Accuracy of the baseline (circles) and the expert (triangles) models in classifying deceptive (solid) and normal (dashed) data, as a function of the number of training subjects.

<p>Dotted line shows the chance level (50%) and the shaded areas show standard deviation of the accuracies.</p

Average success rate of subjects in walking and sitting trials, indicating how successful they are at cheating.

<p>Each colored dot represents a subject’s success rate at a trial. The dots which are not connected to any line belong to subjects who failed in the first deceptive activity trial.</p

Difference (%) between the accuracy of the expert and the baseline classifiers, when varying number of training subjects is used.

<p>Each gray line shows the accuracy difference when one subject’s deceptive data is used as test, and the black line shows the average and its standard deviation as error bars. In all tests the expert classifiers perform better than the baseline classifiers (the difference is positive). While the relationship between the accuracies and the number of training subjects is noisy, it does not vary much for each test dataset.</p

Experiment design overview.

<p>Each trial consisted of two types of activities: walking and sitting.</p

Difference (%) between the accuracy of the expert and the baseline classifiers, when varying number of training subjects is used.

<p>Each gray line shows the accuracy difference when one subject’s deceptive data is used as test, and the black line shows the average and its standard deviation as error bars. In all tests the expert classifiers perform better than the baseline classifiers (the difference is positive). While the relationship between the accuracies and the number of training subjects is noisy, it does not vary much for each test dataset.</p

2-dimensional representation of feature values collected from a single subject who succeeded in 3 trials.

<p>We used a 2-component factor analysis. Green circles show normal activity and grey crosses indicate fake activity factors. The changing location of fake activity data points across trials shows different strategies taken by the subject.</p