Selective Attention Flashcards
How is attention divided between voices?
- the ‘cocktail party’ problem
- can’t understand/remember the contents of 2 concurrent spoken messages, the best we can do is alternate between attending selectively to the speakers
- bottleneck somewhere in the process (process of perception of speech sounds, lexical access, finally syntactic parsing and semantic interpretation)
How is attention focused on 1 of 2 simultaneous speech messages?
- shadowing (repeating aloud) one of the messages is successful if the messages differ in physical properties (location/voice/amplitude), isn’t successful if they differ only in semantics
- words repeated 35 times in unattended message aren’t remembered better than word heard once
How does attentional selection precede lexical identification and access to meaning?
- unattended words are filtered out early, after analysis of physical attributes and before access to identity/meaning
- we’re aware of unattended speech due to it having a pitch/loudness and phonetic characteristics, we don’t process identity/meaning
- if required to extract identity/meaning from 2 sources participant has to switch attention filter between them which is a slow and effortful process
What is the filter model?
Broadbent, 1958
- sensory features of all speech sources are processed in parallel and stored briefly in sensory memory (echoic memory)
- selective filter is directed only to one source at one time
- filter is early in processing so only information passes through it achieves recognition, activation of meaning, representation in memory, control of voluntary action and access to conscious awareness
- proven not to be all-or-none: partial breakthrough of meaning of unattended words, e.g. own name often noticed in unattended speech (Moray, 1959)
What are the ‘late selection’ theories that were inspired by breakthrough demonstrations?
- both attended and unattended words processed up to and including identification and meaning activation
- relevant meanings then picked out on basis of permanent salience/current relevance
- doesn’t explain why selection on basis of sensory attributes is more efficient than selection on basis of meaning and why GSR to unattended probe words is weaker than attended words
What is the filter-attenuation theory?
Treisman, 1969
- early filter that isn’t all-or-none (it’s an optional strategy)
- attenuates input from unattended sources with top-down activation
- unattended words if salient/contextually relevant can still activate meanings
What is the attentional spotlight of covert attention?
Posner et al, 1978/1980
- endogenous cueing: probable stimulus location indicated by arrow cue or not (neutral cue)
- participant responds as fast as possible to stimulus (maintaining central fixation)
- simple RT to onset, choice ‘spatial’ RT, choice ‘symbolic’ RT
- all faster for expected location and slower for unexpected
How are endogenous and exogenous shifts different?
- endogenous: voluntary, top-down
- exogenous: stimulus-driven, bottom up
- RT faster after sudden onset/change at the stimulus location although it doesn’t predict the stimulus location
- timing of exogenous cueing is different from endogenous
- exogenous attraction of spotlight is fast (<200 msec)
- endogenous movement of spotlight takes several hundred msec
How does voluntary attention to a spatial locus modulate early components of the ERP in extra-striate visual cortex?
- Mangun et al (1993)
- stimulus produces more activation when the subject attends to the side where the stimulus is being presented
What is the early selection in primary visual cortex and even LGN?
- with fixation maintained on central point, series of digits appears at fixation and high/low contrast checkerboards appear in left and right periphery
- p either counts digits at fixation/detects random luminance changes in left/right checkerboard
- fMRI BOLD signal is greater with attention directed to that side than with attention to fixation
- there’s some selection that occurs very early in processing
- visual selection is not all-for-one but is an optional process
What is inattentional blindness?
- experiments require participant to attend closely to one coherent ‘stream’ of visual events on the screen, spatially overlapping with another stream
- highly salient events in the unattended stream are missed by a large proportion of the participants
- the events of the unattended stream don’t appear to be processed to the level of meaning
What is cognitive capacity and how does it relate to multi-tasking?
- there’s limits to cognitive capacity: all processes take time, there’s limits to input that 1 process can handle, representational/storage capacity is limited
- capacity limits become more obvious when resources must be shared between tasks
- when we try to do tasks simultaneously there’s competition for shared resources
- when we try to switch between tasks the overhead includes: set-shifting/task-switching costs, retrospective memory, prospective memory
How is dual task interference measured in the lab?
- 2 tasks, designed for measurement and manipulation
- need to measure performance on both tasks as they may be able to trade off between tasks
What are the possible sources of dual-task interference?
-slower and less accurate performance in dual task conditions might be attributable to: competition for use of specialised domain-specific resources, competition for use of general-purpose processing capacity, limited capacity of executive control mechanisms that set up and manage flow of information through system and/or sub-optimal control strategies
What is the competition for domain-specific resources?
- 2 continuous speech inputs cannot simultaneously be understood or repeated
- performing a spatial tracking task interferes with use of visual imagery to remember stuff
- Kahneman (1975) proposed pool of general-purpose resource or effort shared among concurrent tasks, capacity may vary over people and within people, over states of alertness and level of ‘sustained attention’. if the sum of capacity doesn’t exceed total available there’d be no interference
