New lower and upper bounds for communality in factor analysis

We derive several relationships between communalities and the eigenvalues for ap ×p correlation matrix under the usual factor analysis model. For suitable choices ofj, _j (), where _j () is thej-th largest eigenvalue of , provides either a lower or an upper bound to the communalities for some of the variables. We show that for at least one variable, 1 - _p () improves on the use of squared mulitiple correlation coefficient as a lower bound.This research was done while the second author was at Tokyo Institute of Technology.     

Application of the bootstrap methods in factor analysis

A Monte Carlo experiment is conducted to investigate the performance of the bootstrap methods in normal theory maximum likelihood factor analysis both when the distributional assumption is satisfied and unsatisfied. The parameters and their functions of interest include unrotated loadings, analytically rotated loadings, and unique variances. The results reveal that (a) bootstrap bias estimation performs sometimes poorly for factor loadings and nonstandardized unique variances; (b) bootstrap variance estimation performs well even when the distributional assumption is violated; (c) bootstrap confidence intervals based on the Studentized statistics are recommended; (d) if structural hypothesis about the population covariance matrix is taken into account then the bootstrap distribution of the normal theory likelihood ratio test statistic is close to the corresponding sampling distribution with slightly heavier right tail.This study was carried out in part under the ISM cooperative research program (91-ISM · CRP-85, 92-ISM · CRP-102). The authors would like to thank the editor and three reviewers for their helpful comments and suggestions which improved the quality of this paper considerably.     

How is motion disparity integrated with binocular disparity in depth perception?

Two experiments presented motion disparity conflicting with binocular disparity to examine how these cues determined apparent depth order (convex, concave) and depth magnitude. In each experiment, 8 subjects estimated the depth order and depth magnitude. The first experiment showed the following. (1) The visual system used one of these cues exclusively in selecting a depth order for each display. (2) The visual system integrated the depth magnitude information from these cues by a weighted additive fashion if it selected the binocular disparity in depth order perception and if the depth magnitude specified by motion disparity was small relative to that specified by binocular disparity. (3) The visual system ignored the depth magnitude information of binocular disparity if it selected the motion disparity in depth order perception. The second experiment showed that these three points were consistent whether the subject’s head movement or object movement generated motion disparity.     

Dependence of illusory motion on directional consistency in oblique components

Pinna and Brelstaff (2000 Vision Research 40 2091-2096) reported a motion illusion on viewing two concentric circles consisting of quadrangular components with black and white sides on a grey background. Our results suggest that the illusion is based on the integration of motion signals derived from oblique components, and on the consistency in the direction among those components. Furthermore, arrays of these oblique components can elicit the perception of motion not only for the oblique components themselves, but also for other objects in the picture. We propose that the motion illusion depends not only upon detection of the illusory motion signal at each local oblique component, but also upon the accumulation of the signal all over the stimulus configuration.     

Electrical properties and local structure of n-type conducting amorphous indium sulphide

An n-type amorphous chalcogenide, In₄₉S₅₁, having a band gap of 1.9eV, has been found. The conductivity in as-prepared films was ～10^?4?S?cm^?1, which increased to 1?×?10^?1?S?cm^?1 on post-annealing at 125°C in vacuum, accompanied by a reduction in the sulphur content of the films. TEM observations showed the amorphous nature of the films before and after annealing. Both Seebeck and Hall coefficients are negative, indicating that the major carriers are electrons. The Hall mobility can be as large as 26?cm²?V^?1?s^?1 at 300?K. No significant changes to the optical absorption were observed upon annealing. Analysis of the X-ray radial distribution function reveals that the sulphur atoms have four-fold coordination, making the structure more rigid than conventional amorphous chalcogenides in which the chalcogen is alloyed to elements of group IV or V of the periodic table. We tentatively associate the electron carrier generation with the formation of sulphur vacancies.     

Integration of motion parallax with binocular disparity specifying different surface shapes

We investigated the interaction between motion parallax and binocular disparity cues in the perception of surface shape and depth magnitude by the use of the random dot stimuli in which these cues specified sinusoidal depth surfaces undulating with different spatial frequencies. When ambiguous motion parallax is inconsistent with unambiguous disparity cue, the reasonable solution for the visual system is to convert the motion signal to the flow on the surface specified by disparity. Two experiments, however, found that the visual system did not always use this reasonable solution; observers often perceived the surface specified by a composite of the two cues, or the surface specified by parallax alone. In the perception of this composite of the two cues, the apparent depth magnitude increased with the increase of the depth magnitude specified by both cues. This indicates that the visual system can combine the depth magnitude information from parallax and disparity in an additive fashion. The interference with parallax by disparity implies that the parallax processing is not independent of the disparity processing.     

