It is an unresolved question whether the posture of single fingers relative to each other is represented in the brain within an external frame of reference. In two experiments, we investigated postural influences on the processing of tactile stimuli at fingers and hands. Healthy subjects received two simultaneous tactile stimuli at the fingertips while the fingers of both hands were either interleaved or not. In speeded response tasks, they were asked to discriminate (experiment 1) or to identify (experiment 2) the touched body parts, either regarding hand laterality or finger type. The results demonstrate that both finger discrimination and finger identification are influenced by body posture. We conclude that the assumption of a solely somatotopic representation of fingers is not tenable and that an external reference system must be available for the detection of single fingers. The results are discussed in terms of a mental segmentation of external space, based on body posture and task requirements.
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Equality judgements require discrimination rather than identification of body parts. To account for these deviant requirements, we will distinguish between identification and discrimination tasks. According to this label distinction, identification tasks were used in Haggard et al. (2006, except experiment. 2), while we will implement discrimination tasks in experiment 1.
This cut-off value is higher than that used in experiment 4 of Haggard et al. (2006) (2000 ms). It accounts for the fact that discrimination tasks require more time than identification tasks (Haggard et al. 2006). The cut-off value of 3000 ms lies within 2.7 standard deviations above the mean of reaction times. Nevertheless, applying different cut-off values (2000 ms and 5000 ms) to the data produced the same results.
Azañón E, Soto-Faraco S (2007) Alleviating the ‘crossed-hands’ deficit by seeing uncrossed rubber hands. Exp Brain Res 182:537–548
Azañón E, Soto-Faraco S (2008) Changing reference frames during the encoding of tactile events. Curr Biol 18:1044–1049
Benedetti F (1985) Processing of tactile spatial information with crossed fingers. J Exp Psychol Hum Percept Perform 11:517–525
Benedetti F (1988) Localization of tactile stimuli and body parts in space: two dissociated perceptual experiences revealed by a lack of constancy in the presence of position sense and motor activity. J Exp Psychol Hum Percept Perform 14:69–76
Craig JC (2003) The effect of hand position and pattern motion on temporal order judgments. Percept Psychophys 65:779–788
Driver J, Grossenbacher PG (1996) Multimodal spatial constraints on tactile selective attention. In: Inui T, McClelland JL (eds) Attention and performance XVI: information integration in perception and communication. MIT Press, Cambridge, MA, pp 209–235
Gigerenzer G, Murray DJ (1987) Cognition as intuitive statistics. Erlbaum, Hillsdale, NJ
Gillmeister H, Sambo CF, Forster B (2010) Which finger? Early effects of attentional selection within the hand are absent when the hand is viewed. Eur J Neurosci 31:1874–1881
Haggard P, Kitadono K, Press C, Taylor-Clarke M (2006) The brain’s fingers and hands. Exp Brain Res 172:94–102
Harrar V, Harris LR (2007) Multimodal Ternus: visual, tactile, and visuo-tactile grouping in apparent motion. Perception 36:1455–1464
Hautus M (1995) Corrections for extreme proportions and their biasing effects on estimated values of d′. Behav Res Meth Instrum Comput 27:46–51
Head H, Holmes G (1911) Sensory disturbances from cerebral lesions. Brain 34:102–254
Kim DH, Cruse H (2001) Two kinds of body representation are used to control hand movements following tactile stimulation. Exp Brain Res 139:76–91
Kitazawa S (2002) Where conscious sensation takes place. Conscious Cogn 11:475–477
Koffka K (1935) Principles of Gestalt psychology. Lund Humphries, London
Lloyd DM, Shore DI, Spence C, Calvert GA (2003) Multisensory representation of limb position in human premotor cortex. Nat Neurosci 6:17–18
Macmillan NA, Creelman CD (1991) Detection theory: a user’s guide. University Press, Cambridge
McFall RM, Treat TA (1999) Quantifying the information value of clinical assessments with signal detection theory. Annu Rev Psychol 50:215–241
Oldfield RC (1971) The assessment and analysis of handedness: the Edinburgh inventory. Neuropsychologia 9:97–113
Overvliet KE, Smeets JB, Brenner E (2010) Serial search for fingers of the same hand but not for fingers of different hands. Exp Brain Res 202:261–264
Pellijeff A, Bonilha L, Morgan PS, McKenzie K, Jackson SR (2006) Parietal updating of limb posture: an event-related fMRI study. Neuropsychologia 44:2685–2690
Röder B, Spence C, Rösler F (2002) Assessing the effect of posture change on tactile inhibition-of-return. Exp Brain Res 143:453–462
Schicke T, Röder B (2006) Spatial remapping of touch: confusion of perceived stimulus order across hand and foot. Proc Natl Acad Sci USA 103:11808–11813
Schicke T, Bauer F, Röder B (2009) Interactions of different body parts in peripersonal space: how vision of the foot influences tactile perception at the hand. Exp Brain Res 192:703–715
Serino A, Giovagnoli G, de Vignemont F, Haggard P (2008) Spatial organisation in passive tactile perception: is there a tactile field? Acta Psychol (Amst) 128:355–360
Shenton JT, Schwoebel J, Coslett HB (2004) Mental motor imagery and the body schema: evidence for proprioceptive dominance. Neurosci Lett 370:19–24
Shibuya S, Takahashi T, Kitazawa S (2007) Effects of visual stimuli on temporal order judgments of unimanual finger stimuli. Exp Brain Res 179:709–721
Shore DI, Spry E, Spence C (2002) Confusing the mind by crossing the hands. Cogn Brain Res 14:153–163
Shore DI, Gray K, Spry E, Spence C (2005) Spatial modulation of tactile temporal-order judgments. Perception 34:1251–1262
Simon JR, Acosta E Jr (1982) Effect of irrelevant information on the processing of relevant information: facilitation and/or interference? The influence of experimental design. Percept Psychophys 31:383–388
Soto-Faraco S, Ronald A, Spence C (2004) Tactile selective attention and body posture: assessing the multisensory contributions of vision and proprioception. Percept Psychophys 66:1077–1094
Zampini M, Harris C, Spence C (2005) Effect of posture change on tactile perception: impaired direction discrimination performance with interleaved fingers. Exp Brain Res 166:498–508
This study was supported by the European Commission within the 6th FP through the SOMAPS research consortium (Project No 043432, www.somaps.eu). Jörg Trojan is indebted to the Baden-Württemberg foundation for the financial support of this research project by the elite programme for postdocs.
The study was approved by the local ethical committee and conducted according to the ethical standards laid down in the 6th Revision of the Declaration of Helsinki (Version Seoul 2008). Furthermore, the authors declare that they have no conflict of interest.
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Riemer, M., Trojan, J., Kleinböhl, D. et al. Body posture affects tactile discrimination and identification of fingers and hands. Exp Brain Res 206, 47–57 (2010). https://doi.org/10.1007/s00221-010-2396-y
- External frame of reference
- Response fields