PSYC 204 - Module 4

attention

the process by which certain is selected for further processing and other information is discarded

reasons why we pay attention

- the stimulus grabs our attention (bottom-up - REFLEXIVE attention)

- we are actively searching for it (top-down - VOLUNTARY attention)

reflexive attention

attention is involuntarily captured by external stimuli

voluntary attention

attention is voluntarily directed according to our goals and thoughts

selective attention

the process of picking out and maintaining focus on a particular quality, object, or event and ignoring other stimuli or characteristics of the stimuli due to specific goals, you tend not to notice other details irrelevant to your goal

change blindness

when your attention is guided by specific goals, you tend not to notice changes in the scene

orienting

moving the focus of attention

overt attention

when the focus off attention corresponds with eye fixation and with that is suggested by posture and head movements

voluntary (top-down) attention

attention driven by current goals & behaviors

reflexive (bottom-up) attention

attention driven by a stimulus

Posner's cueing task

voluntary orienting and involuntary orienting

voluntary orienting of attention

manipulated by a cue, which may be valid (correctly indicating the location of a target) or invalid (incorrect cue). Cueing is endogenous because the attention orientation is driven by the subjects' goal

involuntarily orienting of attention

when an external cue (e.g. a brief flash) draws attention to one of the two target locations

benefits and costs of orienting

B: gains in reaction time due to valid cues compared to neutral condition

C: slowing of reaction time due to invalid cues compared to neutral condition

covert attention

the focus of attention is not accompanied by eye or head movements

- we can enhance perception if we focus our attention on a location in the visual field

- however, enhancing perception in one part of the visual field takes place at the expense of other areas

cortical regions

frontal lobe, parietal lobe, frontoprarieal network

frontal lobe

ventral and superior prefrontal cortex (frontal eye fields) maintaining vigilance

parietal lobe

representation of spatial information, involved in top down attention control of spatial orientation

frontopparietal network

reorienting attention

subcortical regions

superior colliculus and pulvinar of thalamus

superior colliculus

involved in directing eye-movement

pulvinar thalamus

involved in attention control

pop out search

target defined by a single feature

conjunction search

conjunction of features that are also shared by distracters

Pop out search vs. conjunction search

pop-out search is fast and pre-attentive while conjunction search requires attention in a sequential manner (must attend to each individual object to detect targets)

feature integration model (Treisman and Gelade, 1980)

features of an object are integrated in a sequential manner; attention must be paid to one feature at a time; thus conjunction search is slow

Balint's syndrome

only one or a small subset of available objects is perceived at the same time, although patients can see each object when presented individually

- caused by bilateral damage to posterior parietal and occipital cortices

- problems with object based attention (rather than spatial attention as in the case of neglect)

hemispatial neglect

reduced attention to one (usually left) side of the scenes and objects, as though they do not exist. Affects the side contralateral to the side of damage

- typically caused by damage to the right parietal regions

- inaccurate determination of midline (line bisection test)

- applies to both external and internally generated (e.g. memory representations) objects and scenes

- patients are usually unaware of their abnormal condition

- a disorder of attention, not low-level perception

- still activates visual regions in occipital lobes that they claim not to be aware of

- they are often able to detect objects on the left if cued there (and can improve in the long run)

- affects auditory and tactile judgments, not only vision

divided attention

the ability to split attention between different sources of information or different tasks

stroop task

is one of the best known psychological experiments named after John Ridley Stroop. The Stroop phenomenon demonstrates that it is difficult to name the ink color of a color word if there is a mismatch between ink color and word. For example, the word GREEN printed in red ink.

Dorsal (fronto-parietal) attention network

- fontal and parietal areas

- concerned primarily with the control of spatial attention

- involved in voluntary attention to goal-directed locations and targets

Ventral attention network

- temporoparietal junction and ventral frontal cortex

- involved in stimulus-driven control (e.g. attending to unexpected stimuli) that is needed for disengaging and re-orienting attention to attend to novel stimuli

subcortical attention networks

attention is implemented in wide, distributed circuits (dorsal and ventral attention networks work together)

- attention is a dynamic system that flexibility allows for selection in many different ways

motor neurons

project from the ventral horn to muscle fibers

- alpha motor neurons and gamma motor neurons

alpha motor neurons

causing muscle contraction

gamma motor neurons

adjust the tension in the muscle for precision

spinal cord interneurons

coordination simple reflexes (e.g. knee jerk reflex)

descending motor pathways

- cortical/direct control

- subcortical/indirect control

cortical/direct control (Pyramidal/corticospinal CST track)

direct connection between the cortex and spinal cord

- originates mostly in the primary motor cortex, 80-90% crosses over in the medulla to regulate the contralateral side of the body

- regulates fine movement of parts

- damage leads to permanent loss of the fine control of the extremities

subcortical/indirect control (extrapyramidal tracts)

indirect control over spinal cord activity

- receiving inputs from cortical and subcortical structures

- regulate large and coordinated movements, such as posture, balance, muscle tone, startle and escape reflexes, etc.

cerebellum

does not initiate motor commands; coordinates movements by correcting unanticipated errors in ongoing motor processing in the motor and premotor cortices

- motor and non-motor functions

motor functions

- motor planning and execution

- posture and balance

- combines sensory and motor information to predict where and when an object will be

- damage leads to balance disorders

non-motor functions

- sends projections to the frontal lobe and influences cognition, emotion, motivation, and judgment

