Fourier components of moving gratings

In designing experiments in which the proximal stimulus is a moving grating (including cases in which the distal stimulus is stationary but eye movements play a significant role), one must consider the effects of the motion of the stimulus on its Fourier components in the spatiotemporal frequency domain. Some of these effects are unexpected and counterintuitive. For example, the Fourier components of a moving grating do not include its stationary (or “instantaneous”) spatial frequency. Thus there is no linear filter that can extract a stationary grating from a moving one. Several useful relations are given for analyzing such stimuli.     

BEHAVIORAL ASSESSMENT FOR PEDIATRIC INTENSIVE CARE UNITS1

Two studies were conducted to analyze behaviors of staff and patients on a Pediatric Intensive Care Unit (PICU). In the first study, behavioral observation procedures were employed to assess patient state, physical position, affect, verbal behaviors, visual attention and activity engagement, and staff verbal behavior. On the average, one-third of the patients were judged to be conscious and alert but markedly nonengaged with their environment. In the second study, a member of the hospital staff provided alert patients with individual activities to determine whether a simple environmental manipulation could positively affect behavior of children in intensive care. Employing a reversal design, the activity intervention was found to increase attention and engagement and positive affect, and to decrease inappropriate behavior. Both studies demonstrate that behavioral assessment procedures can provide an empirical basis for designing PICU routines affecting children's psychosocial status, and, thus, complement current procedures designed to provide quality medical care.     

Menstrual cycle affects kinesthetic aftereffect, an index of personality and perceptual style

Research suggests that kinesthetic aftereffect (KAE) scores reflect status on a postulated stimulus intensity modulation (SIM) mechanism that damps down subjective stimulus intensity for some (reducing) and increases it for others (augmenting). Such a mechanism would help account for empirically observed individual differences in such behaviors as pain tolerance, sensory deprivation reactivity, and stimulation seeking. It was hypothesized and confirmed in three adult female samples that KAE varies curvilinearly over the menstrual cycle: Greater KAE reduction occurs at the cycle's beginning and end. Neither tiredness, oral contraception, medication, attention, nor social expectations can explain this finding. Of the behaviors studied in the KAE literature, only five are also encompassed by the menstrual cycle literature. Four of these (antisocial behavior, acute schizophrenic episodes, accidents, and activity level) show similar curvilinearity over the cycle. We hypothesize that cyclical variation in the SIM mechanism mediates the curvilinear pattern observed for both these four behaviors and KAE.     

Free recall of abstract and concrete words by American and Ghanaian college students

This investigation compared the free recall of concrete and abstract words in American and Ghanaian college students. There were no differences in the total number of words recalled as a function of concreteness or culture. However, recall of concrete words showed a greater improvement across trials for both cultures. Although there was no difference in the amounts of subjective organization exhibited by Ghanaian and American students, there was evidence for a greater serializing tendency among American students. It appears that the major cultural differences typically observed in African-American comparisons of free recall may be overshadowed by increases in the educational level of the subjects.     

The relationship between auditory recall and dysfluency in young stutterers

This study examined the relationship between auditory recall and dysfluent behavior in children. Subjects were 11 stutterers and 11 nonstutterers, ages 4.9–11.10. The Auditory Sequential Memory subtest of the ITPA and the Auditory Attention Span for Related Syllables subtest of the Detroit Test of Learning Aptitudes were administered to both groups. Results indicated that scores on the ITPA were not significantly different. Comparison of the group's scores on the DTLA were highly significant with the control group's scoring 35 months higher. After 6 months of therapy, six children in the experimental group were fluent. Posttests revealed no significant differences on the ITPA. On the DTLA, the experimental group's mean scores significantly increased by 13.9 months. The gain in auditory recall of meaningful material substantiated the hypothesized relationship between auditory recall and dysfluency. This relationship was not viewed as causative of stuttering; data were interpreted as evidence that increased fluency allows children to use previously suppressed linguistic data.     

Texture gradient effectiveness in the perception of surface slant

To assess the development of monocular slant perception as well as the relative effectiveness of different sources of information, children in first, third, and fifth grades and college adults were asked to make judgments of surface slant on the basis of monocular texture gradient information. Accuracy of judgment increased with increasing age. In addition, differences in gradient effectiveness were found. Compression gradients were relatively ineffective sources of information, whereas perspective and multiple gradients resulted in greater accuracy. The results suggest limitations on the specificity of certain forms of gradients.     

Distance perception under binocular and monocular viewing conditions

First, third, and fifth graders and college adults made judgments of absolute distance in a binocular (full-information) condition and in one of three monocular conditions: redundant texture gradient, compression gradient, and control (no texture). No age-related differences in accuracy of judgment were observed in any of the conditions. Substantial differences in the effectiveness of different kinds of information were found, however. The results indicate that the ability to register information for distance is well developed by first grade, but that substantial limitations exist on the visual system’s ability to process various forms of redundant information.