Volitional lifestyle in healthy elderly: its relevance to rest-activity cycle,nocturnal sleep,and daytime napping

Sleep-related problems are prevalent among the aged. The present study examined the influence of a mentally active or "volitional" lifestyle on the rest-activity cycle, nocturnal sleep, and daytime napping in the healthy elderly. 14 aged individuals with a high Volitional lifestyle (M = 74.1 yr. old) and 14 with a Low Volitional lifestyle (M = 73.0 yr. old) were screened by questionnaires including the Philadelphia Geriatric Center Morale scale and the Self-confidence scale. Their activity levels were monitored by a wrist actigraph system for 14 consecutive days. They were also asked to record daily sleep logs. The total times of nocturnal sleep and daytime napping did not differ between the groups. However, the acrophases of circadian (tau = 24 hr.) and circasemidian (tau = 12 hr.) activity cycles were more advanced in the Low Volitional group. In addition, the High Volitional group took a daytime nap with a better timing than did the Low Volitional group: the former started a nap during the phase in which their activity level was going down, whereas the latter when their activity level was going up. These results suggest that high volitional lifestyle may be related to better rest-activity cycle in the healthy elderly.     

Motion parallax driven by head movements: conditions for visual stability, perceived depth, and perceived concomitant motion

Yoking the movement of the stimulus on the screen to the movement of the head, we examined visual stability and depth perception as a function of head-movement velocity and parallax. In experiment 1, for different head velocities, observers adjusted the parallax to find (a) the depth threshold and (b) the concomitant-motion threshold. Between these thresholds, depth was seen with no perceived motion. In experiment 2, for different head velocities, observers adjusted the parallax to produce the same perceived depth. A slower head movement required a greater parallax to produce the same perceived depth as faster head movements. In experiment 3, observers reported the perceived depth for different parallax magnitudes. Perceived depth covaried with smaller parallax without motion perception, but began to decrease with larger parallax and concomitant motion was seen. Only motion was seen with the larger parallax.     

From dichoptic to dichotic: historical contrasts between binocular vision and binaural hearing

Phenomena involving vision with two eyes have been commented upon for several thousand years whereas those concerned with hearing with two ears have a much more recent history. Studies of binocular vision and binaural hearing are contrasted with respect to the singleness of the percept, experimental manipulations of dichoptic and dichotic stimuli, eye and ear dominance, spatial localisation, and the instruments used to stimulate the paired organs. One of the principal phenomena that led to studies of dichotic hearing was dichoptic colour mixing. There was similar disagreement regarding whether colours or sounds could be combined when presented to different paired organs. Direction and distance in visual localisation were analysed before those for auditory localisation, partly due to difficulties in controlling the stimuli. Instruments for investigating binocular vision, like the stereoscope and pseudoscope, were invented before those for binaural hearing, like the stethophone and pseudophone.     

Perception of large change in distribution of heel pressure during backward leaning

We investigated the perception of the large change in distribution of heel pressure during backward leaning. Subjects were 12 healthy adults who reported perceiving a large change in distribution of heel pressure by a handheld switch while leaning voluntarily backward on a sole pressure analyzer and on a heel force plate. The large change was indicated at the center of heel pressure. Morphological features of the foot were measured on an X-ray film. The position of heel pressure center and the morphological locations were represented as relative distance (%) from the hindmost point of the heel, where foot length represented 100%. Center of heel pressure changed largely during backward leaning, and the position at which large change occurred was the same as that of the peak of the distribution. Large change in distribution of heel pressure was perceived at a position 1.3% posterior from that at which the large change actually occurred. The correlation between perceived and actual positions was significant (r = .91). Significant correlations were found between position of a large change of center and locations of heel pressure of both the lateral process of the calcaneal tuberosity and the top of the talar trochlea (r = .86; r = .71, respectively). The results indicate that subjects accurately perceive large changes in distribution of heel pressure and that the morphological features of the foot contribute to these changes.     

Bilateral lesions of the insular cortex or of the prefrontal cortex block the association between taste and odor in the rat

The neural basis for the association between taste and odor was investigated in the rat. First, behavioral procedures to study the mechanisms underlying the association between qualitative aspects of the odor and taste in rats were developed. Rats were presented with several pairings of the 0.3 mol/L NaCl solution and a flavor, and pairings of distilled water and another flavor. Then the rats received an IP injection of a furosemide to develop sodium deficiency. On the next day, the rats were presented with either of two types of odor-flavored water: water in which the flavor had been paired with NaCl, or water in which the flavor (grape or coffee) had been paired with distilled water. Normal rats avoided ingesting the water flavored with the odor previously paired with NaCl. Sodium-deprived rats, however, ingested the water flavored with that odor. Rats with lesions in either the insular cortex or in the prefrontal cortex neither preferred nor avoided the water flavored with the odor paired with NaCl. It was concluded that rats acquire association between taste and odor, and that the insular and the prefrontal cortices of the rats were involved in this association.     

Leonardo's constraint: two opaque objects cannot be seen in the same direction

Given Leonardo's constraint that 2 opaque objects cannot be seen in the same direction, how are the regions of objects occluded to 1 eye included in perception? To answer this question, the authors presented 3-dimensional stimuli, similar to the ones that concerned Leonardo, and measured the visual directions of their monocular and binocular regions. When the distance between near and far objects was large, the nonfixated object was seen as double and blurry. Leonardo's constraint was met by seeing the near object as double and transparent or the distant object as double and superimposed. When the distance between near and far objects was small, the constraint was met by a perceptual displacement and compression of parts of the nonfixated object.     

