The phenomenon of the tip of the tongue in aging

This paper presents new data on the tip of the tongue (TOT) phenomenon and its resolution in aging. 140 volunteers ranging from 19 to 82 years participated in an experiment using definitions about common names, proper names, adjectives and verbs to elicit TOTs. We studied the resolution of the TOTs introducing a free word-recall task and a priming task. Older adults experienced more TOTs than younger adults regardless of the level of vocabulary. Phonological priming, and not free recall of words, improved resolution for the older adults. The results are discussed in relation to the theory of the transmission deficit.     

Effect of alcohol on visual constancy values and possible relation to driving performance

The effects of the constancy phenomena in vision seem to be to provide information about the environment which is not solely dependent upon the characteristics of shape or size of the retinal image but which is modified by the brain to appear closer to the idealized characteristics of the real object. There is a regression away from the retinal image towards the actual object's characteristics. A plate viewed from an angle tends to look more like a disc than would be predicted from the geometry of perspective. This ability of the brain to impose conditions on perception is a high-level process which may be adversely affected by the depressive action of alcohol on the nervous system. In this case, objects such as road signs, etc. would tend to look smaller and so more distant than when sober if regression is inhibited. Drivers' reactions may be delayed if hazards are seen smaller and further away, thereby increasing the possibility of accident. This research indicates a reduction in phenomenal regression after ingestion of alcohol. There are implications for accident-rates in driving or in industry.     

The influence of object size and surface shape on shape constancy from stereo

The failure of shape constancy from stereoscopic information is widely reported in the literature. In this study we investigate how shape constancy is influenced by the size of the object and by the shape of the object's surface. Participants performed a shape-judgment task on objects of five sizes with three different surface shapes. The shapes used were: a frontoparallel rectangle, a triangular ridge surface, and a cylindrical surface, all of which contained the same maximum depth information, but different variations in depth across the surface. The results showed that, generally, small objects appear stretched and large objects appear squashed along the depth dimension. We also found a larger variance in shape judgments for rectangular stimuli than for cylindrical and ridge-shaped stimuli, suggesting that, when performing shape judgments with cylindrical and ridge-shaped stimuli, observers rely on a higher-order shape representation.     

Development of size constancy in children: a test of the proximal mode sensitivity hypothesis

In two experiments, we attempted to replicate Shallo and Rock's (1988) finding that 5- and 6-year-old children exhibit size constancy for a distant object when tested with comparison objects that are matched for visual angle. Experiment 1 (N = 80) included four age groups: 5-, 6-, and 9-year-olds and adults. Participants viewed one standard object from 61 m and indicated which of nine nearby comparison objects matched the standard object in size. The comparison objects subtended equal visual angles in one condition and different visual angles in another. In both conditions, the 5- and 6-year-old children underestimated the size of the standard object, whereas the 9-year-old children and adults made nearly accurate size estimates. In Experiment 2 (N = 32), we replicated the finding that 6-year-old children underestimate size when tested with comparison objects that subtend equal visual angles. Our results conflict with those of Shallo and Rock and support earlier findings that young children do not exhibit size constancy for distant objects.     

The interaction of oculomotor cues and stimulus size in stereoscopic death constancy.

In the natural world, observers perceive an object to have a relatively fixed size and depth over a wide range of distances. Retinal image size and binocular disparity are to some extent scaled with distance to give observers a measure of size constancy. The angle of convergence of the two eyes and their accommodative states are one source of scaling information, but even at close range this must be supplemented by other cues. We have investigated how angular size and oculomotor state interact in the perception of size and depth at different distances. Computer-generated images of planar and stereoscopically simulated 3-D surfaces covered with an irregular blobby texture were viewed on a computer monitor. The monitor rested on a movable sled running on rails within a darkened tunnel. An observer looking into the tunnel could see nothing but the simulated surface so that oculomotor signals provided the major potential cues to the distance of the image. Observers estimated the height of the surface, their distance from it, or the stereoscopically simulated depth within it over viewing distances which ranged from 45 cm to 130 cm. The angular width of the images lay between 2 deg and 10 deg. Estimates of the magnitude of a constant simulated depth dropped with increasing viewing distance when surfaces were of constant angular size. But with surfaces of constant physical size, estimates were more nearly independent of viewing distance. At any one distance, depths appeared to be greater, the smaller the angular size of the image. With most observers, the influence of angular size on perceived depth grew with increasing viewing distance. These findings suggest that there are two components to scaling. One is independent of angular size and related to viewing distance. The second component is related to angular size, and the weighting accorded to it grows with viewing distance. Control experiments indicate that in the tunnel, oculomotor state provides the principal cue to viewing distance. Thus, the contribution of oculomotor signals to depth scaling is gradually supplanted by other cues as viewing distance grows. Binocular estimates of the heights and distances of planar surfaces of different sizes revealed that angular size and viewing distance interact in a similar way to determine perceived size and perceived distance.     

