Avery N. Gilbert

Hand preference and age in the United States

A survey of 1,177,507 U.S. men and women between the ages of 10 and 86 included questions regarding hand preference for writing and throwing. Three effects were observed. Individuals with at least some left motoric bias comprised a smaller percent of the population with advancing age. This finding provides large-scale confirmation of a previously described phenomenon. Among sinistrals, concordance for writing and throwing was 2.2 times as prevalent as left-writing with right-throwing, and 4.1 times as prevalent as right-writing with left-throwing. These sinistral subpopulations displayed distinct and stable prevalence prior to age 50 and changing patterns of prevalence subsequent to age 50. The results confirm a decrease with age in the prevalence of sinistrality, but indicate that age-specific rates of mixed- and left-handedness are distinct. The implications for hypotheses regarding age-related change in the prevalence of sinistrality are discussed.

National Geographic Smell Survey: Effects of Age Are Heterogenous

Does the world become less fragrant as we age? By analogy with vision and hearing, we might expect our olfactory sense to decline as we grow old. If so, does reduced olfactory ability reflect the normal aging process or the cumulative effect of a lifetime of disease and injury? Does aging take its toll on the olfactory periphery or on more central structures and processes? To answer such questions, olfactory perception must be considered across the full span of life, and across the spectrum of capacities that collectively constitute our sense of smell. There are few, if any, longitudinal studies of aging and olfaction. The longitudinal approach, while it has certain methodological advantages, tends to minimize age differences because of selective subject attrition.’ Cross-sectional analyses of olfaction are more common; however, these designs are subject to cohort effects.’ Among the latter, the two-sample design, which compares youthful and elderly subjects, may be the least robust, although it is often used (examples of studies in the chemical senses include references 2 and 3). Only a decade-by-decade analysis can provide estimates of onset and rate of de~l ine .~ Threshold determinations, magnitude estimation (of strength or hedonic quality), similarity judgments, and identification tasks are some of the measures available to characterize olfactory function. Yet most studies of aging and olfaction make use of only one such measure (see summary in Chauhan et ~ 1 . ~ ) . Reliance on a single testing method can compromise broader conclusions, as it has regarding olfactory deficits in Alzheimer’s disease.6 A more satisfying approach would be to incorporate a variety of olfactory measures and a variety of odorants in a single examination. We chose this multifaceted approach as the strategy of a Smell Survey undertaken in collaboration with the National Geographic Society and its membership publication, the National Geographic Magazine. Detection, intensity estimates, hedonic judgments, and identification ability were recorded in response to six microencapsulated odorants. We report here the results relevant to aging and olfaction.

Odor intensity and color lightness are correlated sensory dimensions

We previously found that untrained subjects make nonrandom color matches to odors and that the color matches are stable over time (Gilbert, Martin, & Kemp, 1996). Here we investigate further aspects of the cross-modal associations between vision and olfaction: whether perceptual dimensions of odor vary systemically with those of vision. Subjects matched Munsell color chips to five odors presented at three concentrations; they also rated odor intensity. Significant negative correlations between Munsell value and perceived odor intensity were found for three odors. The results suggest that stronger odors were associated with darker colors. The cross-modal relationship between vision and olfaction appears to be dimensional: Color lightness varies inversely with perceived odor intensity. This finding parallels the dimensional relations found between other modalities (e.g., lightness varies with loudness).

Auditory Pitch as a Perceptual Analogue to Odor Quality

Experiments in cross-modal matching suggest that smells can be arranged by odor quality along the color dimensions of hue and lightness Here we report that subjects readily adjust the loudness-equalized pitch of an auditory tone to match a stimulus odor The results allow odors to be arranged in sequence by their pitch-equivalents The tone matches appear to be based on perceptual features of olfaction other than stimulus intensity or pleasantness The results suggest that features of odor quality may be more accessible and structured than previously acknowledged.

