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Building a Set of Items for Measurement
Published in Trevor G. Bond, Zi Yan, Moritz Heene, Applying the Rasch Model, 2020
Trevor G. Bond, Zi Yan, Moritz Heene
As a convenient starting point for the mapping process, the mean of the item difficulties is adopted by default as the 0 point. In this case, ignoring the error of measurement for a moment, Item 4 is calculated as being at the mean of the item difficulty estimates, so it is ascribed an estimate of 0.0 logits and is located at the 0 point on the item–person map. The rest of the items are spread above and below 0 to represent their difficulties relative to Item 4’s 0 logits. Remember that interval-level measurement scales (e.g., °C) have their origin points assigned arbitrarily by convention (e.g., freezing point of water); for Rasch scales, the mean of the item difficulties is usually adopted as the zero scale origin. Person locations arethen plotted so that any person has a 50% probability of succeeding with an item located at the same point on the logit scale. For example, a person with an ability estimate of 0 logits has a 50% probability of succeeding (or failing) on Item 4. That same person would have a greater than 50% chance of succeeding on items less difficult than Item 4 (say, Items 10, 29, and 5) and less than a 50% probability of succeeding on items that are more difficult than Item 4 (say, Items 17, 25, and 26). The 50% limen, or threshold, is adopted routinely in Rasch analysis, although some Rasch software allows for variations from this value to be specified. For example, those committed to the concept of mastery learning might want to use the 80% threshold that is used routinely in that field to indicate mastery.
Pitch and timbre
Published in Stanley A. Gelfand, Hearing, 2017
In this chapter we will deal with several attributes of sounds grossly classified as pitch, along with several associated topics. Like “loudness,” the word “pitch” denotes a perception with which we are all familiar. Pitch is generally described as the psychological correlate of frequency, such that high-frequency tones are heard as being “high” in pitch and low frequencies are associated with “low” pitches (ANSI, 2004). However, we saw in Chapter 9 that not all changes in frequency are perceptible. Instead, a certain amount of frequency change is needed before the difference limen (DL) is reached. In other words, the frequency difference between two tones must be at least equal to the DL before they are heard as being different in pitch. Moreover, we shall see that pitch does not follow frequency in a simple, one-to-one manner along a monotonic scale from low to high. Instead, the perception of pitch appears to be multifaceted, and it may be that there are various kinds of pitch. In addition, although we know that pitch involves both the place and temporal mechanisms of frequency coding discussed in earlier chapters, the precise interaction of frequency and temporal coding is not fully resolved.
Discussions (D)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
One may then ask whether this “threshold” is part of the insula or instead an area that must be traversed to “enter” the insula. Most of the authors cited above describe the limen insulae in a paragraph or section dealing strictly with the insula, and their phrasing further suggests that they consider it to be part of the insula. Barr and Kiernan, for example, state that “The inferior part of the insula in the region of the stem of the lateral sulcus is known as the limen insulae” (1983, p. 217). There are exceptions, however. For example, Carpenter and Sutin describe the limen insulae as “The opening leading to the insular region” (1983, p. 32); and Crosby, Humphrey, and Lauer (1962) describe it as “The rostral approach to the island [= insula]” (p. 344). The latter authors are inconsistent in this regard, however, for they elsewhere state that “The insula … has somewhat the shape of a tennis racket, … with the handle extending frontally to constitute the limen of the island” (p. 476).
The relationship between health related quality of life and sensory deficits among patients with diabetes mellitus
Published in Disability and Rehabilitation, 2018
Batya Engel-Yeger, Sanaa Darawsha Najjar, Mahmud Darawsha
The Tactile Discrimination Test (TDT) [25] this quantitative measure examines tactile discrimination by detecting the ability to discriminate between different textures. It includes graded plastic surfaces marked by ridges at set spatial intervals. Five different triplets, spanning Weber ratios of 0.033–1.0, were each presented ten times in random order to obtain the discrimination limen. The limen was derived from fitting a cumulative normal distribution to the probabilities of correct responses. Texture grids were presented in sets of three, with two surfaces identical and one different. Participants tactually explored each set of comparison surfaces with their index and indicated the odd texture in a three-alternative, forced-choice design. The TDT has high retest reliability, good discriminative validity and normative standards [25,26].
