olfaction

‘Love like you’ve never been hurt.’ –Mark Twain

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Explicit communication involves the deliberate, conscious choosing of words and signals to convey a specific message to a recipient or target audience. […] Much of human communication is also implicit, and occurs subconsciously without overt individual attention. Examples include nonverbal communication and subconscious facial expressions, which have been argued to contribute significantly to human communication and understanding. […] Additionally, recent studies conducted by evolutionary psychologists and biologists have revealed that other animals, including humans, may also communicate information implicitly via the production and detection of chemical olfactory cues. Of specific interest to evolutionary psychologists has been the investigation of human chemical cues indicating female reproductive status. These subliminally perceived chemical cues (odors) are often referred to as pheromones.

For two decades, psychologists studying ovulation have successfully employed a series of “T-shirt studies” supporting the hypothesis that men can detect when a woman is most fertile based on olfactory detection of ovulatory cues. However, it is not known whether the ability to detect female fertility is primarily a function of biological sex, sexual orientation, or a combination of both.

Using methodologies from previous T-shirt studies, we asked women not using hormonal contraceptives to wear a T-shirt for three consecutive nights during their follicular (ovulatory) and luteal (non-ovulatory) phases. Male and female participants of differing sexual orientations then rated the T-shirts based on intensity, pleasantness, and sexiness.

Heterosexual males were the only group to rate the follicular T-shirts as more pleasant and sexy than the luteal T-shirts. Near-significant trends also indicated that heterosexual men and non-heterosexual women consistently ranked the T-shirts, regardless of menstrual stage, to be more intense, pleasant, and sexy than did non-heterosexual men and heterosexual women.

{ Journal of Social, Evolutionary, and Cultural Psychology | PDF }

Her face against the pane in a halo of hurried breath

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Did you know that around 85% of humans only breathe out of one nostril at a time? This fact may surprise you, but even more remarkable is the following: our body follows a pattern and switches from breathing out of one nostril to the other in a cyclical way. Typically, every four hours it switches from left to right, or right to left.

{ United Academics | Continue reading }

images { John Stezaker, The Voyeur, 1979 | 2 }

I saw the Spanish cavalry at La Roque it was lovely

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Pleasantness of an odor is attributed mainly to associative learning: The odor acquires the hedonic value of the (emotional) context in which the odor is first experienced. Associative learning demonstrably modifies the pleasantness of odors, particularly odors related to foods. Experimentally, classical conditioning paradigms (Pavlovian conditioning) have been shown to modify the responses to odors, not only in animals but also in humans (olfactory conditioning).

In olfactory conditioning an olfactory stimulus is the conditioned stimulus that has been paired with an unconditioned stimulus (e.g., taste). For instance, the pleasantness of odors with originally neutral hedonic value was improved after the odors were paired as few as three times with the pleasant unconditioned stimulus, sweet taste. This type of conditioning, where liking of a stimulus changes because the stimulus has been paired with another, positive or negative, stimulus is called evaluative conditioning.

Naturally occurring evaluative conditioning may be important also in modifying the pleasantness of a partner’s body odors (conditioned stimulus) that are encountered initially during affection and sexual intercourse (unconditioned stimulus), because the sexual experiences presumably provide strong, positive, emotional context.

Searches for human pheromones have focused on androstenes, androgen steroids occurring in apocrine secretions, for example, axillary (underarm) sweat, motivated by the fact that one of them, androstenone, functions as a sex pheromone in pigs. However, some 20–40% of adult humans, depending on age and sex, cannot smell androstenone, although their sense of smell is otherwise intact. To date, no convincing evidence exists to demonstrate that any single compound is able to function as a sexual attractant in humans, although several other types of pheromonal effects (e.g., kin recognition) have been observed.

