Computerized Text Analysis in Computer-mediated Therapy

The Interapy Post Traumatic Stress Corpus

Jeroen Ruwaard

Corpus Description

4255 texts written by 478 traumatized clients starting online CBT after GP referral for psychotherapy

Demographics, trauma profile, outcome data (pre -

post – 6 week follow-up), process data

Treatment: Web-based CBT

Outcome was good, but not for everyone

Impact of Event Scale

Linguistic Inquiry and Word Count(LIWC)

Calculates the degree to which people use different categories of words - Pennebaker et al. 1993 – Present

I looked inside the car and realised that I knew the face. I had seen him take my teacher to school before. I hesitated a bit. When he saw my hesitation, he said, "Don't you always see this car by your school? I always take some teachers to school. I was relieved and I went into the car. He drove off and while on the way he started a conversation. He asked if I had a boyfriend and I told him no, so he asked why a pretty girl like me didn't have a boyfriend. I told him I was just 14 and was not ready. I became aware that he was looking at me, so I tried to avoid his questions.

Can LIWC detect compliance?

Exposure Reappraisal Closure

Present Past Past / Future

I You I / You

Sense CogMech CogMech

NegEmo PosEmo PosEmo

Example Corpus Data

Reappraisal ClosureExposure

Corpus LIWC ProfileAverage Word Count: 762; 77% words recognized by dictionary

LIWC predicts phase

Phase % of cases correctly classified

1 2 3

Train (n = 250) .85 .80 .64

Test(n = 121) .84 .82 .58

Does LIWC predict outcome?

Word Category

Main effect

Interaction

Linear Quadratic Cubic

I

You

Senses

CogMech

NegEmo

PosEmo

Present

Past

Future

Word Count

p < .01

p < .05

Self-exposure

Summary & Conclusion

LIWC mirrors instructions and intented

therapeutic effects explains small part of the variance in

outcome

More probabilistic approaches of computerized analysis might reveal more