Feeling bad about screwing up: emotion regulation and action monitoring in the anterior cingulate cortex

This study examined neural features of emotional responses to errors. We specifically examined whether directed emotion regulation of negative emotion associated with error modulates action-monitoring functions of anterior cingulate cortex, including conflict monitoring, error processing, and error prevention. Seventeen healthy adults performed a continuous performance task during assessment by fMRI. In each block, participants were asked either to increase or decrease their negative emotional responses or to react naturally after error commission. Emotion regulation instructions were associated with modulation of rostral and dorsal anterior activity and of their effective connectivity following errors and conflict. Cingulate activity and connectivity predicted subsequent errors. These data may suggest that responses to errors are affected by emotion and that aspects of emotion and cognition are inextricably linked, even during a nominally cognitive task.     

Is lesion of Exner's area linked to progressive agraphia in amyotrophic lateral sclerosis with dementia? An autopsy case report

Agraphia, as a neuropsychological symptom of ALS, especially ALS with dementia (ALS-D), has recently attracted more attention. However, the brain lesion responsible has not been identified. Here we present an autopsy case of ALS-D of a patient with obvious agraphia, without aphasia, that also presented cerebrospinal degeneration with TDP-43-pathology compatible with ALS-D. Of the pre-motor frontal lobe cortices, degeneration and immuno-histochemical pathology were most obvious in the caudal area of the left middle frontal gyrus, or Exner's area. Assuring this area plays a pivotal role in the kanji and kana formation used in writing the Japanese language, this case of ALS-D showed both agraphia and Exner's area stressed pathological lesions. It may thus be the first case to indicate an intimate relationship between the neuropsychological symptoms and an associated lesion for ALS-D.     

Verbal and visual recall span curves between 1 ms and 1 min

Summary The recall spans for verbal and visual information were represented, respectively, in terms of the number of digits and the number of dots in a 5×5 matrix. They were measured independently by the method of limits as functions of presentation times which ranged from 1 ms to 64 s. The curves were very similar: each had two plateaus, one at 10 to 100 ms and one at 2 to 8 s presentation levels. These plateaus suggest two kinds of capacity limitation on information processing. The first limitation is concerned with the transfer of information from iconic memory to short-term memory (STM); the second indicates the saturation of the limited capacity short-term store. Short-term and long-term mechanisms are involved not only in verbal memory but also in visual memory, since the second plateau followed by an increasing portion appears in the visual span curve as well as in the verbal one. Finally, the distinction between verbal and visual STM is discussed, based on a) the selective interference effects of distracting tasks upon the retention of verbal and visual materials, and b) the weak correlation between verbal and visual spans.     

Changes in somatosensory evoked potentials and Hoffmann reflexes during fast isometric contraction of foot plantarflexor in humans

In the present study, the extent to which the early component of somatosensory evoked potentials (SEPs) and the Hoffmann (H-) reflex induced by stimulation of the posterior tibial nerve are altered during the ascending and descending phases of fast plantarflexion was investigated. SEPSs and H-reflex of the soleus following tibial nerve stimulation were examined during fast plantarfiexion when performed by nine normal subjects. The analyses focused on differences in amplitude modulation of the P30-P40 component of SEP and the H-reflex between the ascending and descending phases of full-wave rectified and averaged soleus electromyographic (EMG) activity. The H-reflex amplitude was significantly increased and decreased during the ascending and descending phases more than under resting control conditions, respectively. The reduction of SEP amplitude was 49% for the ascending phase and 83% for the descending phases with respect to the resting situation. Modulation of SEP during the ascending and descending phases was robustly retained even during ischemic nerve blockade of large diameter afferent fibers. These findings suggest that the transmission of afferent inputs from muscle spindles to motoneurons and to the somatosensory cortex during fast isometric contraction of the plantar flexor is regulated in a time-dependent fashion by descending commands.