Test 1 Flashcards
Abrams, Chasten, Pratt
Saccades: measured in young adults and elderly adults- found no change in speed suggesting the important function of saccades
Saccadic suppression
Visual processing is suppressed during a saccade
Shepard & Metzler
3D Shape Rotation: is mental visualization also suppressed? Showed people two shapes and asked if one could be rotated to match the second
Findings: longer preparation time = shorter time to rotate
Irwin & Carlson-Radvansky (1996)
Does eye movement pause mental rotation?
Same task as previous study (two objects- is it a rotation of the other?) but this time objects are located at a distance from each other (either short or long distance)
Findings: while the farther distance offered more time for mental rotation, the saccade required pauses rotational processing
Overt attention
An obvious shift in attention done with eye movement
Covert attention
Shift of attention that is entirely internal (in the mind)
Stimulus Onset Asynchrony (SOA)
The time between the cue and target appearing in a visual cueing task
Time is needed to react to a cue for it to effect visual attention; if SOA is shorter than reaction time it is not useful
Cueing paradigm: endogenous versus exogenous
To study endogenous shifts (conscious), researchers use a cue in the fixation point
To study exogenous attention (externally directed), researchers use a cue on target box (draws attention peripherally)
Inhibition of Return (IOR)
The overcompensation of inhibitory functions on exogenous cues (peripheral) causes slower reactions to previously attended cueing locations
Posner
Spotlight Theory: the idea that visual attention is like a spotlight; strongest in the centre and weaker as it reaches the edges ; attention sweeps like a spotlight
Information in the centre is clearest to process, but we still take in information of lower quality from periphery
Flanker paradigm
Similar to Posner’s studies but uses letter targets to attempt activation of the linguistic systems
Object attention
Focusing on a particular object rather than a region of space
There is an object to be attended to despite alternative sensory input
Duncan (1984)
Can we selectively attend to one of two objects, even when they share the same location in space?
- Showed two objects, each with two features (orientation, dashed/dotted, size)
- If object attention is an ability, you should be able to report characteristics better for two objects contained in one (compared to two seperate objects)
Finding: hypothesis was correct, same-object (with different features) had quicker responses than different objects
Egly, Rafal, Driver, & Starrveveld (1994)
- Posner’s spatial queing paradigm but with stretched target boxes, meaning tagets can appear at different locations within one box
- An 80% predictive cue appears in a target location (this means endogenous attention is being measured, pre-decision);
- if attention is cued to the left box, object attention chooses the left box (if the target appears in that box it is quickly attended to)
- When cue was in correct box (object) but wrong location, spatial attention is used
- If the cue is in the wrong location and wrong object (box), object-attention is used
FINDINGS: both spatial and object attention are active; when attending an object, the WHOLE object is attended to - When driving, you narrow spatial attention to the road; when a car appears, object attention is activated
Occlusion
The process whereby something is hidden or obscured from prominence or view
- Your brain can fill in objects that are incomplete/blocked
- Object attention spreads past occluders
Pop-Outs/Singletons
A visual search in which all distractors are homogenous, with the target having unique characteristics
- Always quick to find
Conjunction Search
A visual search in which the target can only be identified by its conjunction of features (red & circle)
- The more distractors, the more scanning = longer to find
- This creates the “search slope”
Anne Treisman (1970s)
Feature Integration Theory (FIT):
Explanation for why pop-out searches are faster
1) Paralell Pre-Attentive Stage: spatial attention scans all locations and activates “feature maps” of each feature (colour, form, size, etc.)
- Pop-outs are found in this stage because a single map is able to identify the target
- In a conjunction search, we need object-attention
2) Serial Attentive Stage:
- Object attention
- Combines feature maps to bind features into a single object
- Serial Spotlight: we do this with each object in serial order while sweeping
Jeremy Wolfe (1990s)
Guided Search:
Improvement of Treisman’s model
1) Bottom-up processes: basic features are assigned activation values (#) based on their differences to neighbours; high activation value gains attention
- Feature maps are integrated into “activation maps” based on uniqueness; if the value exceeds the threshhold, it will “pop-out”
- When multiple features are combined, this process isnt efficient, so we use:
2) top-down processes: task demands alter activation values; the information we give our visual system about the features of our target give those features more value/more attention
- We use serial search to search through these items for features that match our information in order from highest value to lowest
Why is Guided Search considered better than the FIT model?
- The guided search model offers an explanation for why triple conjuntion searches (target containing 3 features) are quick when according to FIT they would be slow
- It is because 3 features offer MORE INFORMATION to our top-town processes, allowing us to locate the target quicker than if we only knew 2 features
Visual Working Memory
AKA visual short-term memory
- The memory system for storing visual information that one is currently attending to; fairly stable over time but limited
Luck & Vogel (1997)
Change Detection Task:
- Wanted to know how many coloured squares could be held in the VWM
Experiment 1) participants shown 1, 2, 3, 4, 8, or 12 coloured squares (100ms), followed by a blank screen (900ms/1sec), then asked which squares changed
FINDING: correct responding decreased significantly at 4 squares and beyond
- But how do we know this isnt verbal memory (repeating the colours in one’s head aloud)? –> had participants repeat a number in their heads (using verbal memory) while completing the same task
Experiment 2) participants must remember colour and orientation (did the colour OR orientation change?)
- In a set of 4 lines, 8 features were needed to be assessed (4 colors & 4 orientations)
FINDING: participants could still remember 3-4 items
Experiment 3) Did colour, orientation or gap presence of the line change?
FINDING: participants could accurately remember close to 16 features, but only because they are associated with at most 4 objects (the features are chunked/bundled together into single objects)