On the relation of adaptation to field displacement during head movements to the constancy of visual direction

When the normal constancy process on which the apparent immobility of the visualfield during head movements is based was strengthened by the same method that produces adaptation to abnormal conditions in the constancy of visual direction, and when this training of the normal constancy process immediately preceded experimental adaptation, the effectiveness of the latter was diminished. This result applied not only to adaptation to horizontal field displacement and to vertical field displacement during turning of the head, but also to vertical field displacement during nodding of the head, a condition to which adaptation was here demonstrated for the first time.     

Strengths and distress in adults who are aging with HIV: a pilot study

In this qualitative pilot study, distress and strengths associated with aging with Human Immunodeficiency Virus (HIV) were identified for 12 participants. Potential sources of distress were fear of death, financial worries, fear of disclosure, stigma, and long-term coping. Strengths were hardiness, renewed spirituality, social support, community service, and openness to aging. Ways of mitigating these barriers and accentuating these strengths can be explored by mental health professionals if extended with a representative larger sample.     

The relation between risk perceptions and physical activity among older adults: a prospective study

Past studies have found that risk perceptions of suffering from diseases play an important role in the development of intentions to perform physical activity (PA). According to the behaviour motivation hypothesis, perceived risk could be positively and directly related to PA, but this possibility has been ignored and/or underestimated. Accounting for recent methodological developments on the importance of study design and risk perception assessment, the purpose of the present study was to examine the risk-perceptions-PA relationship among older adults. Participants (N=143) aged from 61 to 70 years initially underwent measurement of risk perceptions, baseline PA, socio-demographic and health factors. Six months later, they were asked about their PA participation. Multiple regression analyses revealed that perceived risk of suffering from diseases and conditions without regular PA participation was an independent positive predictor of later PA, over and beyond baseline behaviour, socio-demographic and health variables. This study fills a gap in the existing literature on the PAs of older adults and reveals that risk perceptions are directly linked to their participation. In addition, it extends existing knowledge in health psychology on the behaviour motivation hypothesis, and emphasises the necessity of methodological adjustments when assessing the risk-perception-behaviour relationship.     

Fixed set in the perception of size in relation to lightness

When control subjects compared the sizes of two circles of different lightness, the lightness-size illusion was observed, i.e., the darker circle was perceived to be smaller. However, after experimental subjects were shown a large, light circle and a smaller, darker circle repeatedly, the subjective size of the dark circle increased. It decreased after repeated exposures to a small, light circle and a large, dark one. These changes in perception were assumed to be contrast effects produced by an experimentally fixed set and were similar to changes observed when the same method was previously applied by this author to the size-weight illusion. Despite differences in modality and dimension of perception, every application of the fixed-set method resulted in analogous patterns. When the situation of the set-fixing experiment and that of the critical experiment were similar to each other, the fixed set was activated more and greater contrast effects were produced.     

The effect of aging on termination of voluntary movement while standing: A study on community-dwelling older adults

For older adults, falls often occur when transitioning from motion to a complete stop, as the motor control required during this phase is very complex and challenging. The purpose of this study was to clarify the effect of aging on the motor control required to terminate motion. Twenty-five healthy older adults (aged >65 years) and 25 healthy young adults (20–23 years) performed a rapid stopping task while standing on a force plate. The rapid stopping task was conducted by analyzing center of pressure (COP) on the force plate during a visually guided tracking experiment. To assess the ability to terminate motion, we measured the velocity waveform for the COP, along with the reaction, propulsion, braking, and total movement times. Both the reaction and movement times of the older-adult group were significantly longer than those of the younger-adult group (all, p < 0.05). There was no significant difference between the groups in regard to the initial backward propulsion time; however, in the subsequent sequence of backward braking, forward propulsion, and backward braking, all times were longer in the older-adult group than in the younger-adult group (p < 0.05). Our results show that the series of time delays shown by older adults when initiating and terminating motion is due to not only delayed reactions but also delayed stopping. Furthermore, our findings suggest that older adults have not only a diminished propulsion ability but also a diminished braking ability.