Number of sampling movements and manual stiffness judgments

N. Macfadyen, C. G. Maher*, R. Adams

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Objective: It has been suggested that when using posteroanterior pressure to assess the stiffness of the spine, no more than two or three oscillations should be used. This study sought to examine this clinical impression by investigating the effect of the number of sampling movements on stiffness perception. Design: Perceptual study using a mechanical device to provide stiffness stimuli, with university staff and students as judges. Setting: University psychophysics laboratory. Interventions: In part 1, subjects were directed to sample the stimuli a prescribed number of times (either 1, 2, 3, 4 or 5 pushes), whereas in part 2, subjects were free to choose the number of sampling movements. Main Outcome Measure: Measures of interstimulus discriminability and bias. Results: An inverted-U relationship between the number of directed sampling movements and stiffness discriminability was found, with three cycles providing best discriminability. When subjects were given a choice, most chose to use three cycles. The number of sampling movements had no effect on bias. Conclusion: This study confirms the hypothesis under investigation and suggests that therapists will be maximally sensitive when using three testing cycles of posteroanterior pressure to assess stiffness.

Original languageEnglish
Pages (from-to)604-610
Number of pages7
JournalJournal of Manipulative and Physiological Therapeutics
Issue number9
Publication statusPublished - 1998
Externally publishedYes


  • Palpation
  • Perception


Dive into the research topics of 'Number of sampling movements and manual stiffness judgments'. Together they form a unique fingerprint.

Cite this