Biological Rhythmicity of Nasal Airway Patency : A Re-examination of the 'Nasal Cycle'

Rhinomanometric observations of nasal airway patency were obtained for each nasal passage every 10 min throughout an uninterrupted 8-h session. The 49 airflow observations for each nasal passage were subjected to autocorrelation analysis, a statistical technique for quantifying periodicities in a temporal sequence of observations. No significant periodicities were found in any of the 16 subjects when the autocorrelation functions were interpreted by conventional statistical criteria. However, when less stringent criteria were applied, we found suggestive evidence for rhythmicity in one (7 subjects) or both nasal passages (2 subjects). The relationship in patency between the two sides of the nose was characterized with correlation coefficients. These correlations were significantly negative in 7 subjects, indicating bilateral reciprocity of patency. In addition, the correlations were significantly positive in one, and nonsignificant in 8 subjects. Only a minority of subjects (13%) displayed the classical nasal cycle, i.e., rhythmicity in both nasal passages as well as reciprocity of patency between passages.

Olfactory discrimination of mouse strains (Mus musculus) and major histocompatibility types by humans (Homo sapiens).

A series of experiments revealed that humans can use olfaction to discriminate closely related strains of mice, differing genetically only at the major histocompatibility gene complex (H-2). In Experiment 1, subjects were asked to distinguish between the whole-body odors of live mice. In Experiments 2 and 3, the odor source was mouse fecal pellets, and in Experiments 4 and 5, the odor source was mouse urine.

Postpartum and lactational estrus: a comparative analysis in rodentia.

Virgin rodents exhibiting cycling estrus have traditionally been used for comparative studies of reproductive behavior. However estrus occurs in other life-history contexts, some of which differ from cycling estrus (CE) in that (a) the female is disposed to behave both maternally and sexually and (b) they result in litter overlap (i.e., the simultaneous gestation and lactation of two litters). In this report, two of these other modes of estrus are examined, with emphasis on their evolutionary and ecological implications. By means of a literature search of the order Rodentia, postpartum estrus (PPE) and lactational estrus (LE) were documented in 15 families, 71 genera, and 141 species. Analysis of these data showed that PPE and LE were nonrandomly distributed across taxa. They were statistically overrepresented in the family Cricetidae and underrepresented in squirrels (Sciuridae) and in pocket mice and kangaroo rats (Heteromyidae). Analysis of the phenotypes by which PPE and LE are achieved suggests important differences between them and CE in several parameters of female reproductive effort and breeding strategy, including maternal and copulatory behavior, optimal timing of litters, and hormonal control of heat and lactation.

Quantitative Assessment of Olfactory Experience during Pregnancy

&NA; Results of the National Geographic Smell Survey were used to investigate the effects of pregnancy on olfactory perception and odor‐related behavior. The responses to test odors and survey questions of 13,610 pregnant and 277,228 nonpregnant U.S. women between 20 and 40 years of age were analyzed. In comparison to nonpregnant women, pregnant women rated their own sense of smell lower, more often rated the test odors less pleasant smelling, more often classified the test odors as inedible, were less likely to report odor‐evoked memories, and used perfume and cologne less frequently. Differences in odor detection and intensity rating did not favor either group.

Sex Differences in Task Performance Associated with Attention to Ambient Odor

The effects of ambient odor (pleasant, unpleasant, none); odor suggestion (present, absent); and sex of subject on mood and performance measures were explored in a 3 x 2 x 2 experimental design. A total of 40 men and 40 women performed a clerical task and a speed and accuracy task (digit deletion), filled out self-evaluations of mood, predicted performance, and rated the odor quality of the test room. Ambient odor conditions significantly affected room smell ratings, but they had no effect on performance or mood. Odor suggestion produced a significant sex-related interaction effect on the digit deletion task, irrespective of actual ambient odor. The results are discussed with respect to sex differences observed in laboratory studies and in epidemiological investigations of multiple chemical sensitivity and sick building syndrome.

Sex, handedness and side of nose modulate human odor perception

Multidimensional scaling was used to analyze odor similarity judgments obtained by monorhinic (single nostril) stimulation from normal subjects (N = 52), equally partitioned by sex and handedness. Neither sex nor handedness nor side of nose appeared to alter the position of stimuli on a two-dimensional map of odor similarity. However, women produced significantly more consistent maps than men. This result was not due to differential utilization of axes in the multidimensional perceptual space, nor to differences in verbal labeling. Left versus right nostril asymmetries were significantly greater in dextrals.