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External Mental Models
Barbara Bazzanella (University of Trento) This page describes an experiment which was designed to explore the experimental elicitation of external models of the premises as a tool to investigate how individuals build models of the premises and how they use them in reasoning. Experimental designBaseline TreatmentPARTICIPANTSWe tested 41 volunteers from VEGA Park in Venezia. The participants were 23 men and 18 women (aged from 25 to 65). For every trial, they were rewarded 1 Euro for the representation task and 1 Euro for the deductive task. DESIGNWe asked participants to build all external models consistent with a set of premises and afterwards to draw a valid conclusion of six problems. The problems concerned features of human faces (e.g. the color of hair, or the presence of a beard).MATERIALSThe six problems are reported below:
Task 1:
If Laura has red hair, then she wears glasses
Task 2:
Either Stefano doesn't have black hair or else he wears a hat
but not both
Task 3:
Antonio wears a hat or he has moustaches - or both.
Task 4:
If Mary wears glasses then she has green eyes.
Task 5:
Either Giorgio has blue eyes or else he smokes a cigar but not both Task 6: Either Luigi has curled hair and he wears glasses or else Luigi has dark eyes and a beard but not both. Luigi has curled hair The experiment was carried out in Italian with Italian native speakers. The premises were printed on a sheet and were administrated one at time. The instructions for the task were briefly summarize at the top of each sheet. On the table used by participants to build models, there were scraps of paper reproducing the empty shape and features of a human face:
PROCEDUREThe participants were tested individually in a quiet room. They were told that the experiment concerned reasoning about a series of deductive problems but that it was not a test of their intelligence. In addition they were told that they would be rewarded in proportion to their performance. Each trial consisted of two phases:
Representation task. For each problem the participants had to
read carefully a first premise and then try to construct all possible
models consistent with the premise. The experimenter showed a practice
problem in order to familiarize the subjects with the experimental
materials. For example, given a premise (from task 1) like: If Laura has red hair then she wears glasses subjects are expected to build three models:
Laura doesn't wear glasses Subjects had to update the models eliminating the all faces which wear
glasses.Consequently, three models were still available: Five problems consisted of two premises and only one (task n°5) consisted of three. The participants could take as much time as they needed to carry out the task. The participants begun the proper experiment after he had asked any questions about the task and were certain that they understood it. Control TreatmentPARTICIPANTSWe tested individually 44 volunteers ( 23 women and 21 men). They ranged in age from 19 and 65 years. Individuals didn't receive monetary reward. MATERIALS and PROCEDUREThe participants were tested individually in a quite room. They were told that they were taking part in an experiment on deductive reasoning. Their task was to considers six problems and, for each of them to draw a conclusion (if they thought that there was one) that had to be true given that the premises were true. The subjects were presented the same six problems of baseline treatment and asked to draw a conclusion without having to construct any external representation. Each set of premises was printed on a separated page of paper and the participants wrote their answers beneath the premises. The experiment was carried out in Italian with native speakers of that language. The original materials are available here. Subjects were allowed to take as much time as they needed. On an average the task lasted 20 minutes.
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2001 - Università degli Studi di Trento |