When cooling of the skin is perceived as warmth: Enhanced paradoxical heat sensation by pre-cooling of the skin in healthy individuals
Published in Temperature, 2023
Ellen L. Schaldemose, Niels T. Andersen, Nanna B. Finnerup, Francesca Fardo
The study design was cross-sectional and consisted of a single session. Participants’ thermal sensitivity and presence of PHS were tested using standardized QST measures [2,15], as well as a modified thermal sensory limen protocol. All tests were administered by the same investigator (ELS) for all participants and were performed on the dorsum of either foot. The location was chosen to match the body area that typically exhibits altered sensitivity in patients with diabetic polyneuropathy [27]. To account for variations in skin temperature [28,29] and to maintain a constant and equal skin temperature, the feet were warmed with a heating lamp to 32 ± 0.5°C during the tests and the skin temperature was monitored regularly [29]. All tests were performed in a quiet room with the participants sitting in a comfortable chair with their feet resting on a small platform or briefcase. Stimuli were first applied either on the right or the left foot in a randomized and balanced order. To control for potential carry-over effects, the location of the delivered stimuli was alternated between the two feet after each measurement (supplementary Fig. S1). The participants were instructed to look away from the location where the stimuli were applied. In addition, participants were informed that only safe temperatures, with no associated risk of skin damage, would be applied and that the stimulations were aimed at eliciting cold, warm, and painful sensations, respectively. Importantly, the participants were naive with respect to the hypotheses of the study and received no information on the exact temperatures applied on the skin, the order of the stimulation temperatures, or the expected quality of their thermal sensations. During the tests, the participants did not receive any feedback on whether their reported quality matched the actual temperatures.
Deep band modulation, frequency discrimination, temporal resolution and audibility effects: phrase perception with and without hearing impairment among older adults
Published in Hearing, Balance and Communication, 2022
Hemanth Narayan Shetty, Suma Raju
A three-way [SLs (20 dB and 40 dB SLs)* frequencies (1 kHz and 6 kHz)* masking type (forward and backward)] repeated measure analysis of variance was conducted to compare the frequency discrimination between sensation levels in each frequency and making type from the older adults with and without hearing loss. The three-way analyses of variance yielded a significant interaction effect between SLs*frequencies* masking types in OAG with and without hearing loss [F (1, 18) = 22.14, p = .001] on the frequency discrimination. It indicated that a significantly lower mean frequency difference limen was found in 40 dB SL than 20 dB SL in each frequency presented in both backward and forward masking types. In addition, a main effect of SLs on FDL was noted in an older adult group with and without hearing loss [F (1, 18) = 586.12, p = .001]. A significant main effect for the frequency on mean frequency difference limen was noted in OAG with and without hearing loss [F (2, 36) = 114.17, p = .001], confirming a significant decrease in FDL at 1 kHz than 4 kHz. The main effect for the making type was also significant in OAG with and without hearing loss [F (1, 18) = 751.60, p = .001] on mean FDL, indicating that mean FDL was significantly lower in the forward masking condition than in the backward masking condition. In addition, the main effect of the group yielded a significant difference in OAG with and without hearing loss [F (1, 18) = 16.55, p = .001], indicated that the mean frequency difference limen was significantly lower in individuals with hearing loss than without hearing loss. Further, to assess the group in which the FDL has caused the difference between SLs in each frequency and masking type, a paired-samples t-test was conducted. The results revealed that in each group, the FDL was significantly lower in 40 dB SL than in 20 dB SL at each frequency presented in either the forward masking or backward masking paradigm (Table 4).