Computational analyses of linguistic features with schizophrenic
and autistic traits along with formal thought disorder
Takeshi Saga, Hiroki Tanaka, Satoshi Nakamura
Nara Institute of Science and Technology

4. Between questionnaire correlation (Q1)

0. Summary

Spearman correlation

Motivation: formal thought disorders (FTD), common
symptoms in ASD/Schizophrenia, well-known but why/how?
Objective:- find how schizotypal/autistic-traits correlated- find suitable FTD elicitation conditions

SPQ

SPQ

OddSpeech

SRS

1.00

0.28

0.01

1.00

0.32

OddSpeech

Method: correlation analysis and regression analysis
Result:- Schizotypal/autistic-traits are correlated along with FTD axis
- Long speech about negative memories is better elicitation- Embedding/content-word features are symptom-specificDataset/code available athttps://sites.google.com/view/sagatake/resource

1. Formal Thought Disorder (FTD)
Symptoms in cognition affecting to language, thought content- Disorder of form (disorganization), not content (delusion)- One of Schizophrenia(SZ)’s main symptoms- Observed in other mental/developmental disorders, e.g., ASD
Negative thought disorderPoverty of speech, etc.

Resultsa) SPQ didn’t correlate with SRSb) OddSpeech correlated withboth of SRS and SPQ

OddSpeech (≅FTD) seems a bridge between SPQ and SRS

5-0. Prediction method and input features
Model: PLS regression, selected to eliminate multi-collinearity
Cross validation:- Outer loop: leave-one-participant-out, for individuality effect- Inner loop: 5-fold, to optimize #component, from 1 to 10
Feature groups:- Embedding: BERT sent. diff. /cosine, content-word cosine- Content word : ratio of content words (noun, verb, etc.)- Function word : ratio of function words (pronoun, etc.)- Abstract: ratio of content word, CDI-J, negation freq.
- Temporal: word per minute, punctuation ratio
Evaluation: Spearman’s correl. with true scores and predictions

5-1. Task comparison (Q2)

Positive thought disorder
Derailment, Illogicality, etc.

Spearman true-pred correlation
Dream

D. A. Trevisan et al., “Autism spectrum diorder and schizophrenia are better
differentiated by positive symptoms than negative symptoms”, frontiers inpsychiatry, 2020

2. Related work: FTD-related estimation
Silva et al. 2021
• 1 min. picture-description task
• CDI (combination of part of speech)
correlated with FTD severity
Tang et al. 2021
• 12 min. interview• SZ’s sent. embed. distance increased
with #responses to a question
Difficult to compare effectiveness due todifferent speech durations and tasks

3. Data collection

SPQ

OddSpeech

SRS

0.01 → -0.24-0.24 → -0.24

0.34* → -0.54*

Favorite-0.42* → -0.35* -0.24* → -0.14 -0.25* → -0.27*

Negative0.23* → 0.22*

0.20* → 0.26*

0.25* → 0.22*

Mistake0.05 → -0.07

0.08* → 0.18*

0.30 → 0.15

Negative memory works well
- Minor et al. showed positive
FTD symptoms are associatedwith affective systems in brain- “Negative” induce FTD more

K. S. Minor et al., “Affective systems induce formal thought disorder in early-stage psychosis”, Journal of Abnormal Psychology, 2016

5-2. Duration comparison (Q3)
Spearman true-pred correlation
30 sec60 sec180 sec

30sec.

60sec.

180sec.

SPQ

0.01 → 0.08

0.21 → 0.20

0.15 → 0.06

OddSpeech

0.15 → 0.17

0.20 → 0.21

0.23 → 0.37*

SRS

0.27 → 0.30

0.36* → 0.07

0.24 → 0.19

divided 180 sec. speech into 0-60, 60-120, 120-180
Spearman true-pred correlation
0-60

60-120120-1800-60sec.

60-120sec.

120-180sec.

SPQ-0.15 → 0.09

0.00 → -0.02

0.24 → 0.20

OddSpeech-0.08 → 0.03

0.07 → 0.14

0.37* → 0.40*

SRS

0.33* → 0.36*

0.02 → 0.02

0.28 → 0.27

OddSpeech performance increase as speech goes latter part
- Not because of algorithms but how long participants speak

Method: Audio + crowd-sourcing + questionnaire

5-3. Ablation study (Q4)

Participant: 54 people from general population
Procedure: talk about a given theme for 30, 60, 180 seconds- ”Recent dream” or “favorite thing”- “Negative memory”- “Biggest mistake”
Questionnaires (partial):- Schizotypal Personality Questionnaire (SPQ) for SZ-trait> Subscale: ”Odd speech” related to FTDs
- 2nd edition of Social Responsiveness Scale (SRS2) for ASD-trait

SPQ (SZ)
SPQ
OddSpeechSRS- Function-word and embedding
full
0.23* → 0.18* 0.2* → 0.21* 0.26* → 0.25*
SRS (ASD)
w/o embed. 0.23* → 0.12 0.22* → 0.19* 0.17* → 0.24*
w/o cont.
0.22* → 0.17* 0.23* → 0.23* 0.23* → 0.18
Function-wordandcontent-word
w/o func.
0.13 → 0.09 0.05 → 0.04 0.18 → 0.09
OddSpeech (FTD)
w/o abst.
0.21* → 0.19* 0.2* → 0.24* 0.28* → 0.19*
w/o temp. 0.24* → 0.19* 0.21* → 0.17* 0.28* → 0.28*- Function-word and temporal
Feature-set effectCommon: function word, FTD-specific: temporal

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