- impairment affects cognition, language perception, and grammar

basal ganglia

components include striatum (caudate and putamen), globus pallidus

- functionally connected to thalamus, substantial migration, and subthalamic nuclei

- action control, selection, & initiation of action

- every area of the cortex interacts with the basal ganglia via recursive loops circuits

- direct and indirect pathways

direct pathway

excitatory

indirect pathway

inhibitory

diseases of basal ganglia

Huntington's disease and Parkinson's disease

Huntington's disease

genetically based, usually expressed later in life; caused by neuronal death in the indirect pathway in the striatum

- symptoms: too much motion, which is often inappropriate; chorea

chorea

uncontrollable, jerky movements

Parkinson's disease

loss of dopaminergic fibers in substantia nigra

- symptoms: resting-tremors, rigidity in movements, shuffling gait, stooped posture, etc.

- treatment: stimulating dopamine receptors, or deep-brain stimulation

primary motor cortex (M1)

- voluntary movement

- somatotropic representation of the body

- origin of corticospinal pathway

- directly produce motor movements, or modulate spinal circuits to excite or inhibit more complex movements

- hemiplegia

hemiplegia

loss of voluntary movements on contralateral side of the extremities

premotor cortex (PMC)

- involved in externally guided action

- representations linked to the movement itself

- important for the preparation of actions

supplementary motor area (SMA)

- involved in internally guided action

- automatism

- akinetic mutism

automatism

behavior is automatically triggered by outside stimuli (lack of internal control)

akinetic mutism

no spontaneous behavior

prefrontal cortex

- involved in planning and higher aspects of control of action, such as selection of action, and maintenance of goals and responses

- setting and maintaining long-term goals

- damage to the PFC does not impair execution but actions become inappropriate or disorganized

the patient described in lecture D.F. had severe problems with object recognition. When presented with a circular block into which a slot had been cut:

D.F. was able to insert a card into the slot when asked to do so, even though she was unable to follow the instructions to orient the card so that it would fit

a main function of the Dorsal visual stream is to determine __________ objects are

where

in higher stages of visual processing, neurons have ___________ receptive fields

larger

anatomical outputs from the occipital lobe follow two major axon bundles that terminate in the _________ and __________

inferior temporal lobe; posterior parietal lobe

with regard to the two main output pathways from the occipital lobe, __________ is to ___________ as dorsal is to ventral

where; what

a patient who has difficulty matching pictures of the same object taken from different vantage points may be showing which dysfunction?

apperceptive agnosia

the patient in the video had a syndrome called integrative agnosia, which was characterized by difficulty in:

combining parts of objects into coherent whole percepts

the term associative agnosia is reserves for patients who:

cannot recognize objects despite having normal perceptual representations

patients with prosopagnosia typically have difficulty recognizing:

the faces of both their friends and famous people

_________ is to __________ as face recognition is to object recognition

prosopagnosia; agnosia

the statement "recognition of a visual pattern at a later time occurs only if you can match the stimulus to its exact stored representation" is most consistent with which theory of pattern perception

view-dependent

according to ________ theories of object recognition, when one sees an object such as a bicycle, recognition depends on the ability to detect properties that do not depend on specific viewing conditions

view-invariant

why do people fail to notice when the mouth and eyes of an inverted face remain upright?

the overall configuration remains the same

according to ensemble theories of object recognition, it is possible to confuse similar-looking objects because:

objects that appear similar activate overlapping networks of cells

a major source of evidence against the idea that faces are processed in the fusiform face area is that this region:

is also recruited when people have to make discriminations among highly familiar stimuli

the term _______ refers to the operations involved when we select for further processing a limited subset of information from the total information available to us from our sensory systems and stored mental representations

attention

failing to notice a change in your surroundings, such as someone removing an object, is called:

change blindness

during a particularly boring lecture, you carefully note the time on a clock that is mounted on the side wall of the classroom while keeping your eyes fixated on the professor's face. this is an example of:

covert attention

you are working diligently in the chemistry laboratory when suddenly a small explosion occurs in the rear of the room, immediately and automatically capturing your attention. this is an example of:

exogenous cuing

you are looking for a friend who is supposed to meet you in a crowded lecture hall. you know that she is wearing a bright purple sweater and glasses. which kind of visual search best describes this situation?

conjunction search

unilateral spatial neglect typically results from damage to the following region:

right hemisphere

neglect is a disorder of

attention

the main deficits in Balint's syndrome is that patients can focus on attention on only:

one object at a time

the ___________ attention network is goal-driven, and the ___________ attention network is stimulus-driven

dorsal; ventral

____________ is a higher-level skill that allows us to perform two or more tasks at the same time, and attention is required for the performance of all the tasks

divided attention

one major difference between the pyramidal and the extrapyramidal motor tracts is their points of origin. the pyramidal tracts carry messages from ___________________ to the spinal cord, whereas the extrapyramidal tracts carry messages from ____________________ to the spinal cord

cortical structures; subcortical structures

Parkinson's disease results from cell death in the ____________, which is a part of the ______________

substantia nigra; basal ganglia

two subcortical structures that play an important role in the preparation and execution of actions are:

cerebellum and basal ganglia

______________ seem(s) particularly important in the control and planning of complex motor sequences as opposed to simple movments

the motor cortex regions in the prefrontal lobes

the movements triggered automatically by outside stimuli, such as grabbing and drinking someone else's coffee, are called:

automatisms