Week 11 (Consciousness)

Consciousness

Paradoxically, although a tremendous amount of processing must be completed in order to create a conscious perception of the world, there is no "feeling" of the work involved

Split brain

severing the corpus callosum reduces severity of seizures but the brain can no longer communicate with other parts, and awareness of behaviour is altered because the right hemisphere cannot use language, it cannot understand the contents of the book and becomes bored looking at the pages. The left hand might wave (or make a rude finger gesture) without the knowledge or control of the individual.

Conscious content

• defined as the subjective experiences of your internal and external world

• sense of self

• plans

• dreams

• day to day perception of space and time

States of consciousness 

refers to different levels of arousal and attention

Attention

• the process of selecting information from the internal and external environments to prioritise for processing

• involuntary and automatic

Passive attention

occurs when bottom-up information from the external environment requires a response.

active attention

is when attention is directed by goals and top-down processing.

selective attention

occurs when you attend to one source of information while simultaneously ignoring other stimuli. occurs when you attend to one source of information while simultaneously ignoring other stimuli.

Selective attention example

For instance, we are more likely to attend to a bright light in a dim scene or a loud noise in a quiet room.

stimulus salience 

• refers to the bottom-up qualities of a scene that influence how we direct attention

• The colour of an object or the loudness of a sound are low level features that may direct your attention, at least initially

Attentional capture 

When attention is diverted because of the salience of a stimulus

top down processing

develop expertise in a given area, we are better able to allocate attention to the more important features of the scene and ignore information that is less relevant

automaticity

refers to fast and effortless processing that can be accomplished without conscious thought

Once a particular skill becomes automatic, it frees up attention to focus on other features of the environment

Cocktail party effect

Even when some information is not part of conscious awareness, this does not mean it is not being processed. (hearing your name while having a conversation at a cocktail party)

Dichotic listening task

• In this task, participants are asked to wear a pair of headphones that will play one message in one ear and a second, different, message in the other.

• Participants are asked to attend to and repeat one message and ignore the second. It should not surprise you to know that participants generally have very little trouble completing this task.

• Moreover, participants have a fair amount of difficulty reporting details of what occurred in the unattended ear.

Divided attention

or multitasking, is when we simultaneously attend to two (or more) tasks at the same time

Divided attention example

for instance, talking with a friend in the car about your class while driving. It should not surprise you to know that we are generally not particularly proficient at multi-tasking and often make errors.

Inattentional blindness

This occurs when we are engaged in one task and completely miss other information e.g. gorilla basketball

flicker task

Participants are shown two variations of the same picture, usually with one difference between the images.

Subliminal stimulus

a sensory stimulus that is processed, but does not reach the threshold for conscious perception.

Subconscious processing

information we are aware of, but not necessarily aware that it is influencing our behaviour.

Subvisual messages

messages that are presented too quickly for the visual system to perceive

Subaudible messages

are played at a low volume, typically with a louder message played over it

affect of subliminal and subconscious messages effect on behaviour

the general results are that these messages have minimal to no effect on behaviour.

Visual Neglect

disorder results from lesions on the right (inferior) parietal lobe of the cortex. Patients who are affected with damage to this region lose awareness of visual stimuli on the left

Stimuli in the neglected field can influence behaviour even if they are not consciously aware of it.

stages of sleep

• Awake

• Stage 1 sleep

• Stage 2 sleep

• Stage 3 sleep

• Stage 4 sleep

• REM sleep

Stage 1 sleep

• you begin to move from a state of relaxation to early sleep and the firing rate across the cortex becomes more synchronised.

• a very light stage of sleep; if startled or awoken, most people report that they were not even sleeping.

Stage 2 sleep

• The transition from stage 1 into stage 2 is best identified by the appearance of sleep spindles and K complexes.

• Although there is some theta activity, the waves are generally irregular. Sleep spindles are brief bursts of activity (12-14 Hz) that occur roughly 2-5 times a minute during stages 1-4 sleep.

  • currently thought that they play a role in memory consolidation

• K-complexes are easily identified on the EEG; they only occur during stage 2 sleep around once a minute. They can also be triggered by unexpected noises.

Slow wave sleep

stage 3 and 4

Stage 3 sleep

• the firing across the cortex becomes coordinated and we transition to delta activity. Delta is easily recognisable, consisting of slow (less than 4 Hz), regular, high-amplitude waves.

• ncludes around 20-50% delta activity

Stage 4 sleep

Stage 4 is typically referred to as the deepest stage of sleep. Only a strong stimulus will wake you, and you would feel groggy and confused upon waking.more than 50% delta activity

REM sleep

• several differences appear on the physiological measures we are collecting

• Desynchronised theta waves will start to appear on the EEG, and your eyes will start to move side-to-side beneath your closed eyelids. The brain becomes highly active; in fact, the EEG looks more similar to when you are awake and alert than the slow predictable waves from a few minutes earlier

• body might twitch but other than that very still

• can easily be woken up by hearing something meaningful like your name

• blood flow is in the brain is generally reduced, but the visual association cortex and the prefrontal cortex do receive a large proportion of oxygenated blood being the basis for vivid visual images and hallucinations we experience while we sleep

• It is hypothesized that this is the reason that signals from the brain to the body are dampened. This inhibition keeps us from acting out our dreams.

functions of slow wave sleep

• more important for restoring the brain than the rest of the body

• after one night without sleep, most participants demonstrate few physical effects.

• . People deprived of sleep can be irritable, disoriented, and have more difficulty completing cognitive tasks.

• After a few days of deprivation, it is not uncommon for people to report symptoms that include mild hallucinations

• the metabolic rate and blood flow of the cortex decline substantially relative to wakefulness

• We have also observed that regions that have the highest activity during waking hours also show the greatest reduction in metabolic activity and the most delta activity during SWS, suggesting that this part of the brain is resting.

Functions of REM

• The eyes move rapidly from side-to-side, your heart rate will suddenly quicken or slow, breathing becomes less regular and brain activity changes across the surface of the cortex

• This rebound phenomenon suggests that there is a need for a certain amount of REM. Researchers have also noted that there is an increase in the percentage of time spent in REM during periods of intense brain development

• infants spend more time in REM than anyone else

• important in consolidating long term memories

• The people who did not sleep during the day did worse on the task that evening. The performance of people who only entered SWS remained about the same as earlier in the day, but the group that achieved REM actually improved on the task

dreams

• Unfortunately, there are a number of problems with examining dreams through self-report

• individuals do not always remember their dreams, and when they do, they cannot always accurately describe them.

• nightmares often occur during SWS and were you to wake a person during this slow wave sleep, they are often able to report that they were dreaming, but the memories are more fleeting. The vivid narrative-based dreams that participants often report tend to occur during REM

biological clocks

• Sleep and wakefulness vary throughout the day, but so do other physiological activities, like body temperature, blood pressure, hormonal secretions, and pain tolerance.

• We are a diurnal species that evolved under predictable conditions of light and dark.

Circadian rhythms 

circa means “about” and dies means “day,” and these cycles are indeed a little longer than 24 hours in duration

Sleep disorders

Dissomnias, not being able to sleep

Parasomnias disorders during sleep