The Dynamics of Psychology

  • Psychological constructs can be conceptualized as dynamical systems, featuring complex emergent behavior:
    • Correlated responses
    • Stable "traits"
    • Phase transitions
    • Individual Differences
  • These systems can be portrayed as networks


Van der Maas et al. (2006)

Psychopathology as a virus


The Ising Model

Network Psychometrics

  • What is the structure of psychology?

Three flavors of network analysis

  • Cross-sectional analysis
    • Portrays pairwise effects and conditional independences in a dataset between persons
    • Undirected networks or directed acyclic networks
  • \(N=1\) longitudinal analysis
    • Shows the intra-individual dynamics of a single person
    • Temporal (directed) and contemporaneous (undirected) networks
  • \(N>1\) longitudinal analysis (multi-level)
    • Shows general intraindividual dynamics as well as size of inter-individual differences
    • Temporal (directed) networks

Example 1: Cross-sectional network analysis of personality traits

  • \(B\) separates \(A\) and \(C\)
  • \(A \!\perp\!\!\!\perp C \mid B\)

  • A well accepted approach for jointly model selection and parameter estimation is the least absolute shrinkage and selection operator (LASSO)
    • Penalized maximum likelihood estimation
  • LASSO utilizes a penalty parameter, which can be chosen to optimize some information criterion
    • Extended Bayesian information criterion (EBIC)

Cross-sectional network analysis

  • Binary data:
    • LASSO: IsingFit (
    • No LASSO: IsingSampler (
  • Multivariate normal data:
    • LASSO: qgraph with option graph = "glasso"
    • No LASSO: qgraph with option graph = "pcor"

Emperical example: personality

I will analyze the BFI dataset from the pych package:

  • 25 items
  • 2800 subjects
  • Five items for each of the five central personality traits


Am indifferent to the feelings of others.

Inquire about others' well-being.

Know how to comfort others.

Love children.

Make people feel at ease.


Am exacting in my work.

Continue until everything is perfect.

Do things according to a plan.

Do things in a half-way manner.

Waste my time.


Don't talk a lot.

Find it difficult to approach others.

Know how to captivate people.

Make friends easily.

Take charge.


Get angry easily.

Get irritated easily.

Have frequent mood swings.

Often feel blue.

Panic easily.

Openess to Experience

Am full of ideas.

Avoid difficult reading material.

Carry the conversation to a higher level.

Spend time reflecting on things.

Will not probe deeply into a subject.