The cognitive brown bag this week on Wednesday April 10 at 12:00 in Tobin 521B will be given by Sandarsh Pandey (https://www.umass.edu/pbs/people/sandarsh-pandey). Title and abstract are below. All are welcome.
Investigating the properties of hierarchical ensemble representations
An ensemble representation contains the global summary statistic (mean, variance, etc) of a group of individual representations. Individual ensemble representations of different features (orientation, size, facial expression) have been extensively studied but not a lot is known about how multiple ensemble representations interact with one another. In our study, we generate a hierarchical stimulus by spatially arranging small circles of varying sizes to form several bigger circles of varying sizes. Participants either estimate the mean size of the smaller circles (lower level ensemble representation) or the mean size of the bigger circles (higher level ensemble representation). We were interested in answering two questions – whether the two representations are independent of one another and whether there was a cost involved in holding both representations simultaneously (compared to just holding a single lower or higher level representation). Results indicated that the lower level ensemble representation biased the estimation of the higher level ensemble representation, though the reverse was not true. We also found that despite ensemble encoding being fast and automatic, there was an increased cost involved in holding both ensemble representations simultaneously.