375: Attention Pt2

1. Change Blindness
1. This was an experiment where one person would give the participant a consent form to sign then duck to put the form in a cabinet and another person would pop back up
2. The idea was to find out if people notice when the person switches
1. 75% of the people did not notice
2. If the person happened to be attending to a specific detail that changed then they would notice
2. Does Attention Enhance Perception?
1. Experiment by Posner et al.
1. Participant had to click a button when the target appeared
2. There was a cue that would tell you what side of the screen the target would appear on
1. Half the time this cue was accurate and the other half it was misleading
3. When the cue was valid then reaction time would decrease (better performance)
4. If you have an invalid cue then the reaction time would increase (slower performance) than both situations of valid cue and no cue
5. Attention as a Spotlight
1. Attention is like the beam of a spotlight
2. Neural basis of the beam
1. 3 separate processes
1. Disengage, move, and engage
3. Problems with the beam metaphor
1. If you have to shift your attention greater distances it doesn't take more time than short shifts
2. Moving attention isn't slowed down by intervening stuff
1. Intervening objects should intervene and slow your attention down if beam metaphor is true but it doesn't
3. Attention selects space
1. He gave us the example of having red words and gray words written in the same space.  If sight was really a beam then we should be able to remember both words but since we were attending to the red most of the class didn't remember what the gray words were.
1. Implies that you are not switching to another location in space but instead to another object or object part
2. What if you are not attending to what you want to pay attention to?
1. Pop Out Effect
1. When the stimulus you are looking forward has a unique feature/single characteristic it sort of pops out at you
2. What if you have multiple characteristics in common?
1. Disjunctive Search
1. Definition
1. Single Characteristic defines your search
2. Process in Parallel 
1. All the stimuli is processed at once
2. Conjunctive Search
1. More than one Characteristic defines your search
2. Process is serial or you process things at different times till you find the stimuli
3. Parietal lobe damage
1. People with this type of brain damage cannot do a conjunctive search
2. Parietal lobe is necessary to perform this task
1. It lights up on fMRI when performing this task
3. Evaluate
1. Attention is selective, so you must always be evaluating other stimuli to see if they are more important than what you're attending to now.
2. Process
1. External stimuli TO processing physical characteristics TO process semantics TO awareness
1. Early filter theory
1. you only process the physical characteristics
2. Late filter theory
1. You process physical and semantics to find out if things are meaningful to you or not
2. Method to Study whether early filter theory or late filter theory is true
1. Early Filter Theory Evidence
1. Put different spoken words in different ears and said only attend to the right
1. Found that...
1. People don't remember words from unshadowed ear
2. People do notice if a tone is played or if there is a gap which is evidence for early filter theory
2. Late Filter Theory Evidence
1. Cocktail Party Effect 
1. Certain words will grab your attention even if you are at a party
2. Works about 1/3 of the time
3. Researchers proposed that all stimuli are evaluated for physical and semantic properties
1. However, it appears that the physical stimuli actually makes people switch attention so Early Filter Theory appears more correct (He went back on this in the next lecture and instead decided that it really depends on the situation.  Sometimes early filter is correct and sometimes late filter is correct.)
2. Really we don't know the exact process of focussing attention yet
4. Summary
1. Sometimes you must switch
2. Sometimes you must search
3. Always you must evaluate