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Cognitive Neuroscience (Subject) / Haptics (Lesson)
Haptics - done
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- What is the relationship between touch and proprioception? How can this be studied? Name two studies as an example. Touch and proprioception are seperate modalities. The location of a touch on the skin (somatotopic representation) is combined with information about the location of the limb in space (proprioception), resulting in a representation of touch in "external space". This process takes abut 200-300msec. Yamamoto & Kitazawa (2001): Reversal of subjective temporal order due to arm crossing. TOJ-Task: When the stimulation interval is short (under 300ms) subjects show impaired performance. In some subjects to an extend where the wrong answer is given more often than chance level. Performance improves with length of time interval. Overvliet et al. (2013): Somatosensory saccades reveal the timing of spatial remapping. TOJ-Task with saccade as response: When hands are crossed subjects need more time for correct saccade response. Curved saccades reflect initial errors that are corrected with time.
- How does the representation of the fingers differ from that of the hands? What illusions can be used to demonstrate that (two)? Name example studies (four). Recording into external space occurs only for hand identification.Finger identification is achieved using a somatotopic representation. Fingers are always perceived in a "prototypical configuration". Van Riper (1935): Japanese Illusion; Hayward (2008): Aristotele Illusion. Benedetti (1985): Processing of tactile spatial information with crossed fingers. The perceived relative orientation of the fingers was never more than as if they were on top of each other, even when one finger was turned maximally around the other (crossed). Haggard et al. (2006): The brain's fingers and hands. Longer RTs and more errors in woven condition (compared to ertical posture) for hand but not for finger identification. Finger-crossed TOJ-task: crossing the fingers results in wrong answers for all SOAs! Overvliet et al. (2011): Relative finger position influences whether you can localize tactile stimuli. "Fingers spread" yielded fewer errors than "fingers together" and "fingers interwoven". However, most of the errors are made within a finger, and no differences in distribution were found. Spreading the fingers makes them more "distinct", but no evidence for purely spatial encoding is found.
- How is information processed over the fingers? (5 studies) Overvliet et al. (2007): Parallel and serial search in haptics. --> Serial search pattern. Fingers are seperate sensors and cannot process information at the same time unless stimuli characteristics are very different (e.g. no stimulus vs. stimulus). Overvliet et al. (2008): Haptic search is more efficient when the stimulus can be interpreted as consisting of fewer items. Number of fingers determines search time. However, search is more efficient when the stimulus can be interpreted as consisting of fewer items (also serial pattern but overall search time is smaller). Overvliet et al. (2007): Haptic search with finger movements: Using more fingers does not necessarily reduce search times. Effects of stimulus distance and number of fingers from same hand on search time. The bigger the distance between stimuli, the longer it takes (hopping, netto search time w finger on target the same). The more fingers used, the longer it takes (serial processing + switching costs). Overvliet et al. (2010): Serial search for fingers of the same hand but not for fingers of different hands. Overvliet et al. (2012): Perceptual grouping in haptic search. Tactile information processing is serial over the fingers within a hand, except when the information on the fingers can be "grouped" or interpreted as one object.
- What is the Image Mediation Model? Name a study that verified the model. The Image Mediation Model proposed by Klatzky & Ledeman (1987) states that input from haptic sensors is visually translated to a visual image that allows object recognition. Overvliet et al. (2013): Recognition of tactile diagrams better in young vs. old people. Improves with visual mediation (vision, drawing after touching) and when context is given.
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