The scaling of human grip configurations.

The many degrees of freedom of the hand and arm afford the wide range and rich adaptability of human grip configurations in action. Several classification schemes of human grip configurations have been proposed, but none is based on scaling laws of physical biology, which are well established for other categorizations of fundamental physical activities such as locomotion. This study examined the preferred human grip configurations used to displace to a new location cubes that varied systematically in length (L), mass (M), and density (ML-3). The body-scaled equation K = log L + (log M)/h (where h refers to anthropometric measures of the hand) predicted the grip configurations used to displace objects. The findings suggest that information about the dynamic scaling relation is picked up visually and organizes the many degrees of freedom of the hand-arm complex in the coordination of prehensile grip configurations.     

Body-scaled transitions in human grip configurations

This article reports two experiments that were set up to examine the preferred human grip configuration used to displace cubes that varied in length (Lc), mass (Mc), and density (ML3). In particular, the authors sought to provide a more precise test of a dimensional relation between the object and the hand that had previously been shown to predict the grip configuration used to transport an object from one location to another. The experiments examined 2 grip transitions (from 3 digits to 4 digits and from 1 hand to 2 hands) within 2 sets of object conditions. In Experiment 1, cubes with a low density and a small increment in size (1 mm) were used, whereas in Experiment 2, cubes with 2 fixed sizes and small increments in mass were used. The results showed that the body-scaled equation K = logLc + (logMc/a + bMh + cLh), where Mh and Lh are the anthropometric measures of the hand mass and length and a, b, and c are empirical constants, is the body-scaled information that predicts the grip configurations used to displace objects.     

Coordination of grip configurations as a function of force output

In this investigation, the authors examined the coordination and control of force production by the digits of the hand as a function of criterion force level and grip configuration. Each adult participant (N = 6: 3 men and 3 women) was required to place the thumb and a finger (or fingers) upon load cells that were fixed to a grasping apparatus that was clamped to a table. In the task, participants had to match a criterion continuous constant total force level displayed on a computer screen. There were 10 trials at each grip configuration and criterion force level combination on each of 3 consecutive days. The results showed that (a) different grip configurations minimized error at each force level; (b) there was a specific digit pairing within a given grip configuration that produced the highest correlation of force output; (c) the correlation between the force output of digits generally increased at higher force levels; (d) error was reduced at each force level and grip configuration over the practice period; and (e) the organization of the force output of each digit varied as a function of digit, force level, grip configuration, and practice. The findings are consistent with the hypothesis that coordination of the digits in prehension is reflective of an adaptive, task-specific solution that is modified with practice.     

Multidimensional rotation and scaling of configurations to optimal agreement

An integrated method for rotating and rescaling a set of configurations to optimal agreement in subspaces of varying dimensionalities is developed. The approach relates existing orthogonal rotation techniques as special cases within a general framework based on a partition of variation which provides convenient measures of agreement. In addition to the well-known Procrustes and inner product optimality criteria, a criterion which maximizes the consensus among subspaces of the configurations is suggested. Since agreement of subspaces of the configurations can be examined and compared, rotation and rescaling is extended from a data transformation technique to an analytical method.     

Recognition of extraversion level based on handwriting and support vector machines

This study investigated whether it is possible to train a machine to discriminate levels of extraversion based on handwriting variables. Support vector machines (SVMs) were used as a learning algorithm. Handwriting of 883 people (404 men, 479 women) was examined. Extraversion was measured using the Polish version of the NEO-Five Factor Inventory. The handwriting samples were described by 48 variables. The support vector machines were separately trained and tested for each sex, using 10-fold cross-validation. Good recognition accuracy (around .7) was achieved for 10 handwriting variables, different for men and women. The results suggest the existence of a relationship between handwriting elements and extraversion.     

Comparing effects of the horizontal-vertical illusion on grip scaling and judgment: relative versus absolute, not perception versus action

The discovery that the prehension component of an open-loop, two-fingered reach is largely immune to certain salient pictorial illusions has been used to suggest that humans possess 2 distinct visual systems, 1 that subserves perceptual judgment and 1 that mediates visually controlled action. In this article, the authors present evidence that suggests that the critical distinction is not that of reaching and judgment but of relative and absolute perception. Experiment 1 extends the findings of S. Aglioti, J. F. X. DeSouza, and M. A. Goodale (1995) and suggests that the manual prehension component of open-loop reaching is affected by the horizontal-vertical illusion to a much smaller degree than perceptual size judgments. In Experiments 2 and 3, however, when perceptual size judgment is directed at a single element of the display, this difference vanishes. Experiment 4 demonstrates that grip scaling is strongly affected by the illusion when a single reach is scaled to both the horizontal and vertical components of a triangular figure.     

