HGF for Behavioural Analysis: Perceptual Model for Anxiety Patients During Lockdown

Francesco Branca, Davide Menini, Sara Sangalli

Repo tree

• matlab/ --------- matlab code (input generation and postprocessing)
• webapp/ --------- javasript code to create the experiment on webapp
• interface/ ------ interface to handle communication between matlab and webapp (online database handled manually)
• img/ ------------ output images from matlab
• report/ --------- report and presentation

Input generation

1. Generate correct responses u with a generative model. State x_1 obtained from a bernoulli distribution of p(u|cues) and s(x_2)
2. Probability of u given cues as a step function p(u|cues) = (0.1, 0.9, 0.5, 0.1, 0.9)
3. Generative model to generate hidden states x3norm(.), x2norm(.), x1~bern(s(x2), p(u|cues))
4. Cues obtained from a bernoulli distribution of u
5. Correct responses given to the users are noisy, meaning that 10% of the trials are toggled randomly -> increase difficulty
6. Export cues and ground truth to the webapp

Experiment

1. Objective test: biscuits in supermarket A (yes|no) ---> are there biscuits in supermarket B?
2. Subjective test: sanitizers in supermarket A (yes|no) ---> are there sanitizers in supermarket B?
3. Anxiety test: 20 questions ---> 4 levels of anxiety ---> only interested in 2 (anxious or not) = ground truth of patients

• Tests 1 and 2 have the same cues and ground truths
• Tests 1 and 2 ranodmly inverted to avoid side effects (boredom, learning, ...)
• Anxiety test bassed on STAI

Postprocessing

For both test 1 (biscuits) and test 2 (virus):

1. Estimate perceptual parameters om2, om3 and mu3 using tapas_Fit function (tapas_unitsq_sgm_config)
2. Estimate ideal model using bayesian model in tapas_Fit
3. K-Means to cluster the estimations into 2 groups (health controls and anxious patients)
4. Compute score of K-means using the anxiety test as ground truth
5. Compute MSE of users responses using the ideal model as ground truth
6. Correlation between estimated parameters

Conclusions

• Hypothesis verified: lockdown has made people more anxious of not finding sanitizers in supermarkets.