Human sensitivity to gearshift loads

This paper describes an investigation of the ability of humans to distinguish different levels of gearlever load. A test rig with a forward-backward moving gearshift lever was constructed using the typical interior dimensions of European B segment automobiles. The rig used a system of weights and pulleys to provide a load which could be varied in steps of 1%. Four reference loads were chosen which were considered representative of automotive gearshift operation: 0.5, 1.0, 2.0 and 5.0 kg. Twenty subjects took part in the study. Using a variation on the psychophysical method of limits, the subjects were asked to respond whether a test load was heavier or lighter than a reference load. The Weber Fraction was found to decrease monotonically from a value of 0.036 for the 0.5 kg reference load to a value of 0.029 at the 5.0 kg reference load. The average value across all reference loads was 0.032. Measurements of the gearshift force made by means of a knob containing a load cell suggested that the variation in the measured Weber Fraction might be attributable to the time behaviour of the force exchanged between the human subject and the control surface

Sinuosity and the affect grid: A method for adjusting repeated mood scores

Copyright @ 2012 Ammons Scientific. The article can be accessed from the links below.This article has been made available through the Brunel Open Access Publishing Fund.Sinuosity is a measure of how much a travelled pathway deviates from a straight line. In this paper, sinuosity is applied to the measurement of mood. The Affect Grid is a mood scale that requires participants to place a mark on a 9 x 9 grid to indicate their current mood. The grid has two dimensions: pleasure-displeasure (horizontal) and arousal-sleepiness (vertical). In studies where repeated measurements are required, some participants may exaggerate their mood shifts due to faulty interpretation of the scale or a feeling of social obligation to the experimenter. A new equation is proposed, based on the sinuosity measure in hydrology, a measure of the meandering of rivers. The equation takes into account an individual's presumed tendency to exaggerate and meander to correct the score and reduce outliers. The usefulness of the equation is demonstrated by applying it to Affect Grid data from another study.This article is made available through the Brunel Open Access Publishing Fund

The Underestimation Of Egocentric Distance: Evidence From Frontal Matching Tasks

There is controversy over the existence, nature, and cause of error in egocentric distance judgments. One proposal is that the systematic biases often found in explicit judgments of egocentric distance along the ground may be related to recently observed biases in the perceived declination of gaze (Durgin & Li, Attention, Perception, & Psychophysics, in press), To measure perceived egocentric distance nonverbally, observers in a field were asked to position themselves so that their distance from one of two experimenters was equal to the frontal distance between the experimenters. Observers placed themselves too far away, consistent with egocentric distance underestimation. A similar experiment was conducted with vertical frontal extents. Both experiments were replicated in panoramic virtual reality. Perceived egocentric distance was quantitatively consistent with angular bias in perceived gaze declination (1.5 gain). Finally, an exocentric distance-matching task was contrasted with a variant of the egocentric matching task. The egocentric matching data approximate a constant compression of perceived egocentric distance with a power function exponent of nearly 1; exocentric matches had an exponent of about 0.67. The divergent pattern between egocentric and exocentric matches suggests that they depend on different visual cues

Touching Curvature and Feeling Size: A Contrast Illusion

Plaisier M, Ernst MO. Touching Curvature and Feeling Size: A Contrast Illusion. Multisensory Research. 2013;26(5):457-463.We know that our eyes can be deceiving. Here we demonstrate that we should not always trust our sense of touch either. Previous studies have shown that when pinching an object between thumb and index finger, we can under many circumstances accurately perceive its size. In contrast, the current results show that the local curvature at the areas of contact between the object and the fingers causes systematic under- or overestimation of the object’s size. This is rather surprising given that local curvature is not directly related to the object’s size. We suggest an explanation in terms of a contrast between the finger separation and an inferred relationship between local curvature and size. This study provides the first demonstration of an illusory haptic size percept caused by local curvature in a pinch grip

Reducing bias in auditory duration reproduction by integrating the reproduced signal

Duration estimation is known to be far from veridical and to differ for sensory estimates and motor reproduction. To investigate how these differential estimates are integrated for estimating or reproducing a duration and to examine sensorimotor biases in duration comparison and reproduction tasks, we compared estimation biases and variances among three different duration estimation tasks: perceptual comparison, motor reproduction, and auditory reproduction (i.e. a combined perceptual-motor task). We found consistent overestimation in both motor and perceptual-motor auditory reproduction tasks, and the least overestimation in the comparison task. More interestingly, compared to pure motor reproduction, the overestimation bias was reduced in the auditory reproduction task, due to the additional reproduced auditory signal. We further manipulated the signal-to-noise ratio (SNR) in the feedback/comparison tones to examine the changes in estimation biases and variances. Considering perceptual and motor biases as two independent components, we applied the reliability-based model, which successfully predicted the biases in auditory reproduction. Our findings thus provide behavioral evidence of how the brain combines motor and perceptual information together to reduce duration estimation biases and improve estimation reliability

