Week 3 Flashcards
What are the two ways eye movements can provide insights?
Characteristics of the eye movements themselves
- Schitzophrenia
- Adhd
The location of eye movements
- Autism
- Eating disorders
What are attentional biases ?
Certain groups display different visual behaviours about where they look, how long they look for,
Whats are Saccades?
Overt, ballistic eye movements aimed at bringing a target into foveal vision
Vehicle to get fixations in the right place
Purpose: to get the eye to the next spot for clear vision
what are internally and externally guided Saccades?
External – participants are instructed to look at a visual stimulus as soon as it appears
- - Or visual stimuli attracts attention
Internal – saccades are executed in the absence of visual stimulus
- Nothing special is happening in a spot, but you look there
- Top down knowledge to get your eyes to a spot
If someone performs poorly on a Smooth Pursuit Eye Movement task, what would you expect to see?
If someone performs poorly there might be…
Compensatory saccades – catch-up to the target
There is some difficulty matching gaze verlocity to target verlocity
Falling off track, then making a sacade to get back on track
anticipatory saccades
saccades that deviate from a target and then back
This might reflect a disruption of pursuit by the saccadic system because of a failure of inhibition
An inability to inhibit the sacadic system
What are Pursuit eye movments?
For tracking objects that move relatively slowly and smoothly, we use something referred to as smooth pursuit eye movements (Fukushima, 2003)
How do normal healthy controls & those with Schizophrenia differ in pursuit eye movements?
Normal
- - Eye tracking is smooth when following stimulus
Schizophrenia
- Jerky motion, jagged
- Not able to follow the stimulus smoothly
What are Compensatory saccades?
used to catch-up to a target
There is some difficulty matching gaze verlocity to target verlocity
Falling off track, then making a sacade to get back on track
What are anticipatory saccades?
anticipatory saccades are when you allocate your eye gaze to an area where information is about to be
This might reflect a disruption of pursuit by the saccadic system because of a failure of inhibition
An inability to inhibit the sacadic system
What are the two fazes of smooth pursuit?
The initiation phase
Get it on track to be able to find where the target is
Maintenance phase
Staying on track with the target and matching the velocity
Problems can arise at both or one of these phases
You might be able to find the target ok, but not able to track, or vise versa
What did Ross et al find?
Ross et al., 1999 looked at eye movements in a number of groups
results; non-psychotic children of schizophrenic patients displayed similar intrusive saccades as those with adult-onset schizophrenia.
Conclusions; Eye tracking could possibly provide a marker for the likelihood a child might develop schizophrenia
What did Karatekin and Asarnow (1999) find?
aim: do typically developing children and children with schizophrenia look in different places when asked to do the same task?
Method: Asked typically developing (TD) children, and children with schizophrenia to view pictures with different questions in mind
Global questions (e.g., what is happening in this picture?) Require integration of all information
Focal questions (How old do you think each person is?) Require information from 2-3 places
Counting question (e.g., Count the number of cups on the table)
Results: Examined the percentage of regions fixated in each question
They found that there were no elevated looks to task-irrelevant locations in any task, in schizophrenia (and ADHD) compared to TD.
So while saccadic behaviours (particularly in SPEM) are affected, this does not seem to affect scene viewing
Conclusion - these intrusions (seen in the smooth persuit task) do not seem to translate in scene viewing when particpants have a question in mind
Participants perform the same, and are able to ignore irrelivant information
What did Munoz et al., find?
Hypothesized that children and adults diagnosed with ADHD may have specific difficulties in oculomotor tasks (moving eye tasks) requiring the suppression of reflexive or unwanted saccadic eye movements. To test this:
Participants: adhd patients and controls
Task: There were two conditions…
In the pro-saccade task, participants were instructed to look from a central fixation point (FP) towards an eccentric visual target (T).
In the anti-saccade task, stimulus presentation was identical, but participants were instructed to suppress the saccade to the stimulus and instead look for the central fixation point to the side opposite the target.
When the target appears, fixate on a point opposite to the target (inhibit the response)
Results: The results suggest that ADHD participants have reduced ability to suppress unwanted saccades and control their fixation behavior voluntarily, a finding that is consistent with a fronto-striatal pathophysiology (where we expect this work to be occuring in the brain).
What is Williams syndrome?
Drive toward social behaviour, often labeled as “hyper-sociability” or “pro-social compulsion”
They demonstrate:
Desire to interact with people (regardless of familiarity)
Hold prolonged face gaze during interactions
What is Autism (ASD)?
Characterised by
Social withdrawal
Lack desire to engage in social interactions
Opposite to williams syndrome
What did Riby & Hancock’s (2009) study look at?
The Embedded face task
Procedure:
5 second presentation
‘look at scene for as long as it remains on screen’ There was a head in the picture
Paricipants
typically developing people
Williams syndrome
Autism
Results
Individuals with Williams Syndrome fixated upon the embedded faces for longer than participants who were developing typically
- Did not focus on other details of the picture
Once the face had been detected, participants with autism spent significantly less time fixating on it than individuals without autism
When viewing this scene, the autism group shows the same anti-social trends (Lack desire to engage in social interactions)
Is vision passive or active?
early researchers believed that vision was bottom up and driven by salients (we look at things that the brightest and stand out)
other researchers believe that vision is more top down (we look where we need to extract information from)
However, it is both
What is ‘Cognitive Ethology’?
rather than being locked into a laboratory paradigm with the a priori assumption that the paradigm or task that is being applied is tapping into processes that are expressed in everyday life-situations, one would instead opt to explore first how people behave as they function within a naturally occurring situation. Once this complex problem space is identified and described then one could begin to move into the laboratory to test hypotheses that are generated by real-world observations. We have called this approach ‘Cognitive Ethology’.
