Classically, attention has been associated with a network of cortical sites that often include areas like the right parietal lobe, the frontal eye fields, and the superior temporal gyrus. Subcortical sites mentioned include the pulvinar - the thalmus’s big mystery - and the superior colliculi. And up to a few decades, the cerebellum was dismissively relegated to motor function. However, the cerebellum has been making a come back for a while now with an ever enlarging recognition of its role in cognitive functions, perhaps most successfully in learning. Under the leadership of Chris Striemer of MacEwan University and the able support of his student Brandon Craig, we at Waterloo have had the chance to participate in a study examining the effect of cerebellar lesions on attentional functioning. This work is still on going, but preliminary findings were presented by Chris at the annual meeting of the Cognitive Neuroscience Society in San Francisco this month (March 2017). The principal result so far has been an association of lateral cerebellar damage with changes in inhibition of return. Look for more findings in this space next year. For more details, feel free to contact Chris. A link to the poster is here.
Probability effects tend to resemble ones obtained with traditional 'attentional' manipulations. Cued or probable objects are detected faster and more accurately. This goes beyond simple detection tasks. Even in perceptual estimation tasks, both spatial exogenous cuing Anderson & Druker (2013) and orientation probability (Anderson, 2014; Jabar & Anderson, 2015) improve precision.
However, are they both the same effect? Do they share the same mechanisms? We investigated this in a paper we recently submitted. By having both manipulations in one block, we could look at whether the effects interact or not.
Blue = High-Prob, Red = Low-Prob
While both orienation probability and spatial exogenous cuing led to changes in initiation time, the effects were very clearly additive. What about precision?
Still no interaction. While both orienation probability and exogenous cuing led to changes in angular precision, the effects were very clearly additive again (panel b). Curiously, while both manipulations affected angular precision, only orienation probability did this by changing the shape of the angular error distribution (panel a), as characterized by a kurtosis metric (panel c). This kurtosis finding matches what we reported in our previous papers (Anderson, 2014; Jabar & Anderson, 2015).
These results only seem to make sense if the effects work through different mechanisms. While both these effects seem 'attentional', surely it only leads to confusion to put them both under the same umbrella? Such studies highlight the importance of examining how seemingly similar effects might just differ when studied more closely.
The paper has been provisionally accepted at Frontiers in Psychology. Will update with a link once the paper is published online. Feel free to contact us if there are any queries. Update: Click here for the paper
Our group will be presenting a couple of posters at this year’s Society for Neuroscience conference. Do swing by the posters if you get the chance!
One poster we will be presenting is on our work with orientation probability. We have constantly found that probable tilts are represented more precisely than improbable ones. Our hypothesis has been that exposure to such probablistic infomation tunes the relevant perceptual processing neurons, which in this case, would be the orientation-selective V1 neurons. Consistent with the hypothesis, we demonstrate that orienation probability robustly modulates ‘C1’, an early (90-100ms peak) ERP component which has been source-localized to the calcarine cortex. This activity correlates to the decisional ‘P3’ component, without modulating the ‘attentional’ ‘P1’ and ‘N1’ components. Thus, orientation probability effects likely are not the result of ‘top-down’ attentional mechanisms, but rather, reflect localised changes in early perception.
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