Psych 169 Midterm 2

attention

selectively concentrating on some information while ignoring other information

“spotlight of attention”

attention lights up some parts of the world and leaves the rest in semidarkness

how is attention related to consciousness?

attention is the “**gatekeeper**”

1. is attention necessary for consciousness?
2. is attention sufficient for consciousness?

1. yes
2. no

attention can either be:

* involuntary grabbed
* intentionally directed
* different systems in the brain

involuntary control of attention:

* ventral attention system
* mainly in right hemisphere
* alerting system

temporoparietal junction

* involuntary control of attention
* integrates information from various sites: thalamus, visual, auditory

ventral frontal cortex

* involuntary control of attention
* involved in detection of unexpected targets

voluntary control of attention:

* **dorsal** attention **system**
* **bilateral**
* purposeful, high-level attention

intraparietal sulcus

* voluntary control of attention
* perceptual-motor coordination and directing eye movements

frontal eye field (FEF)

* voluntary control of attention
* responsible for saccadic voluntary eye movements

attentional blink

* you are less likely to detect a 2nd letter within 200 to 300 ms of the 1st target letter
* capacity to attend “blinked” for a moment
* similar to a neural refractory period

the half-second delay in consciousness

* experiments during the 1950s
* somatosensory cortex of awake subjects stimulated with electrode
* feels like being touched on the skin

low intensity electric pulses (the half-second delay in consciousness)

* no awareness of touch
* no matter how long pulse-train lasted

high intensity pulses (the half-second delay in consciousness)

* awareness only if pulse-train **> 0.5s**
* no awareness if pulse-train < 0.5s

“neuronal adequacy”

* Libet


* requires 0.5s stimulation in somatosensory cortex

how long does auditory stimuli take to get to brain?

10ms

how long does visual stimuli take to get to brain?

20 to 40 ms

does consciousness come much later? (Libet’s proposal)

* **subjective referral** of sensory experience **backward in time**
* strong stimulus to somatosensory cortex interferes with sensations coming rom touch
* **touch** the **skin** (wrist)
* you can **block** that **sensation** by stimulating the somatosensory cortex **up to 0.5s later**

Libet’s 2nd experiment

* brain stimulation first, touch stimulation second
* BUT, touch perceived first, brain stimulation perceived second

Libet’s idea on how sensations happen

1. information travels from skin to cortex
2. neural activity > 0.5s, stimulus is consciously perceived
3. your perception is **moved back in time** to match the actual time **when event happened**

sensory experiences are subjectively referred back in time

what point in time is the experience referred? (Libet)

* the experience is referred back to the primary evoked potential
* EP is a very fast neural signal following a stimulus to the skin (touching)
* no EP when stimulating cortex directly

summary of Libet’s theory of consciousness

1. need 500ms of neuronal activity
2. activity **

Libet’s view

consciousness **does really trail** half a second behind events of the real world, but **we don’t realize it**

fMRI

* functional magnetic resonance imaging
* measures blood flow to more active areas of the brain
* good spatial resolution (1 to 3 mm)
* poor temporal resolution (3 to 6 secs)

EEG (electroencephalography)

* brain waves measured from the surface of the scalp (non invasive)
* good temporal resolution
* poor spatial resolution

transcranial magnetic stimulation (TMS)

electromagnetic coil on the scalp creates magnetic field to induce an electrical current on a specific area of the brain

electrocorticography (ECoG)

* excellent temporal resolution
* excellent spatial resolution (depth electrodes)
* resolution: 0.3 mm (individual neuron)

neuroimaging methods

* fMRI
* EEG
* TMS
* ECoG

Freud (psychoanalysis)

id, ego, superego

Helmholtz

* **unconscious inference**
* involuntary **reflex-like mechanism** which is part of visual perception
* **visual illusions**: unable to consciously convince ourselves that our eyes are played tricks

visual illusions

unable to consciously convince ourselves that our eyes are played tricks

Muller-Lyer illusion model

sharp edges in **western architecture** may be the origin of illusion

* comparison with other cultures → the effect is still observed

examples of Muller-Lyer illusion

* dumbell illusion
* shepard tables illusion

subliminal (unconscious) perception

* widespread in 1950s
* James Vicary, marketing researcher, sales of popcorn and soda dramatically increased
* message **below threshold** of **conscious** awareness
* accessible to the unconscious mind
* no independent verification. later recanted.