Accurate Visuomotor Control below the Perceptual Threshold of Size Discrimination

Background: Human resolution for object size is typically determined by psychophysical methods that are based on conscious perception. In contrast, grasping of the same objects might be less conscious. It is suggested that grasping is mediated by mechanisms other than those mediating conscious perception. In this study, we compared the visual resolution for object size of the visuomotor and the perceptual system. Methodology/Principal Findings: In Experiment 1, participants discriminated the size of pairs of objects once through perceptual judgments and once by grasping movements toward the objects. Notably, the actual size differences were set below the Just Noticeable Difference (JND). We found that grasping trajectories reflected the actual size differences between the objects regardless of the JND. This pattern was observed even in trials in which the perceptual judgments were erroneous. The results of an additional control experiment showed that these findings were not confounded by task demands. Participants were not aware, therefore, that their size discrimination via grasp was veridical. Conclusions/Significance: We conclude that human resolution is not fully tapped by perceptually determined thresholds

Care planning: a neoliberal three card trick

Introduction The three card game, sometimes called find the queen, is a classic confidence trick, typically taking place on an impromptu table top, set up on pavement or street corner. The tricksters usually operate in teams, pulling in punters and ‘losing’ games with their fellows to persuade prospective speculators the game is winnable. For our titular purposes the three card trick serves as a metaphor for broader deceits. We are concerned with how well-meaning mental health nurses can enter into a set of apparently rational practices, insisted upon by policy and protocol, seemingly motivated by ideals of care and protection from harm, yet functioning to destroy the very essence of what it might mean to be a caring, progressive practitioner by contributing to a mutuality of alienation that, at the relational level, is the opposite of what services intend to achieve. This may prove to be the case because an external confidence trickster (neoliberalism) is actually in charge, and the real function of the game serves other ends. The whole point of the game is that genuine players can never win, and for the trickster to triumph it is necessary that these punters are willing, gullible and in most circumstances accept losses without too much fuss. When the losers do not go quietly this is referred to in the argot of the con as ‘squawking’, and personnel are deployed on the periphery to ensure any squawk is minimised. Various strategies can be used to ‘cool out the mark’, and are analogous to the means by which people are assisted to adjust to life’s disappointments in other contexts, including encounters with priests or sundry psy-professionals (Goffman 1952; McKeown et al. 2013). This commentary paper seeks to provoke nursing out of its state of gullibility and self-deception even if this involves painful reflection on the losses inherent in our collective game of mental health care. If we are to defend the importance of mental health nursing we must think more critically about our complicity within oppressive systems of control and do something about it. There is a lengthy critical tradition to draw on. We urge mental health nurses to squawk, asserting a more recalcitrant and rebellious standpoint, preferably in alliance with service users, refusers and survivors. Acknowledging the constraints upon nursing’s agency, deficits of power, and structural disadvantage need not default to impotence and inaction: collective resistance is always possible, however difficult the circumstances

Evaluating a model of global psychophysical judgments for brightness: II. Behavioral properties linking summations and productions

Steingrimsson (Attention, Perception, & Psychophysics, 71, 1916–1930, 2009) outlined Luce’s (Psychological Review, 109, 520–532 2002, 111, 446–454 2004) proposed psychophysical theory and tested, for brightness, behavioral properties that, separately, gave rise to two psychophysical functions, Ψ⊕ and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\Psi_{{ \circ_p}}}$$\end{document}. The function Ψ⊕ maps pairs of physical intensities onto positive real numbers and represents subjective summation, and the function \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\Psi_{{ \circ_p}}}$$\end{document} represents a form of ratio production. This article, the second in a series expected to consist of three articles, tests the properties linking summation and production such that it forces \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\Psi_{{ \circ_p}}} = {\Psi_\oplus } = \Psi$$\end{document}. The properties tested are a form of distributivity and, in three experiments, were subjected to an empirical evaluation. Considerable support is provided for the existence of a single function Ψ for both summation and ratio production. The scope of this series of articles is to establish the theory as a descriptive model of binocular brightness perception