Control of attention around the fovea.

Three experiments tested young adults' abilities to use size and location cues to find and identify a target letter in a visual field containing 8 to 12 letters. Location cues (relatively near to or far from the fovea) and size cues (relatively large or small) were given before the display. Compared with response times on neutral, no-cue trials, location and size cues produced independent cost and benefit effects. The best fitting quantitative models allow attentional resources to be distributed in ringlike areas varying in distance from the fixation point, within which further selection of items by their relative size is possible.

Recurrent symptoms: well-being and management.

Although most older adults report one or more symptoms of a chronic health problem, little attention has been paid to the report of these symptoms over time and whether different symptom patterns affect well-being and symptom management in community-dwelling elders. Therefore, this study examined whether community-dwelling older adults in Ohio, U.S.A. who experience consistently recurring (a) arthritis or (b) cardiopulmonary symptoms report more depression and worse self-assessed health and show more symptom management than those who report inconsistent symptoms and if there are differences in well-being and symptom management over time. This secondary analysis used longitudinal data collected from a random sample of 387 older adults who reported their health complaints in four interviews over 27 months time. Subjects were included in this analysis if they reported either arthritis (n = 321) or cardiopulmonary (n = 232) symptoms at one or more times during 27 months, and then were classified as having either consistent (occurring at all four time points) or intermittent/inconsistent (occurring at three or fewer time points) symptoms. Data analysis included t-tests, chi-square tests, and Repeated Measures ANOVA. Results indicate that those with consistent symptoms reported greater depression and worse self-assessed health than those with less consistent symptoms. Specifically, those with consistent cardiopulmonary symptoms became more depressed over time. Those with consistent cardiopulmonary complaints were more likely than those with an inconsistent pattern to use an illness label to describe their symptoms. Those with consistent arthritis symptoms tended to use more self-care at all time points, to label their symptoms as an illness, and were more likely to consult a physician as their symptoms persisted. The implications of symptom recurrence on well-being, symptom management and the concept chronicity are discussed.

Automatic and voluntary control of attention in young and older adults.

Young and older adults searched for a target character in a 3-item display. On each trial, both a symbolic cue (arrow at fixation) and a spatial cue (abrupt onset of one item) could indicate the target's position. Participants were told to use the central arrow cue on all trials because it had 75% validity. The onset cue also had 75% validity for half the participants and 25% validity for the other half. Both age groups showed about the same cost and benefit effects for the central arrow cues, but the abrupt onsets had much larger cuing effects for older adults. Young adults were able to suppress at least partially an automatic attentional response to an abrupt onset item when the arrow cue preceded the onset and had a higher validity than the onset cue. Older adults appeared to be less able to inhibit their responses to abrupt onsets and to disengage their attention from invalid onset cues than were the young adults.

eXpTools: a C++ class library for animation, tachistoscopic presentation, and response timing.

The eXpTools Library is a general-purpose tool for developing psychological experiments that combine animation with tachistoscopic presentation. The library's C++ classes and assembly language functions are specialized for the creation of visual response time experiments. Its use is limited to variants of standard, 16-color, VGA high-graphics modes. However, it extends the capabilities of these modes through bit-plane animation techniques and a new, nonstandard, high-resolution graphics mode that will work with standard VGA cards and register-compatible cards. These techniques make possible a powerful animation class for managing complex animation or tachistoscopic presentations consisting of hundreds or thousands of frames. The library also combines such features as page flipping, screen blanking, video-refresh synchronization, interrupt-driven millisecond timing, interrupt-driven keyboard response collection, graphics primitives, bitmaps, and screen fonts. Utilities allow for the conversion of PCX graphics files and the creation of new screen fonts from monochrome bitmap files. The technologies and techniques underlying the library are presented along with an example program.

Voluntary allocation versus automatic capture of visual attention.

Is there a difference in the kind of attention elicited by an abrupt-onset peripheral cue and that elicited by an instruction (e.g., a central arrow cue) to move attention to a peripheral location? In Experiment 1, we found that peripheral cues are no more effective in orienting attention than are central cues. No evidence was found for separable attentional systems consisting of a volitional response to central cues and an automatic response triggered only by peripheral cues. Rather, an identical or similar attentional process seems to be activated by either type of cue, although perhaps in different ways. Peripheral cues seem to have an automatic component, however, in that once attention is engaged by a peripheral cue, it cannot easily be disengaged for refocus elsewhere. In Experiment 2, after several sessions of practice, subjects were able to circumvent automatic attentional capture by an abrupt-onset peripheral cue and to volitionally redirect the focus of attention. Thus, attentional capture by abrupt-onset stimuli is not strongly automatic.

Relative effectiveness of central, peripheral, and abrupt-onset cues in visual attention.

The relative effectiveness of central arrow, peripheral arrow, and abrupt-onset cues was assessed in a character recognition task. On each trial, either a central or a peripheral arrow cue was presented 0, 100, or 200 msec before the appearance of a three-digit display. Two of the digits were "uncamouflaged" from previous figure-eight masks, whereas the third digit appeared abruptly in a previously empty space. Four different groups of subjects were run in factorial combinations of high or low expected validities for arrow and onset cues. In Experiment 1, arrow cues were located centrally, near the fixation point. Abrupt onsets showed larger cost-plus benefits than central arrows, except when subjects expected the central cues to have higher validity than the onsets. In Experiment 2, arrow cues were located peripherally, near the display digits, and abrupt onsets were again more effective in capturing attention except when peripheral cues had higher validity and led the onsets by 100 msec or more. In both experiments, the relative effectiveness of abrupt onsets decreased with arrow SOA. The results were consistent with a model in which automatic and voluntary processes interact in their control of attentional resources.

Tradeoffs between attentional effects of spatial cues and abrupt onsets.

We determined the relative effectiveness and tradeoffs among central, peripheral, and abrupt onset cues in directing attention to a potential target character. Central cues were arrows located at the fixation point, whereas peripheral cues were arrows occurring about 3 degrees away from fixation, near the location of a potential target. These were contrasted with the abrupt onset of an ambiguous part of a character, which later was filled in to reveal a target or a distractor item. Each trial included an arrow cue and an abrupt onset cue, and both expected cue validities and cue-character SOAs were varied factorially. The results showed that, in general, abrupt onsets captured attention more effectively than either central or peripheral arrow cues. However, tradeoffs among separate cue effects indicated that the power of abrupt onsets to capture attention automatically could be overridden by a high-validity spatial cue presented in advance of the onset character. Tradeoffs between the effects of central and abrupt onset cues were additive, indicating that endogenous and exogenous cues have their main effects at different levels in the visual attention system. Peripheral cues and abrupt onsets showed mainly interactive effects, however, consistent with the idea that both types of cues have exogenous components that affect a common pool of attentional resources.

Effect of gentamicin dosing interval on efficacy of penicillin or ceftriaxone treatment of experimental endocarditis due to penicillin-susceptible, ceftriaxone-tolerant viridans group streptococci.

The efficacy of ceftriaxone or penicillin alone or combined with gentamicin at different dosing intervals was evaluated in experimental endocarditis due to a penicillin-susceptible, ceftriaxone-tolerant strain of Streptococcus sanguis I. The difference between monotherapy with ceftriaxone and procaine penicillin approached statistical significance (P = 0.052). Ceftriaxone combined with gentamicin administered as a single daily dose was less effective than was procaine penicillin combined with gentamicin administered in a single daily dose or in three divided doses.