Perceived standing position after reduction of foot-pressure sensation by cooling the sole

We investigated the influence of the reduction of foot-pressure sensation by cooling the sole of the foot, at 1 degree C for 30 or 40 minutes, on the perception of standing position varied in the anteroposterior direction. The subjects were 16 healthy undergraduates. Firstly, for 4 of the subjects, cooling the sole of the foot decreased sensory information from the mechanoreceptors in the sole, by testing for an increase in the threshold for two-point discrepancy discrimination on the sole of the foot and for the disappearance of postural change with vibration to the sole. Next, the perception of standing position was measured by reproduction of a given standing reference position involving forward or backward leaning under both normal and cooled conditions of the feet. Standing position was varied in relation to the location of the center of foot pressure, defined as distance from the heel in percentage of the length of the foot. The reference positions, representing various locations of the center of foot pressure, were set at 10% increments from 20% to 80% of the length of the foot. With eyes closed, the subject first experienced the reference position and then attempted to reproduce it. The mean location of the center of foot pressure in the quiet standing posture was 45.7%. At the 40%, 50%, and 60% reference positions, those closest to quiet standing, absolute errors of reproduction were significantly larger than at other reference positions in both the normal and the cooled conditions. They were significantly larger in the cooled than in the normal condition. The 50% and 60% reference positions were reproduced significantly further forward in the cooled than in the normal condition. These results may be explained as due to an absence of marked changes in sensory information from both muscular activity and foot pressure when moving to reference positions close to the quiet standing posture.     

Effect of repetition on grammaticality judgments under objective and subjective self-awareness conditions

Three experiments were performed to investigate the differential effect of repeated presentation of sentences on judgments of grammaticality under the two mental states of objective and subjective self-awareness. In Experiment 1, 22 students judged the relative grammaticality of sentences twice, receiving a repetition treatment between the two judgments. During the repetition phase, they were exposed to a repeated presentation of sentences. The findings showed that repetition makes a judgment criterion more stringent on judgments after repetition than on those before repetition for the subjectively self-aware subjects, while it does not influence the judgments for the objectively self-aware subjects. Experiment 2 was run using a revised procedure with 26 students. The findings showed the expected, interaction, such that the repetition makes a criterion stringent for the subjectively self-aware subjects while it makes the criterion lenient for the objectively self-aware subjects. Experiment 3 examined with 12 students whether the finding for the latter subjects could be explained, by divided attention theory in a concurrent task condition. The findings showed no change of judgment criterion. These findings indicate that repeated exposure to the sentences exerts differential effects on grammaticality judgments dependent on whether the subjects are objectively or subjectively self-aware.     

The relativity of linguistic intuition: The effect of repetition on grammaticality judgments

Three experiments were performed to show the relativity of linguistic intuition in grammaticality judgments. In Experiment 1, 12 students judged the relative grammaticality of isolated sentences twice, receiving a repetition treatment between the two judgments. During the repetition phase, they were exposed to a repeated presentation of sentences. The findings show that the repetition treatment makes a judgment criterion more stringent for both grammatical and ungrammatical sentences. In Experiment 2, a release-from-the-proactive-inhibition paradigm was used. Twelve students first judged the grammaticality of the isolated sentences, then received the repetition treatment, and finally, made a second judgment for the sentences embedded in context. No change in judgment criterion was found for the second judgment. Judgments of the ungrammatical sentences, when embedded in context, were found to be more lenient. In Experiment 3, 12 students judged sentences embedded in context. No change in judgment criterion was found. These findings are interpreted as suggesting that linguistic intuitions as revealed in grammaticality judgments are not absolute but relative in that they are easily influenced by repetition and other variables, such as embedded context.     

On-line and off-line reflexive resolution in Japanese logophoric sentences

This study investigates on-line and off-line resolution of a Japanese reflexive,jibun, for logophoric sentences, i.e., complex sentences involving a matrix verb that reflects one's point of view feelings, or state of consciousness, and for nonlogophoric sentences, i.e., complex sentences involving a subordinate adverbial clause. According to Kuroda's (1973) thesis and Chomsky's (1981) binding principle (for nonlogophoric sentences only), the reflexive in the logophoric sentences can be associated with the subject of both a matrix sentence and a subordinate sentence whereas that in the nonlogophoric sentences can only be associated with the subject of the subordinate sentence. In Experiment 1, 42 students were administered a probe-recognition task in which a probe was given for the subject either of the matrix sentence or of the subordinate sentence immediately after the end of the subordinate clause or at the end of a sentence following the matrix verb. Recognition times were faster for a matrix-subject probe than for a subordinatesubject probe regardless of the sentence type and probe position. In Experiment 2, 40 students were administered an on-line antecedent identification task in which they were required to quickly and accurately identify, when given a probe, the antecedent of the reflexive, with the probe given after the reflexive or at the end of a sentence. Regardless of the sentence type, matrix-subject was judged to be the antecedent of the reflexive more often than subordinate-subject, with the effect of probe position being negligible. An offline study required 136 students to indicate the antecedent(s) for the two types of sentence given in their entirety. No effect of sentence type was found. Findings indicate that neither Kuroda's thesis nor Chomsky's binding principle is applied when Japanese speakers parse logophoric and nonlogophoric sentences.Part of this study was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, No. 05610067. Deep gratitude is due to Professor D. D. Steinberg for reading an earlier version of this paper. Thanks are also due to Ms. S. Ogawa for her help in collecting part of the off-line data.