Sensory Feedback using Electrical Stimulation of the Tactile Sense
Raymond V. Smith, John H. Leslie in Rehabilitation Engineering, 2018
Generally, the JND is specified as the minimum difference in the stimulus that is correctly detected on 75% of the test trials. That level of discriminability of the stimuli is actually rather poor since it implies that 25% of the messages sent are interpreted incorrectly. Using JNDs to separate message units, the average information transferred would thus be relatively low. If a more stringent criterion for the size of the JND is used, perhaps 90 or 95% discriminability, then substantial gains in information transfer might be possible in exchange for such wider spacing between messages and hence a much wider stimulus range. Unfortunately, specific experiments that focus directly on information transferred for electrocutaneous codes as a function of stimulus separation have not been reported.
Psychophysical Measurement of Human Oral Experience
Alan R. Hirsch in Nutrition and Sensation, 2023
Thresholds have been used for sensory evaluation ever since Fechner described them in his Elemente der Psychophysik (Fechner 1860/1966), one of the first published works of experimental psychology. Although thresholds present both conceptual and practical challenges (e.g., Engen 1972; Lawless and Heymann 2010), their basic definition is straightforward: The absolute or detection threshold for a stimulus is the lowest concentration at which its presence can be detected as something, whether or not its quality can be determined. The recognition threshold, which is often slightly higher than absolute threshold, is the lowest concentration at which the primary quality of a stimulus (e.g., sweet, painful) can be identified. Finally, the difference threshold is the smallest increase in suprathreshold stimulus concentration that can be detected (i.e., the “just noticeable difference” or jnd). Clinical assessments of gustatory function typically focus on the absolute threshold, while food and consumer scientists often use difference thresholds to evaluate flavor changes or off-tastes.
Augmenting Haptic Perception in Surgical Tools
Terry M. Peters, Cristian A. Linte, Ziv Yaniv, Jacqueline Williams in Mixed and Augmented Reality in Medicine, 2018
To investigate how the HHFM affected the perceptual system, psychophysical experiments were conducted to address three fundamental questions (Stetten et al. 2011; Wu et al. 2015): (1) How does magnification affect the minimum force that can be detected? To answer, we measured users’ absolute force threshold. (2) How does magnification affect the minimum difference between forces that can be discriminated? To answer, we measured users’ just-noticeable-difference (JND). (3) How does magnification affect the perceived magnitude of force and mechanical stiffness? To answer, we asked users to report subjective magnitudes over a range of physical values. The perceptual experiments were performed with the HHFM Model-1 connected to a Butterfly Haptics Maglev 200, a six-DoF haptic device capable of actuating forces as high as 40 N. In all experiments, participants were tested under three conditions: HHFM-on (active magnification of actuated forces), where the HHFM gain was set to k = 2.4, so the overall perceptual gain as determined from Equation 18.2 was 3.4; HHFM-off, in which participants wore the HHFM but magnification was turned off; and control, where participants used a 1-mL syringe, which was identical to the handle of the HHFM Model-1, to contact the MLHD handle. Each experiment began with the tool resting on the handle, as shown in Figure 18.3.
Survey of selective electrode deactivation attitudes and practices by cochlear implant audiologists
Published in Cochlear Implants International, 2023
Kara L. Sander, Sarah E. Warren, Lisa Lucks Mendel
Evidence supports the need for optimized programming in order to resolve patients’ sound quality complaints, thus resulting in a higher likelihood of increased speech perception outcomes. Objective methods available to identify poorly encoded electrodes include CT-guided imaging (Noble et al., 2016; Labadie and Noble, 2018; Danieli et al., 2021), mismatch negativity (MMN) (Mathew et al., 2018), and spatial auditory change complex (ACC) (Mathew et al., 2018). For patients who cannot provide reliable behavioral responses, such objective methods may be appropriate. Post-operative CT scans provide valuable information regarding the location of the electrode array, and this information can be used to create individualized programs by deactivating poorly placed electrodes (Labadie and Noble, 2018). Cortical evoked potentials, such as spatial ACC and MMN, can also be used to infer about electrode pitch encoding by assessing whether a stimulus change is detected at the level of the cortex, however, these methods show a weak correlation with behavioral electrode discrimination (Mathew et al., 2017). Because device programming relies heavily on subjective input from the patient, perhaps the most appropriate approach to selective electrode deactivation is utilization of a psychophysical, behavioral method. Compared to objective methods, subjective behavioral tasks may possess greater clinical feasibility compared to objective measures which require additional software, equipment, and specialized training. Such methods include electrode discrimination, pitch ranking, just noticeable difference threshold, and masked modulation detection (Sagi and Svirsky, 2018).
Instant vision assessment device for measuring refraction in low vision
Published in Clinical and Experimental Optometry, 2021
Moreover, in refracting low vision patients, there are no reliable ways to predict sensitivity to dioptric changes even though tolerance to defocus is known to increase as visual acuity decreases.4 Some patients with 6/60 vision will confidently and reliably notice 0.50 D changes, whereas others with the same acuity will have great difficulty discriminating between changes of 2.00 D.17 Therefore, SR usually starts with large dioptric changes and progressively reduces the amount of changes to find the just noticeable difference.
Tactile-Based Pantomime Grasping: Knowledge of Results is Not Enough to Support an Absolute Calibration
Published in Journal of Motor Behavior, 2019
Matthew Heath, Jillian Chan, Shirin Davarpanah Jazi
Recent work by our group has adapted the memory-guided visual pantomime-grasping task to examine perception/action dissociations in the somatosensory domain (Davarpanah Jazi & Heath, 2014; Davarpanah Jazi, Hosang, & Heath, 2015a; see also Anema, Wolswijk, Ruis, & Dijkerman, 2008). Naturalistic tactile grasps require that a participant hold a target that fits in the palm of their non-grasping (i.e., the left) hand and reach to grasp it with their opposite (i.e., right) hand, whereas pantomime-grasps require that the target object is removed from the non-grasping hand prior to grasping onset (i.e., memory-guided). In both conditions, participants are precluded from seeing the target object or the grasping environment. As a result, the size of the target is defined – and the movement is planned – entirely on the basis of mechanical deformation of the skin (i.e., tactile feedback). Such a procedure is therefore distinct from visually based pantomime grasps in that it provides a framework for examining perception-action dissociations in somatosensory processing. Additionally, our group computed the just-noticeable-difference (JND) scores associated with naturalistic and pantomime-grasps to examine whether the conditions differentially adhered to – or violated – Weber's law (for extensive review see Marks & Algom, 1998). Weber's law asserts that the JND associated with perceiving a change between an original (e.g., target object) and a comparator (e.g., grip aperture) stimulus is in constant proportion to the magnitude of the original stimulus, and that the sensitivity of detecting a change in any physical continuum is relative and not absolute (for reviews of Weber's law in grasping see Ganel, Chajut, & Algom, 2008; Heath, Davarpanah Jazi, & Holmes, 2015). The results for PGA mirrored those reported in the visual domain, and JNDs for naturalistic and pantomime-grasps violated and adhered to Weber's law, respectively. Results were interpreted as evidence that tactile-based naturalistic grasps are supported by absolute target size information, whereas pantomime-grasps are subserved via relative target size information.
Related Knowledge Centers
- Experimental Psychology
- Sense
- Perception
- Psychophysics
- Limen
- Weber–Fechner Law
- Stevens'S Power Law
- Detection Theory
- Psychological Distance
- Beat