semantic priming

* rapidly flash a word
* followed by masking stimulus
* subjects cannot report the word (below threshold of conscious perception)
* flash test words: (ex. chair, apple, child, etc.) and nonsense words (random letters)
* semantically related words are identified faster

evidence in science that subliminal (subthreshold) detection works

* semantic priming
* long way from **simple word recognition** to subliminal effects on **complex behaviors**
* research directly evaluating effects of subliminal messages on behavior regularly show **no effect at all** on behavior
* any change (improvement) results from other factors, ex. **expectancy effects**

2 distinct types of processing by the brain processing

1. fast, automatic, inflexible, effortless (**unconscious**)
2. slow, effortful, controlled, flexible, requires working memory (**conscious**)

causal efficacy

we often think our consciousness was responsible for that action

causal sequence seems to be…

1. consciously perceive
2. act on basis of conscious experience

long sequence of neural activity

* physical information transduced in sensory system
* nerve firings in visual system
* turned into conscious experience (where, how?)
* conscious experience acts back on brain
* causing more firing of neurons to direct action

role of consciousness in skilled movements

* serve crosses court in 0.5s at over 100 mph
* can hit ball with remarkable accuracy
* **conscious perception is not necessary for such skilled movements**

5 types of conscious and unconscious action

1. always unconscious
2. initially unconscious, but can be brought under conscious control
3. initially requires conscious effort (learning) but with practice become automatic
4. can be done either way (consciously or unconsciously)
5. always conscious

always unconscious

* you can **wiggle toes**
* can’t consciously control **spinal reflexes**
* these reflexes depend on neural circuits outside the brain and are always unconscious

some actions normally unconscious, but can be brought under conscious control

* **biofeedback**
* show you a monitor of your **heartbeat**
* you can learn to control it
* **breathing**

many skilled actions are initially learned with conscious effort, but become automatic

* **automation** (opposite of biofeedback)
* learning to ride a bicycle or any motor skill
* tennis serve, typing
* after complete automation, paying attention could be **counterproductive**

many skilled actions, once learned, can be done either way (consciously or unconsciously)

* driving a car
* sometimes you are aware of your driving
* other times you arrive at destination without apparently being conscious of the journey

some actions always seem to be done consciously

* trying to remember a name or directions
* when you make a difficult moral decision

what happens when subject is asked to point to a visual target?

* target is displaced during **saccade**
* subjects don’t notice displacement
* unconsciously adjust arm movement to the correct final position
* results suggest a **dissociation** between fast motor reactions and conscious perception
* 2 entirely different systems in the brain

dorsal or “where” stream

spatial processing

* location
* movement
* spatial transformations
* spatial relations

ventral or “what” stream

object processing

* color
* texture
* pictorial detail
* shape
* size

Milner and Goodale said the division should be…

* vision for action
* vision for perception

vision for action

fast visuomotor control

vision for perception

less urgent visual perception

what patient DF (visual agnosia) can do

* produce letters/numbers from memory


* recognize objects by touch
* reach out to objects and grasp them easily

what patient DF (visual agnosia) cannot do

* name simple line drawings
* recognize letters/numbers
* recognize shapes of objects by sight

patient DF

* visual agnosia from damage to occipital cortex
* cannot recognize objects by looking at them
* dissociation between motor performance and awareness
* could not do perceptual orientation matching
* but could do visuomotor “posting”

how could patient DF be unaware of the angle but post the card without problem?

* she has lost much of the **ventral stream** that leads to visual perception (Milner and Goodale)
* but retains **dorsal stream** needed for accurate visuomotor control

how could patient DF be unaware of the angle, but can accurately reach to take pencil?

* she has lost much of the **ventral stream** that leads to visual perception
* but retains **dorsal stream** needed for accurate motor control

visual agnosia

* results from damage to the “what pathway” (vision for perception)
* can be caused by lesions to the posterior temporal and occipital lobes

prosopagnosia

* face blindness
* results from damage to the fusiform face area

color agnosia

* fail to identify abnormally colored objects or pictures
* ventral occipital cortex
* knowledge of color-object relationships is defective

dorsal stream

fast skilled movement

ventral stream

object identification

2 cortical streams

* dorsal stream
* ventral stream

evolution of 2 cortical streams

fast/accurate response essential for catching prey, avoiding danger

Ramachandran’s idea about cortical streams

one of the streams is conscious and the other a “zombie”?

