Local Bias and Updating

Recently Isabella Sewell tackled the details of getting a study on line. This month the fruits of that effort were shared as a poster at the Neuroxchange 2021 undergraduate neuroscience on-line conference. Isabella was doing her undergraduate thesis with co-supervision by James Danckert and myself. James and I are interested in how we revise our models of the world in light of new information. We call this mental model updating, and we know that brain damage in either hemisphere can impair this skill. We have wondered if the two hemispheres might play different roles in this process. One classical division between the roles of the left and right hemispheres is for local and global processing. Isabella took this idea and developed a tool that we might use to probe hemispheric specializations. In her experiment a triangle points either up or down and the participant's task is to predict the direction of the next triangle to be shown. For this task there is a global influence: a long time frame, repeating pattern of up-pointing more likely, alternating with down-pointing more likely. There is also a local bias in which the probability of the direction of the triangle is more likely to repeat. Experimentally you can mix these two biases in whatever proportion you propose. For this first assessment Isabella mixed these two distributions: the repetition probability and the global bias, in equal proportions. She found that participants were influenced by these biases, but in this cohort at least (healthy undergraduates) the local bias was all that we needed to predict partipants' choices. Of course, we have only begun to explore some of the variations possible with this procedure. If you have ideas please feel free to share them with us (or Isabella). And if you want to know what comes next "watch this space."