Advertisement

Experimental Brain Research

, Volume 236, Issue 8, pp 2439–2446 | Cite as

Hand anthropometry and the limits of aperture separation determine the utility of Weber’s law in grasping and manual estimation

  • Naila Ayala
  • Gordon Binsted
  • Matthew Heath
Research Article

Abstract

Recent work proposed that biomechanical constraints in aperture separation limit the utility of Weber’s law in determining whether dissociable visual codes support grasping and manual estimation. We tested this assertion by having participants precision grasp, manually estimate and complete a method of adjustment task to targets scaled within and beyond the range of their maximal aperture separation (i.e., from 20 to 140% of participant-specific maximal aperture separation: MAS). For grasping and manual estimation tasks, just-noticeable-difference (JND) scores were computed via the within-participant standard deviations in peak grip aperture, whereas method of adjustment JNDs were computed via the within-participant standard deviations in response output. Method of adjustment JNDs increased linearly across the range of targets; that is, responses adhered to Weber’s law. Manual estimation JNDs linearly increased for targets 20–100% of MAS and then decreased for targets 120–140% of MAS. In turn, grasping JNDs for targets 20% through 80% of MAS did not differ and were larger than targets 100–140% of MAS. That manual estimation and grasping showed a decrease in JNDs for the largest targets indicates that participants were at their biomechanical limits in aperture shaping, and the fact that the target showing the JND decrease differed between tasks (i.e., manual estimation = 100% of MAS; grasping = 80% of MAS) is attributed to the fact that grasping—but not manual estimation—requires a safety-margin task-set. Accordingly, manual estimations and grasping across a range of functionally ‘graspable’ targets, respectively, adhered to and violated Weber’s law—a result interpreted to reflect the use of dissociable visual codes.

Keywords

Grasping Manual estimation Perception Psychophysics Weber’s law 

Notes

Acknowledgements

Supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (MH) and Faculty Scholar and Major Academic Development Fund Awards from the University of Western Ontario.

Compliance with ethical standards

Conflict of interest

The authors declare no commercial, financial or other conflict of interest.

References

  1. Baird JC, Noma EJ (1978) Fundamentals of scaling and psychophysics. Wiley, New YorkGoogle Scholar
  2. Brainard DH (1997) The psychophysics toolbox. Spat Vis 10:433–436CrossRefPubMedGoogle Scholar
  3. Bruno N, Uccelli S, Viviani E, de’Sperati C (2016) Both vision-for-perception and vision-for-action follow weber’s law at small object sizes, but violate it at larger sizes. Neuropsychologia 91:327–334CrossRefPubMedGoogle Scholar
  4. Bryden MP (1977) Measuring handedness with questionnaires. Neuropsychologia 15:617–624CrossRefPubMedGoogle Scholar
  5. Fitts PM (1954) The information capacity of the human motor system in controlling the amplitude of movement. J Exp Psychol 47:381–391CrossRefPubMedGoogle Scholar
  6. Franz VH (2003) Manual size estimation: a neuropsychological measure of perception? Exp Brain Res 151:471–477CrossRefPubMedGoogle Scholar
  7. Ganel T. Chajut E, Algom D (2008a) Visual coding for action violates fundamental psychophysical principles. Curr Biol 18:R599–R601Google Scholar
  8. Ganel T, Chajut E, Tanzer M, Algom D (2008b) Response: when does grasping escape Weber’s law? Curr Biol 18:R1090–R1091Google Scholar
  9. Ganel T, Namdar G, Mirsky A (2017) Bimanual grasping does not adhere to Weber's law. Sci Rep 7:6467CrossRefPubMedPubMedCentralGoogle Scholar
  10. Gescheider GA (2013) Psychophysics: the fundamentals, 3rd edn. Lawrence Erlbaum, LondonGoogle Scholar
  11. Goodale MA, Milner AD (1992) Separate visual pathways for perception and action. Trends Neurosci 15:20–25CrossRefPubMedGoogle Scholar
  12. Heath M, Manzone J, Khan M, Davarpanah Jazi S (2017) Vision for action and perception elicit dissociable adherence to weber’s law across a range of ‘graspable’ target objects. Exp Brain Res 235:3003–3012CrossRefPubMedGoogle Scholar
  13. Holmes SA, Heath M (2013) Goal-directed grasping: the dimensional properties of an object influence the nature of the visual information mediating aperture shaping. Brain Cogn 82:18–24CrossRefPubMedGoogle Scholar
  14. Holmes SA, Mulla A, Binsted G, Heath M (2011) Visually and memory-guided grasping: aperture shaping exhibits a time-dependent scaling to weber’s law. Vis Res 51:1941–1948CrossRefPubMedGoogle Scholar
  15. Jeannerod M (1984) The timing of natural prehension movements. J Mot Behav 16:235–254CrossRefPubMedGoogle Scholar
  16. Keppel G (1991) Design and analysis: a researcher’s handbook. Prentice Hall, Englewood CliffsGoogle Scholar
  17. Marks LE, Algom D (1998) Psychophysical scaling. In: Birnbaum MH (ed) Measurement, judgment, and decision making. Academic Press, San Diego, pp 81–178CrossRefGoogle Scholar
  18. Marteniuk RG, MacKenzie CL, Jeannerod M, Athenes S, Dugas C (1987) Constraints on human arm movement trajectories. Can J Psychol 41:365–378CrossRefPubMedGoogle Scholar
  19. Mckee SP, Welch L (1992) The precision of size constancy. Vis Res 32:1447–1460CrossRefPubMedGoogle Scholar
  20. Pedhazur EJ (1997) Multiple regression in behavioral research: explanation and prediction, 3rd edn. Harcourt Brace College Publishers, OrlandoGoogle Scholar
  21. Pheasant ST (1986) Bodyspace: anthropometric ergonomics and design. Taylor and Francis, LondonGoogle Scholar
  22. Schmidt RA, Zelaznik H, Hawkins B, Frank JS, Quinn JT (1979) Motor-output variability: a theory for the accuracy of rapid motor acts. Psychol Rev 47:415–451CrossRefPubMedGoogle Scholar
  23. Smeets JB, Brenner E (1999) A new view on grasping. Mot Control 3:237–271CrossRefGoogle Scholar
  24. Smeets JB, Brenner E (2008) Grasping weber’s law. Curr Biol 18:R1089–R1090CrossRefGoogle Scholar
  25. Utz KS, Hesse C, Aschenneller N, Schenk T (2015) Biomechanical factors may explain why grasping violates weber’s law. Vis Res 111:22–30CrossRefPubMedGoogle Scholar
  26. Westwood DA, Chapman CD, Roy EA (2000) Pantomimed actions may be controlled by the ventral visual stream. Exp Brain Res 130:545–548CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.School of Kinesiology and Graduate Program in NeuroscienceUniversity of Western OntarioLondonCanada
  2. 2.Faculty of Health and Social DevelopmentUniversity of British ColumbiaKelownaCanada

Personalised recommendations