Weights in Visuo-Haptic Softness Perception are not Sticky

  • Knut DrewingEmail author
  • Onno Kruse
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8618)


The contribution of vision to visuo-haptic softness judgments has been observed to be non-optimal and it has been speculated that the visual weights are “sticky”, i.e., do not account for the senses’ reliabilities [1, 2]. The present study tested the hypothesis of sticky weights by varying the quality of the visual information. Participants discriminated between the softness of two objects with deformable surfaces using only visual, only haptic, or bisensory information. Visually, we displayed the finger’s positions and stimulus deformations in a noisy or precise quality or in a precise quality enhanced by visual force information from color changes of the finger nail. We assessed the reliabilities of the judgments using the method of constant stimuli. In bisensory conditions, discrepancies between the two senses’ information were used to measure each sense’s weight. The reliability of visual judgments was lower with noisy as compared to precise position information, visual force information did not affect reliability. The reliability of bisensory judgments was suboptimal and visual weights were higher than optimal. Not as expected, the visual weights shifted with the visual reliability. The results confirm that visuo-haptic integration of softness information is suboptimal and biased towards vision, but with weights that are “lazy” rather than sticky.


Softness Multisensory Visuo-haptic Psychophysics 


  1. 1.
    Cellini, C., Kaim, L., Drewing, K.: Visual and Haptic integration in the estimation of softness of deformable objects. i-Perception 4, 516–531 (2013)CrossRefGoogle Scholar
  2. 2.
    Kuschel, M., DiLuca, M., Buss, M., Klatzky, R.: Combination and integration in the perception of visual-haptic compliance information. Trans. Haptics 3, 234–244 (2010)CrossRefGoogle Scholar
  3. 3.
    Ernst, M.O., Bulthoff, H.H.: Merging the senses into a robust percept. Trends Cogn. Sci. 8, 162–169 (2004)CrossRefGoogle Scholar
  4. 4.
    Gepshtein, S., Burge, J., Ernst, M.O., Banks, M.S.: The combination of vision and touch depends on spatial proximity. J. Vis. 5, 1013–1023 (2005)CrossRefGoogle Scholar
  5. 5.
    van Beers, R.J., Sittig, A.C., Gon, J.J.: Integration of proprioceptive and visual position-information: An experimentally supported model. J. Neurophysiol. 81, 1355–1364 (1999)Google Scholar
  6. 6.
    Alais, D., Burr, D.: The ventriloquist effect results from near-optimal bimodal integration. Curr. Biol. 14, 257–262 (2004)CrossRefGoogle Scholar
  7. 7.
    Landy, M.S., Maloney, L.T., Johnston, E.B., Young, M.: Measurement and modeling of depth cue combination: In defense of weak fusion. Vision. Res. 35, 389–412 (1995)CrossRefGoogle Scholar
  8. 8.
    Rosas, P., Wagemans, J., Ernst, M.O., Wichmann, F.A.: Texture and haptic cues in slant discrimination: Reliability-based cue weighting without statistically optimal cue combination. J. Opt. Soc. Am. A 22, 801–809 (2005)CrossRefGoogle Scholar
  9. 9.
    Mascaro, S.A., Asada, H.H.: Photoplethysmograph fingernail sensors for measuring finger forces without haptic obstruction. Trans. Robot. Autom. 17, 698–708 (2001)CrossRefGoogle Scholar
  10. 10.
    Kaim, L., Drewing, K.: Exploratory strategies in haptic softness discrimination are tuned to achieve high levels of task performance. Trans. Haptics 4, 242–252 (2011)CrossRefGoogle Scholar
  11. 11.
    Wichmann, F.A., Hill, N.J.: The psychometric function: I. Fitting, sampling, and goodness of fit. Percept. Psychophys. 63, 1293–1313 (2001)CrossRefGoogle Scholar
  12. 12.
    Tan, H.Z., Durlach, N.I., Beauregard, G.L., Srinivasan, M.A.: Manual discrimination of compliance using active pinch grasp: The role of force and work and cues. Percept. Psychophys. 57, 495–510 (1995)CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Justus-Liebig-University GiessenGiessenGermany

Personalised recommendations