Mood and experimentally-induced respiratory virus infections and illnesses

Abstract

The research described in this paper examined the relationship between mood and experimentally-induced upper respiratory virus infections and illnesses. The first aim was to determine whether pre-challenge mood was related to susceptibility to infection and illness. There was no evidence of an association in any of the trials. A second aim of the research was to examine the nature of the mood changes induced by the different viruses. Subjects with influenza showed a general increase in negative affect. Those who developed a cold following challenge with a coronavirus reported a drop in arousal but little change in other aspects of mood. Colds following challenge with rhinoviruses and respiratory syncytial viruses produced little change in mood. There was little evidence of sub-clinical infections changing mood. However, mood changes were also reported after the symptoms of a coronavirus cold had gone. These results demonstrate selective effects of upper respiratory viruses on mood and show that the changes are not confined to times when the primary symptoms are present. This agrees with the pattern obtained in studies of performance change.     

Fighting patterns in young coyotes: Initiation,escalation, and assessment

The fighting patterns of young coyotes were studied and 2,350 fights were analyzed. Our results can be summarized as follows: 1) No major injuries were sustained by any of the infants, even in unritualized bouts. 2) In pairs, there was no relationship between social rank and the proportion of fights that were initiated by either animal. 3) Dominant animals were more likely than subordinate individuals to escalate first (perform the first unprovoked dangerous move) during short interactions and to escalate and then subsequently win short fights. 4) Highest-ranking (alpha) individuals in litters did not fight the most. 5) Alpha individuals initiated 73% of the fights in which they partook. Alpha coyotes initiated and then won 86% of the contests that they initiated. 6) For fourth-ranking coyotes in litters, there was a perfect positive correlation between the proportion of times that they initiated fights and the proportion of times that they initiated and then won encounters. They initiated interactions least with the first- to third-ranking animals. 7) Alpha and fourth-ranking animals escalated about the same proportion of the time, but alpha coyotes escalated and then won a greater proportion of fights. 8) Both alpha and fourth-ranking animals initiated and then escalated the greatest proportion of time with individuals nearest in rank, with whom they may have experienced the greatest difficulty in assessing relative social standing. 9) Our data suggested that individuals, especially in litters, were able to make pre-fight assessments but that they were not perfect with respect to this ability. During-fight assessments appeared to be easier to make, using escalation to test an opponent.     

Repetition blindness and homophone blindness in young and older adults

We tested age effects on repetition blindness (RB), defined as the reduced probability of reporting a target word following presentation of the same word in a rapidly presented list. We also tested age effects on homophone blindness (HB), in which the first word is a homophone of the target word rather than a repeated word. Thirty young and 28 older adults viewed rapidly presented lists of words containing repeated, homophone, or unrepeated word pairs and reported all of the words immediately after each list. Older adults exhibited a greater degree of RB and HB than young adults using a conditional scoring method that provides certainty that blindness has occurred. The existence of RB and HB for both age groups, and increased blindness for older compared to young adults, supports predictions of a binding theory that has successfully accounted for a wide range of phenomena in cognitive aging.     

A rapid technique to assess the resting states of the eyes and other threshold phenomena: The Modified Binary Search (MOBS)

A technique was developed to automate subjective measurement of the resting states of the eyes. This technique, the Modified Binary Search (MOBS), evolved from the binary search and a commonly used manual bracketing technique. The procedure is mathematically and logically simple, and it requires minimal storage and computation capabilities. Monte Carlo simulations indicate that the MOBS procedure provides more precise measures with fewer stimulus presentations than conventional staircases. It is also relatively insensitive to response errors.     

Evidence for the persistence of visual guidance information

An earlier study from our laboratory provided initial support for the hypothesis that information facilitating visual guidance persists in the absence of retinal stimulation. The present study supports and extends this hypothesis with three experiments in which visually occluded subjects positioned a point of light at the location of a previously viewed target and also walked in the direction of a previously viewed path. In both tasks, performance was possible following occlusion, and in all cases, performance slowly and significantly decreased with longer durations of occlusion. This decay in performance was gradual and had a “half-life” of greater than 15 sec. Absolute performance was correlated across tasks. The effect of occlusion on absolute error in the localization performance was relatively stable within individuals over a 3-week period. The biological utility of guidance information persistence is discussed along with implications for space constancy, illusions of motion, and problems of disorientation.     

Age differences in estimating vehicle velocity

Automobile accidents among older adults may be related to difficulties in judging the speed of other vehicles. To examine this possibility, 3 groups of observers in the young adult, middle-aged, and older adult age ranges were asked to estimate the velocity of an isolated automobile traveling at 15-50 mph (24-80 kph). Across all age groups, perceived and actual velocity were related by a power function with an exponent of 1.36. Age was significantly and positively correlated with intercepts, but negatively correlated with exponents; that is, older observers showed less sensitivity to changes in actual velocity. Results bear on the issues of ontogenetic changes in accident involvement and sensitivity to motion.     

Highlighting human form and motion information enhances the conspicuity of pedestrians at night

Exploring how biological motion can make pedestrians more conspicuous to drivers at night, one-hundred-and-twenty participants were driven along an open-road route at night and pressed a button whenever they recognized that a pedestrian was present. A test pedestrian wearing black clothing alone or with 302 cm2 of retroreflective markings in one of four configurations either stood still or walked in place on an unilluminated sidewalk. Participants' response distances were maximal for the full biological-motion configuration and remained surprisingly long when convenient subsets of reflective markers were positioned on the pedestrian's ankles and wrists. When the pedestrian wore a reflective vest, the responses were no better than when he wore no reflective markings. The biological-motion advantage actually results from interacting form-perception and motion-perception mechanisms. These results confirm that basic perceptual phenomena-observers' sensitivity to human form and motion can be harnessed to reduce an important problem of traffic safety.     

The Effects of Distractor Words on Naming Pictures at the Subordinate Level

Three experiments are reported in which participants are asked to name pictures at the subordinate level (e.g. POODLE) whilst ignoring a distractor word. In Experiment 1, the distractor words included the names of other exemplars from the same basic-level category (e.g. spaniel). Naming latencies were prolonged in this condition, relative to unrelated conditions. In Experiment 2, the distractor words included the correct basic level names (e.g. dog) and the names of related basic level objects (e.g. cat). Subordinate naming latencies were faster in these conditions than in unrelated conditions, suggesting that basic level names can be eliminated as competitors and that it can even be useful to have simultaneous activation of the correct basic level representation when retrieving subordinate names. Finally, Experiment 3 showed that when the names of subordinate objects from a related basic-level category (e.g. koala) are printed on objects, subordinate naming latencies are again delayed when compared with unrelated conditions. The results are discussed with reference to current models of object name retrieval.