Siegler and Shrager (1984) describe an experiment where we can illustrate these partial-matching ideas at work. They asked 4-year olds to retrieve the sums to various addition problems that had addends from 1 to 5. Partial matching involves misretrieval of chunks and it is unclear whether all of these children had chunks for problem with addends greater than 3. Therefore we will only focus on the problems from 1+1 to 3+3.
Microsoft Excel Spreadsheet of Model
Note:
There is a discrepancy between the predictions of the Spreadsheet version of the model, and the running ACT-R model. The Spreadsheet version assumes variability in the threshold, but ACT-R has a fixed threshold. This shows up in the underprediction of 'other' responses by the ACT-R model. The predictions in the book come from the Excel model.