Lecture 17 - Selective Attention Flashcards
What is attention?
The mental process of selectively focusing on specific information while ignoring others
–> We cannot attend to everything so we attend to some things and not others
Where does attention fit in the Memory Storage Model?
Between SENSORY MEMORY and Short-Term Memory
If we attend:
Sensory Memory –> STM
If we don’t attend then the information is lost
Outline The ‘Cocktail Party’ Problem
We cannot understand/remember the contents of two concurrent spoken messages
–> The best we can do is alternate between attending selectively to the speakers
What is “shadowing”, when is it successful? When is it not successful?
Shadowing - repeating aloud a message
Successful if the messages:
–> differ in physical properties (location, voice, amplitude)
Not successful if they differ only in
–> semantic content (eg. novel versus a recipe)
What type of changes do/don’t participants most commonly notice in an unattended message?
PHYSICAL changes
- location, voice, volume, gross phonetics (eg. English to Czech)
NOT SEMANTIC CHANGES
(eg. meaningful to meaningless)
Does attentional selection precede lexical identification and access to meaning?
It seems that unattended words are “filtered out” early, after analysis of physical attributes, before access to identity/meaning
So: though aware of unattended speech as sounds with pitch, loudness etc. –> we do NOT seem to process their meaning
If we are required to extract identity or meaning from two sources, P has to switch the attention filter between them (slow and effortful process)
Outline Broadbent’s “Filter Model”
Inputs
o attended message
o unattended message
—> both to the SENSORY STORE
–> both to the selective filter
HERE there is a BOTTLENECK
–> only the ATTENDED message goes through to higher level processing
–> this attended message then to working memory
______________________________________________________
Sensory features of all speech sources are processed in parallel and stored briefly in sensory memory (echoic memory)
A selective “filter” is directed only to one source at a time
Filter is EARLY in processing - so that only information that passes through filter achieves recognition, access to conscious awareness, representation in WM, meaning activation etc.
Broadbent’s Theory ALSO ASSUMES
- Filter is all-or-none
- Filter is obligatory “structural bottleneck”
Is filtering all or none? What are the challenges to Broadbent’s filter theory?
BUT: theory is challenged
There are examples of partial “breakthrough” of meaning of unattended speech in shadowing experiments
–> Own name often noticed in unattended speech (but things like digits not) (Moray 1959)
Lackner and Garrett (1972)
- Attended: They saw the port for the first time
- Unattended: They drank until the bottle was empty
o GSR evoked by “Chicago” in unattended message, although it’s not remembered
–> Effect GENERALISES to related city NAMES
- MEANING HAD BEEN ACTIVATED (not just sound pattern detected)
Outline the “Late Selection” theories of auditory attention (breakthrough theory)
Theory: Both attended and unattended words processed up to and including IDENTIFICATION AND MEANING ACTIVATION
–> Relevant meaning then picked out on basis of permanent salience or current relevance (the filtering is AFTER)
but doesn’t explain: selection on the basis of sensory attributes more efficient than meaning selection, GSR to unattended probe words weaker than to attended
Resolution of theory contradictions: What is Filter-Attenuation Theory
There is AN EARLY FILTER (like Broadbent suggested) but it is NOT ALL-OR-NONE
–> It attenuates (turns down) input from unattended sources
–> Early filtering is an optional strategy NOT a fixed structural bottleneck
Inputs
o Attended message and unattended message
–> both to sensory store, both to ATTENUATING (turns down unattended inputs based on physical properties)
THERE IS THEN A BOTTLENECK
–> Both to higher level processing and both to working memory (but the attended message MORE)
Monitoring for Targets in auditory selection: Ostry, Moray and Marks (1976)
Monitoring for target word (animal)
Left Ear: plate cloth day fog tent risk bear
Right Ear: hat king pig groan loaf cope lint
TASK: press L or R key when animal heard
FOUND: After practice - target detection as accurate when word target must be detected on either ear, as only on ear
Visual Attention: Is it easy to visually attend?
- What is the ‘attentional spotlight’ Posner et al. (1978)
Easy to attend - can focus gaze
BUT…
Processing of information in the visual field to the level of recognition and meaning is HIGHLY SELECTIVE and LIMITED
–> The ‘spotlight’ of visual attention can be moved voluntarily (and relatively slowly) to locations/objects of potential interest away from fixation
–> It is attracted AUTOMATICALLY AND FAST to local transients in the visual field
–> The size of the spotlight can be varied and zoomed
This selective filtering occurs EARLY in the processing of visual information (eg. brain activation measures)
Processing of objects outside the “spotlight” is relatively shallow (little evidence for object recognition), or activation of meaning (eg. inattentional blindness” and visual search tasks)
How does reaction time change in endogenous (voluntary, top-down) vs exogenous (stimulus driven, bottom up) shifts in visual attention
RT faster just after sudden onset/change at the stimulus location
ALTHOUGH it does not predict the stimulus location
–> Timing of this exogenous cueing is different from endogenous:
- Exogenous attraction of the “spotlight” is fast (<200msec)
- Endogenous movement of “spotlight” takes several hundred msec
Are there neural correlates of visual attention (evidence from ERPs)
ERPs
If a stimulus appears in the ATTENDED location - we get big amplitudes of wave form
vs
A smaller amplitude waveform in unattended area
Outline the role of early selection in Primary Visual Cortex and LGN
Retina –> lateral geniculate nucleus –> V1
Experimental Method:
While fixation is maintained on central point
o series of digits appears at fixation and high or low contrast checkerboards appear in left and right periphery
fMRI BOLD signal in LGN/V1 voxels that react to checkerboard luminance change is GREATER with attention directed to that side with attention to fixtion
–> SO: at least some selection for regions in the visual field occurs VERY EARLY IN PROCESSING
