E. Leslie Cameron

Sex differences and reproductive hormone influences on human odor perception.

The question of whether men and women differ in their ability to smell has been the topic of scientific investigation for over a hundred years. Although conflicting findings abound, most studies suggest that, for at least some odorants, women outperform men on tests of odor detection, identification, discrimination, and memory. Most functional imaging and electrophysiological studies similarly imply that, when sex differences are present, they favor women. In this review we examine what is known about sex-related alterations in human smell function, including influences of the menstrual cycle, pregnancy, gonadectomy, and hormone replacement therapy on a range of olfactory measures. We conclude that the relationship between reproductive hormones and human olfactory function is complex and that simple associations between circulating levels of gonadal hormones and measures of olfactory function are rarely present.

Pregnancy and olfaction: a review.

Many women report a heightened sense of smell during pregnancy. Accounts of these anecdotes have existed for over 100 years, but scientific evidence has been sparse and inconclusive. In this review, I examine the literature on olfactory perception during pregnancy including measures of self-report, olfactory thresholds, odor identification, intensity and hedonic ratings, and disgust. Support for a general decrease in olfactory thresholds (increase in sensitivity) is generally lacking. There is limited evidence that some suprathreshold measures of olfactory perception, such as hedonic ratings of odors, are affected by pregnancy, but these effects are idiosyncratic. In this review, I explore the hypotheses that have been put forth to explain changes in olfactory perception during pregnancy and provide suggestions for further research.

“Let Me Show You a Trick!”: A Toddler's Use of Humor To Explore, Interpret, and Negotiate Her Familial Environment During a Day in the Life

Abstract Children employ different types of humor as they explore, interpret, and negotiate their environments. Whereas an appreciation of verbal incongruity has been a hallmark of older preschooler humor (e.g., McGhee, 1989), more recently, other violations of expectations and clowning also have been identified as ubiquitous during the first two years of life (e.g., Loizou, 2005; Reddy, 2001). We examined the pragmatics of one 30-month-old girls humor, and determined how it interactively harnessed the cognitive, linguistic, and socio-emotional resources available to her negotiations within her familial context. Using the methodology of a Day in the Life of a toddler in early childhood (Gillen et al., 2006), the childs entire waking day was videotaped, and all interactions were transcribed and analyzed. We identified many instances of humor, and categorized them into four major types: clowning, teasing, jokes and playful language, and physical actions. Humor served both socio-emotional and cognitive-linguistic functions, and we confirmed Reddys (2001) finding that early humor is interpersonally co-constructed: When humor operates within the childs inter-mental development zone (Mercer, 2000), it serves to inform her or his intra-mental growth; the inter-mental precedes and enables the intra-mental.

Resilient Youths Use Humor to Enhance Socioemotional Functioning During a Day in the Life

In order to extend previous early years humor research into early adolescence, the authors adapted an innovative ecological research method such that at-risk adolescents could be filmed during an entire waking day in their life. Community youth advocates nominated one 15-year-old female and one 14-year-old male as doing well despite adverse circumstances. We examined the types and functions of these youths’ humor within their social contexts. Their humor included joking, teasing, physical play, light tones, irony, sarcasm, and mocking/parody. Humor served many socioemotional roles, such as navigating complex socially sensitive topics and situations, and facilitating affiliation with friends and family. Humor assists in traversing challenging social terrain and can serve as a protective factor under risky circumstances.

Pregnancy Does Not Affect Human Olfactory Detection Thresholds

Hyperosmia is suspected in pregnancy; however, no empirical study using validated measures of olfactory function has clearly confirmed the anecdotal reports of this phenomenon. The goal of the current study is to compare the olfactory sensitivity of pregnant women to that of nonpregnant women and men. All participants rated their sense of smell and pregnant women listed the odors to which they were most sensitive. Detection thresholds were measured using a well-validated protocol. A group of pregnant and nonpregnant women was studied longitudinally using a signal detection procedure designed to detect small differences in sensitivity. Pregnant women, particularly in the 1st trimester, rated their sense of smell to be higher than nonpregnant women and men and indicated many (primarily unpleasant) odors to which they were more sensitive. Women rated their sense of smell higher than men. However, there was no sex difference in thresholds and neither thresholds nor signal detection measures of sensitivity were significantly affected by either sex or pregnancy status. The implications of the lack of relationship between self-report and measures of olfactory sensitivity, particularly in pregnancy, are discussed.

Olfactory perception in children

The ability to smell is important for protection from danger and quality of life, even in children. Although smell loss is rare in children, it can be indicative of some childhood disorders and may be useful for understanding some disorders. This paper reviews the methods and results of behavioral testing olfaction in children, with an emphasis on odor identification, the most common method of assessing the sense of smell in both children and adults. The Pediatric Smell Wheel® is described as a relatively new and powerful tool for testing olfaction in children as young as 4 years of age. An example of its use in testing children with a childhood disorders (autism spectrum disorder, ASD) is provided in addition to a review of the literature on smell function in ASD. It is possible to reliably test sense of smell in children as young as 4 years old and many studies have shown that performance improves with age and can be impacted by childhood disorders. Sex differences in children are briefly discussed. Finally, the paper suggests other methods of testing olfaction in children, such as odor discrimination, that depend less on cognitive factors, which may enhance our understanding of the olfactory capabilities of young children.

The Accuracy, Consistency, and Speed of Odor and Picture Naming

IntroductionOdor identification, the ability to select the correct odor from a list of names, is a common method of measuring sense of smell in humans. Performance on such tasks depends upon a variety of factors, but can be quite good. On the other hand, people find it very difficult to generate names for odors in the absence of contextual cues. Picture identification and naming, by contrast, are much easier. Two questions remain about odor naming: (1) Do people attempt to name odors, even when they are unfamiliar or uncommon, and are they consistent in naming? and (2) What is the latency to name odors compared to pictures?MethodThe current study examined people’s ability and attempts to name common and uncommon odors and pictures, as well as the speed and consistency (some stimuli were presented twice) of their responses.ResultsParticipants provided names for most odors and pictures, even though some were uncommon. Participants were able to name less than half of the common odors accurately, but provided names for almost all of the (even uncommon) pictures. Common pictures were named with perfect accuracy and consistency and in about a second, but naming of uncommon pictures and common and uncommon odors was not consistent and required several seconds.ConclusionThe results confirm and extend our understanding of the difficulty of naming odors, particularly relative to the ease of naming pictures.ImplicationsThese results suggest that odor naming is a laborious process that may have little ecological value.