Dissociating Slow Responses From Slow Responding

Gayatri Salunkhe, Bernd Feige, Christopher W.N. Saville, Maria Elena Stefanou, David Linden, Stephan Bender, Andrea Berger, Nikolaos Smyrnis, Monica Biscaldi, Christoph Klein

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Increased Intra-Subject Variability (ISV) is a candidate endophenotype of ADHD. ISV’s relationship with response speed is highly relevant for ADHD as patients are highly variable but typically no slower than controls. This brief report addresses the relationship between variability and speed by employing dimensional analyses for differentiated performance measures, with a particular focus on the ex-Gaussian measures, across relevant ADHD studies and in young healthy adults (N = 70). For both patients with ADHD and healthy adults, we found that reaction time standard deviation and mean reaction time were strongly correlated, thus failing to dissociate, but ex-Gaussian tau (τ) shared only little variance with Gaussian mu (μ), thus dissociating slow responses (τ) from response speed or—if given—slow responding (μ). Our results highlight the utility of employing the ex-Gaussian measures to disentangle ISV and speed, particularly for ADHD data as patients make more slow responses but are not overall slower than typical controls.

Original languageEnglish
Article number505800
JournalFrontiers in Psychiatry
StatePublished - 2 Oct 2020


  • attention-deficit/hyperactivity disorder (ADHD)
  • ex-Gaussian modeling
  • intra-subject variability
  • principal components analyses
  • response speed

ASJC Scopus subject areas

  • Psychiatry and Mental health


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