A note on the gross configurations of the human auditory cortex

Gross inspection of 30 human brains (60 hemispheres) from patients without hearing impairment revealed the following configurations of gyri: one on left and two on right (14 of 30); two on left and two on right (11 of 30); one on left and one on right (3 of 30); two on left and one on right (1 of 30); and two on left and three on right (1 of 30). The last group has since been extended to include all combinations other than the first four and the proportions of these combinations appear to persist in larger tallies. Thirteen of the 30 brains displayed double gyri on the left while 25 had double gyri on the right. Seventeen of the 30 brains possessed a single gyrus on the left and four specimens had a single gyrus on the right. In general, the left side has a tendency to fewer gyral markings. The average cortical surface area on the left is 1198 mm² compared to 1380 on the right.     

The effects of random error and subsampling of dimensions on recovery of configurations by non-metric multidimensional scaling

Similarity judgments of three-dimensional stimuli were simulated, with the hypothetical subject attending to only some dimensions of stimulus variation (i.e., subsampling) on each trial. Recovery of the stimulus configuration by non-metric multidimensional scaling was investigated as a function of subsampling, the amount of random error in the judgments, and the number of stimuli being scaled.It was found that: (1) dimensions to which the subject often attends were well recovered even when dimensions seldom attended to were not, and (2) measures of recovery based on interpoint distances were inadequate. Several previous Monte Carlo studies were evaluated in light of the results.This report is based on a thesis submitted in partial fulfillment of the degree of Master of Arts at the University of Illinois. The thesis is an outgrowth of earlier work presented in Cohen, H. S., Wing, P. L., & Jones, L. E. The effects of error and subsampling of dimensions on multidimensional scaling solutions. Mathematical Psychology Meetings, Princeton, September, 1971.     

Development of prehension between 5 and 10 years of age: distance scaling, grip aperture, and sight of the hand

The authors investigated whether 5- to 10-year-old children (N = 75) differ from adults (N = 12) in the developmental course of distance scaling and the adaptations to the inability to see the hand during prehension movements. The children reached under a surface and grasped and lifted an object suspended through it. All children scaled velocity appropriately for movement distance, both with and without sight of the hand. However, 5- to 6-year-old children did not increase grip aperture with increased distance, whereas older children and adults did. The older children and adults spent longer after peak deceleration when they could not see the hand, and maximum grip aperture (MGA) was larger, providing an increased safety margin. Children aged 5 to 6 spent the same amount of time between peak deceleration and grasp, whether or not they could see the hand, and they failed to increase MGA when they could not see the hand. Prehension in the younger children differed from that of older children in two ways: The younger children did not integrate reach and grasp over different distances and did not use visual information about hand position to optimize accuracy.     

When knowing the name of objects is not enough to categorize them

Two experiments explored 16-month-olds' learning of new nouns, and their use of these nouns to categorize objects. In both experiments, infants were presented with triads of perceptually dissimilar objects, which were given made-up names, two of the objects receiving the same name. Following each training phase, infants were tested on whether: (a) they could use the names to categorize the objects (Experiment 1), or (b) they had actually learned the association between the names and the objects (Experiment 2). Our results show that 16-month-olds can simultaneously learn the name of three objects, but cannot use these newly learned names to categorize the objects in the absence of any other cue to categorization. These results are discussed in light of different hypotheses regarding the way infants come to use names to categorize objects.     

In search and proof of human beings, not machines

My intentions are twofold in this autobiographical account. On one hand, I hope to present empirical and theoretical evidence for a freely willing human being. On the other, I carefully record the developing stages I lived through to cement my confidence in the image of humanity I would like my readers to accept. I have, in my career development, worked hard to redefine psychological terminology, defend traditional scientific practices, and provide support for all those colleagues who can no longer stand the mechanistic characterization that so many psychology departments insist on. I have spent over 40 years pursuing such goals. It is not likely that I will ever give up my quest for what I take to be a genuine humanity.     

Effect of tourniquet-induced ischemia on magnitude scaling of tactile stimuli applied to the human hand

The effect of tourniquet-induced ischemia was tested on magnitude scaling of supraliminal tactile stimuli (single-cycle sine waves) applied to the human hand contra- or ipsilaterally to the cuff. Magnitude estimations were not influenced on the contralateral side. In the ischemic hand there was a reduction of magnitude estimates beginning 12 min. after inflation of the cuff, independent of the stimulus intensity. The results indicate that peripheral noxious stimulation does not produce a nonsegmental reduction of tactile sensitivity. Moreover, it is suggested that the thickest afferent mechanoreceptive fibers (A-beta) have a major role in the mediation of tactile signals both at liminal and supraliminal levels.     

