

Cones

Retinal receptors that are concentrated near the centre of the retina and function in daylight or well-lit conditions

Detect fine detail and give rise to colour sensations

Cone = Colour

Rods

Retinal receptors that detect black, white, and grey (shadows and depth), and are sensitive to movement. Rods aren’t necessary for peripheral vision and twilight vision, when cones don’t respond

Fovea

The central focal point in the retina, around which the eye’s cones cluster

Bipolar cells

Stimulated to begin firing neural impulses after rods and cones detect and activate ganglion cells

Ganglion cells

Cells where the axons form together the optic nerve

Optic nerve

The nerve that carries neural impulses from the eye to the brain

The first stop after the processing is the thalamus, which then directs the information onto the visual cortex within the occipital lobe of the cerebrum

Blind spot

The point at which the optic nerve leaves the eye, leaving a “blind” spot because no receptor cells are located here

Young-Helmholtz trichromatic (3 colour) theory

The theory that the retina contains 3 different types of colour receptors - one most sensitive to red, one to green, and one to blue

When they are stimulated they can produce the perception of any colour

Helped explain the global theory of colourblindness

Opponent-process theory

The theory that opposing retinal processes (Red to green, blue to yellow, white to black) enable colour vision

Neurons in the thalamus and visual cortex are turned on and off by the opposing processes which explains why we don’t see reddish-green mix, but a reddish-blue mix like magenta

When one pair gets tired, the other produces a hazy afterimage in the opposing colour

Feature detectors

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

Deconstruct and reassemble visual images

The eye receives disassembled bits of information that must be reassembled like a puzzle in order to process it

Fusiform face area

Helps recognise faces from various viewpoints after rearranging the angles, colours, size, and shape

Allows us to detect whether the faces are friend or foe

Parallel processing

Processing multiple aspects of a stimuli or problem simultaneously

Allows us to analyse multiple aspects of any sensory signals coming its way

Handles a variety of incoming messages and mostly happens unconsciously

Audition

The sense or act of hearing

Normal hearing has a wide range, with people’s voices being the best heard

Neural responses to sounds are transmitted much faster than vision

Frequency

The number of complete wavelengths that pass a point in a given time

Pitch

A tone’s experience highness or lowness

Depends on frequency, which is measured in hertz

Amplitude connects to loudness; the higher it is, the louder it is, and it’s measured in decibels

Middle ear

The chamber between the eardrum and the cochlea containing 3 tiny bones which concentrate the vibrations of the eardrum on the cochlea’s oval window

Hammer, anvil, and stirrup transmit vibrations onto the oval window

Cochlea

A coiled, bony, fluid-filled tube in the inner ear; sound waves travelling through the cochlear fluid trigger nerve impulses

Fluid in the cochlea move in response to vibrations and hair cells on the lower part of the cochlea on the basilar membrane bend

Hair cell movement triggers neural firing and the impulses travel down the auditory nerve into the auditory cortex in the temporal lobe

Loudness is determined by how many stimulated hair cells

Inner ear

The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

Sensorineural hearing loss

The most common form of hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve

Nerve deafness

Hair cells damaged

Caused by over-exposure to loud noises and damage from illness, but also genetics and aging play factor in this

Conduction hearing loss

A less common form of hearing loss by damage to the mechanical system that conducts sound waves to the cochlea

Cochlear implant

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

Place theory/coding

The theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated

Best describes how high pitches are sensed

Frequency/matching/temporal/volley theory/coding

The theory that the rate of nerve impulses travelling up the auditory nerve matches the frequency of a tone, thus enabling us to sense pitch

Sound locating happens with 2 ears

Touch

A tactile sense that people need from the beginning of life

Skin is the largest sense receptor and contains different cells for various touch sensations: pressure, warmth, cold, and pain

Other sensations are evoked by different combinations and intensity

Cognition can affect how we interpret the sensations of touch

Gate-control theory

The theory that the spinal cord contains a neurological gate that blocks pain signals or allows them to pass on to the brain

The gate is opened by activity of pain signals travelling up small nerve fibres and is closed by activity in larger fibres or by information coming from the brain

Nocireceptors(pain)

Biopsychosocial phenomenon

The receptors detect harmful temperatures, pressure, or chemicals

Pain is adaptive and helps us to know when something is wrong

Genetically, some people produce more endorphins that decrease pain responsiveness