* dorsal stream: zombie (unconscious)
* ventral stream: not zombie (conscious)

Milner and Goodale’s idea about cortical streams

* “the visual information that the dorsal stream uses…remain quite inaccessible to consciousness…the ventral stream provides a conscious representation of the world”
* ventral stream is the “sole route to phenomenal visual consciousness”

blindsight

* usually damage to one side of **v1**
* shown a circle with stripes in blind hemifield
* subject: “I can’t see anything”
* experimenter: “just guess”
* correct over 90 to 95% of the time
* can have **afterimages**
* says can’t see color when looking at green stripes
* but closes eyes and says can see an afterimage (including stripes) that are complementary in color

blindsight and reading

* can’t read word on the “blind” side
* but a word in the blind field can influence (unconsciously) a **semantically related word** in the sighted field
* show “hand” to the blind side
* they will select “foot” (primed) instead of “apple” in the sighted field

blindseers have vision without consciousness

* can see “**functionally**” without the visual **qualia**
* can **track with their eyes** moving stimuli that they say they can’t see
* **grasp** objects they say they can’t see

Milner and Goodale’s idea about blindsight

it is a set of **visual capacities** mediated by the **dorsal stream**

blindsight depends on other structures

* **10 different parallel pathways** from eyes to brain
* 85% of cells take the major route (through v1)
* 15% go through the superior colliculus

blindsight and motion

* shown a moving object
* “I can’t see anything”
* but can accurately guess direction of motion
* the minor visual pathways have projections to **V5 (MT)** motion area

tactile vision substitution system (TVSS)

* back, abdomen, thigh, fingertips
* with sufficient training, blind subjects begin to perceive these tactile sensations as “**out there in space**”

sensory substitution

* tongue is far more sensitive than back
* 144 gold-plated electrodes
* within a few hours, a congenitally blind person able to move, grasp objects, catch a ball rolled toward her
* asked to see a flickering candle
* sound used to replace vision
* soundscapes
* pitch and time used to code left-right and up-down
* virtual reality spatialized sounds
* “see”depth and details of scenes

relevance of sensory substitution to consciousness

* subjects are **not consciously coding** the tactile information (pattern is **too complex**)
* it’s become automatic (**unconscious**) after a while
* picked up the **language** of a new sensory experience

anesthesia and unconscious processing

* induces unresponsiveness and amnesia
* but not necessarily unconsciousness
* **intraoperative awareness**

low dose of anesthetics

similar to drunkenness, amnesia, distorted time perception, and increased sleepiness

slightly higher dose of anesthetics

patient fails to move in response to a command and is considered unconscious

problem: unconscious or unresponsive?

clinical unresponsiveness is not necessarily synonymous with unconsciousness

isolated forearm technique (IFT)

* tourniquet is applied to the arm before anesthesia
* allows the hand to move while the rest of the body is paralyzed
* patients under general anesthesia can communicate using hand signals but postoperatively deny every being awake
* has shown that individual patients can be aware and responsive during surgery

consciousness vanishes when anesthetics…

produce **functional disconnection** across the brain, interrupting cortical **communication**

anesthetics cause unconsciousness when…

they block the brain’s ability to **integrate information**

anesthesia and the thalamus

most consistent effect produced by anesthesia is a **reduction of thalamic activity** suggesting that the thalamus may serve as a **consciousness switch**

GABA agonists injected into thalamus of rates caused…

they rapidly fall asleep

monkeys and anesthesia

* under stable anesthesia for 2 hours
* electrodes positioned in the thalamus
* stimulate the **thalamus**
* monkey instantly **wakes up**

2 main problems of free will

1. determinism


1. everything we do is predetermined
2. free will is an illusion
2. moral responsibility

determinism

universe runs by deterministic laws of physics

moral responsibility

if I am not truly free to choose my actions, then I should not be held morally (or legally) responsible

epistemic randomness

uncertainty due to lack of knowledge

ontological randomness

en event that is truly random by its very nature

* only known cases are in quantum physics

superposition

an element can be in two states at the same time

* will collapse into a single state when observed
* which state it ends in is truly random

brain activity during decisions

* **voluntary action** (volition) involves many brain areas
* converge on the **primary motor cortex**, which carries out motor commands

externally triggered (non-voluntary) actions

cerebellum and premotor cortex

voluntary (intentional) actions

1. supplementary motor area (SMA)
2. anterior cingulate cortex
3. Broca’s area

supplementary motor area (SMA)

involved in sequencing and programming motor acts

anterior cingulate cortex

involved in emotion, pain, and selection of information for action

Broca’s area

which produces motor output for speech

Phineas Gage

* damage to his left frontal lobe
* changed personality
* couldn’t behave responsibly