Support vector machine for classification of walking conditions of persons after stroke with dropped foot

Walking with dropped foot represents a major gait disorder, which is observed in hemiparetic persons after stroke. This study explores the use of support vector machine (SVMs) to classify different walking conditions for hemiparetic subjects. Seven participants with dropped foot (category 4 of functional ambulatory category) walked in five different conditions: level ground, stair ascent, stair descent, upslope, and downslope. The kinematic data were measured by two portable sensor units, each comprising an accelerometer and gyroscope attached to the lower limb on the shank and foot segments. The overall classification accuracy of stair ascent, stair descent, and other walking conditions was 92.9% using input features from the sensor attached to the shank. It was further improved to 97.5% by adding two more inputs from the sensor attached to the foot. Stair ascent was also classified by the inputs from the foot sensor unit with 96% accuracy. The performance of an SVM was shown to be superior to that of other machine learning methods using artificial neural networks (ANN) and radial basis function neural networks (RBF). The results suggested that the SVM classification method could be applied as a tool for pathological gait analysis, pattern recognition, control signals in functional electrical stimulation (FES) and rehabilitation robot, as well as activity monitoring during rehabilitation of daily activities.     

In the grip of the python: Conflicts at the university-industry interface

When the University of Toronto withdrew a contract it held with me in December 2000, it initiated a sequence of events that led to a public letter to the University from senior figures in the world psychopharmacology community protesting against the infringement of academic freedom involved and a first ever legal action, undertaked by this author, seeking redress for a violation of academic freedom. The issues of academic freedom surrounding this case have been intertwined with a debate about the possibility that the selective serotonin reuptake inhibitor (SSRI) group of antidepressants have the potential to trigger suicidality in a subgroup of patients. Whether the SSRIs do trigger suicidality or not, exploration of this issue has given rise to a number of worrying sets of observations. First, in my view, there is evidence that pharmaceutical companies have miscoded raw data on suicidal acts and suicidal ideation. Second, this author also maintains that there is a growing body of examples of ghostwriting of articles in the therapeutics domain. Many of the tensions evident in this case, therefore, can be linked to company abilities to keep clinical trial data out of the public domain — this is the point at which the pharmaceutical python gets a grip on academia.     

Non‐human Support: Broadening the Scope of Attachment Theory

Attachment theory proposes that people form strong social ties because certain relationships provide feelings of security and support. Traditionally, theorists and researchers have assumed that because this process is innate and evolved, only human targets are capable of meeting a person's needs for security. Recent research challenges this assumption by demonstrating that an array of targets, such as places and pets, can also satisfy needs for security, particularly under conditions of threatened or absent connection to other people. We bring together these diverse findings and discuss how they enrich our understanding of the nature and operation of attachment processes and related phenomena. Specifically, this line of research contributes to a comprehensive picture of the diverse means by which people flexibly seek and maintain psychological security both within and outside of their close, interpersonal relationships. It also raises new research questions concerning the similarities and differences between human and non‐human support.     

Extrapolating human judgments from skip-gram vector representations of word meaning

There is a growing body of research in psychology that attempts to extrapolate human lexical judgments from computational models of semantics. This research can be used to help develop comprehensive norm sets for experimental research, it has applications to large-scale statistical modelling of lexical access and has broad value within natural language processing and sentiment analysis. However, the value of extrapolated human judgments has recently been questioned within psychological research. Of primary concern is the fact that extrapolated judgments may not share the same pattern of statistical relationship with lexical and semantic variables as do actual human judgments; often the error component in extrapolated judgments is not psychologically inert, making such judgments problematic to use for psychological research. We present a new methodology for extrapolating human judgments that partially addresses prior concerns of validity. We use this methodology to extrapolate human judgments of valence, arousal, dominance, and concreteness for 78,286 words. We also provide resources for users to extrapolate these human judgments for three million English words and short phrases. Applications for large sets of extrapolated human judgments are demonstrated and discussed.     

Reminiscences in honor of Erik Erikson: Contributions to psychotherapeutic method and configurations of human potential

In this essay, I offer some reminiscences of Erik Erikson. While he is best known for his work on stages of development across the life span, I focus here on his lesser known, but significant contributions to the psychotherapeutic method with children, adolescents, and adults, respectively.     

Gleaning in the field of dual scaling

Some historical background and preliminary technical information are first presented, and then a number of hidden, but important, methodological aspects of dual scaling are illustrated and discussed: normed versus projected weights, the amount of information accounted for by each solution, a perfect solution to the problem of multidimensional unfolding, multidimensional quantification space, graphical display, number-of-option problems, option standardization versus item standardization, and asymmetry of symmetric (dual) scaling. Contrary to the common perception that dual scaling and similar quantification methods are now mathematically transparent, the present study demonstrates how much more needs to be clarified for routine use of the method to arrive at valid conclusions. Data analysis must be carried out in such a way that common sense, intuition and sound logic will prevail.Presidential Address delivered at the Annual Meeting of the Psychometric Society, Banff Centre for Conferences, Banff, Alberta, Canada, June 27–30, 1996. The work has been supported in part by a grant from the Natural Sciences and Engineering Research Council of Canada. I am grateful to Ira Nishisato for his comments, Ingram Olkin and Yoshio Takane for important references, and Liqun Xu for computational help.