Motivation and distraction can influence how much pain we feel

In memories, pain is often distorted or diminished

Affected by socio-cultural variables

Experience with pain can vary in social situations and be influenced by cultural norms through empathy or sympathy

Treatments include medicine, surgery, electrical stimulation, acupuncture, massage, exercise, and hypnosis

Placebos and distractions also help reduce pain

Phantom limb sensations

Pain sensations in amputees that occur in nonexistent limbs, show that biological signals aren’t needed for someone to experience pain

Gustation

Our sense of taste

Chemical sense that is also adaptive and helps us survive and thrive

5 basic tastes: sweet, salty, sour, bitter, and umami

Taste protects from bad food but also attracts us to pleasurable food

Psychological factors like expectations and framing can also influence how good something tastes to us

Taste buds

Cells located on tongue and in mouth to process the chemicals that allow us to taste

Receptors are sensitive but decrease in sensitivity aging

Olfaction

Our sense of smell

Oldest chemical sense and bypasses the thalamus directly to the olfactory bulb in the brain

Smell requires molecules to be processed by the receptor cells in nasal cavity. It helps us protect ourselves from damaging substances

20 million olfactory receptors that can detect a large amount of smells

Each smell triggers multiple neurons and is strongly connected to memory, as each smell can evoke a strong emotional memory of objects

Inability to smell is called Anosmia and is affected by age, gender, and experience

Kinesthesis

Our movement sense

Our system for sensing the position and movement of individual body parts

Simple tasks may require hundreds of muscles and sensors to send information to your brain and back out with commands

Vestibular sense

Our balance sense

Our sense of body movement and position that enables our sense of balance; works in conjunction to kinesthetic sense

Both also use receptors in the fluid filled semicircular canals and the calcium crystal filled vestibular sacs that both send information to the cerebellum to monitor sense of balance

Vision also plays a role in both

Proprioceptors

Position and motion sensors to send information to the brain and back out with commands

Senses chart

Sensory interaction

The principle that one sense can influence another as when the smell of food influences its taste

Embodied cognition

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

Selective attention

Focusing conscious awareness on a particular stimulus

Past experiences, emotions, attention, and expectations influence how we perceive the stimuli received by our sensory systems

Generally limited to one thing at a time, and is decided by importance

Focus shifts between tasks; no one can truly consciously multitask

Cocktail party effect

How we can perceive our own names amongst a cacophony of other sounds

Inattentional blindness

Failure to see visible objects when our attention is directed elsewhere

Change blindness

Failing to notice changes in the environment and is a form of inattentional blindness

Perceptual set

A mental predisposition or stereotype or expectation to perceive one thing and not another

Brain’s explanation of incoming sensations is influenced by experience, expectations, context, motivation, and emotion

Can influence what the senses think they sense

Perceptions can also be influenced by context, motivation, and emotion

Gestalt

An organised whole

Gestalt psychologists emphasised our tendency to integrate pieces of information into meaningful wholes

To create meaning, sensations must be organised and interpreted, and it all happens unconsciously

Figure-ground

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

Grouping

The tendency perceptually to organise stimuli into coherent groups

Default way we organise the world around us

Proximity

Nearby figures grouped together

Similarity

Similar figures grouped together

Closure

Brain fills in gaps to create a complete, whole object

Depth perception

The ability to see objects in 3D although the images that strike the retina are 2 dimensional, which allows us to judge distance

Develops over time and with the advent of independent movement

Visual cliff

A laboratory device for testing depth perception in infants and young animals

Monocular cues

A depth cue such as interposition or linear perspective available to either eye alone

Binocular cues

A depth cue, such as retinal disparity, that depends on the use of both eyes

Convergence

A cue to a nearby object’s distance, enabled by the inward angle of the eyes

Retinal disparity

A binocular cue for perceiving depth

Differences between what each eye sees, and the more there is, the closer the object is

Interposition

Use an object’s surrounding environment to determine how far away it is

Relativity

Use location, dimensions, and movement of an object to determine its distance

Shrinking objects are perceived as moving further away

Stroboscopic movement

An illusion of continuous movement as in motion picture experienced when viewing a rapid series of slightly varying still images

Phi phenomenon

An illusion of movement created when 2 or more adjacent lights blink on and off in succession

Autokinetic effect

The illusory movement of a still spot of light in a dark room

Affected by eye movement

Perceptual constancy

Perceiving objects as unchanging, having consistent properties even as illumination and retinal images change

Colour constancy

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

Perceptual adaptation

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

When sensations are restored, perception doesn’t always follow