While many studies have explored potential physiological and behavioral effects of the odors of androstenes, we asked a different question: Could an odor (conditioned stimulus) that is perceived during sexual intercourse gain hedonic value from the intercourse experience (presumably a pleasant unconditioned stimulus) through associative learning? While experimental challenges limit human studies of this kind, we approached the question by asking young adults, randomly sampled regarding the level of sexual experience and olfactory function, to rate the pleasantness of body-related (androstenone and isovaleric acid) and control odorants (chocolate, cinnamon, lemon, and turpentine). We compared the responses of participants with and without experience in sexual intercourse and hypothesized that those with intercourse experience would rate the pleasantness of the odor of androstenone higher than would those without such experience. […]

The results suggest that, among women, sexual experience may modify the pleasantness of the odor of androstenone.

{ Archives of Sexual Behavior/Springer | Continue reading }

No, that would state that I exist on a linear timeline, while you seek to compare past facts vs future forecasts

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The study, reported in The Journal of Neuroscience [2007], provides the first direct evidence that humans, like rats, moths and butterflies, secrete a scent that affects the physiology of the opposite sex. (…)

He found that the chemical androstadienone — a compound found in male sweat and an additive in perfumes and colognes — changed mood, sexual arousal, physiological arousal and brain activation in women.

Yet, contrary to perfume company advertisements, there is no hard evidence that humans respond to the smell of androstadienone or any other chemical in a subliminal or instinctual way similar to the way many mammals and even insects respond to pheromones, Wyart said. Though some humans exhibit a small patch inside their nose resembling the vomeronasal organ in rats that detects pheromones, it appears to be vestigial, with no nerve connection to the brain.

“Many people argue that human pheromones don’t exist, because humans don’t exhibit stereotyped behavior. Nonetheless, this male chemical signal, androstadienone, does cause hormonal as well as physiological and psychological changes in women.” (…)

Sweat has been the main focus of research on human pheromones, and in fact, male underarm sweat has been shown to improve women’s moods and affect their secretion of luteinizing hormone, which is normally involved in stimulating ovulation.

Other studies have shown that when female sweat is applied to the upper lip of other women, these women respond by shifting their menstrual cycles toward synchrony with the cycle of the woman from whom the sweat was obtained.

{ ScienceDaily | Continue reading }

By emotion I mean the modifications of the body, whereby the active power of the said body is increased or diminished, aided or constrained, and also the ideas of such modifications.

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The memory for odors has been studied mostly from the point of view of odor recognition. In the present work, the memory for odors is studied not from the point of view of recognition but from the hedonic dimension of the sensation aroused by the stimulus.

Hedonicity is how we like or dislike a conscious experience. Hedonicity seems to be especially predominant with olfactory sensation. What will be studied, therefore, is the capacity to remember stimuli as a function of the amount of pleasure or displeasure aroused by the stimuli – in our case, odors. In the following pages, the term “pleasure/displeasure” will be considered as describing the hedonic dimension of consciousness. (…)

The “goodness” of a person’s memory for a given event is known to depend on variables such as the nature of the event, the context within which it occurs, initial encoding and subsequent recoding operations performed on the input, and the extent to which retrieval cues match these operations. It was shown also that slides arousing stronger emotions tended to be better remembered.

The question addressed in the present experiment concerned the role of perceived or felt pleasure or displeasure evoked by the experienced stimulus events. The hypothesis was that the hedonic dimension of cognition, aroused by the events at encoding and stored in memory, plays an important role in remembering of the events.

Pleasure/displeasure and emotion have long been recognized as dominant features in odorant stimulation, description, and memory. EEG recordings demonstrate the deep influence of olfactory stimuli on the brain. “The most important function of the nose may be not in transmitting messages about the outside world, but in motivating the organism after the message has been received” (Engen, 1973); that function being already present in the newborn and even intra utero.

Animal experiments have shown that odors followed by a reward were better remembered than non-rewarded odors, which is a clue that memory privileges usefulness. It was demonstrated also that recollections evoked by odors are more emotional than those evoked verbally, that verbal codes are not necessary for odor-associated memory and finally that pleasant odors enhance approach behavior due to their hedonic dimension. These findings suggest that the sensory stimulus in olfaction should provide a favorable paradigm to test the hypothesis that hedonicity is a potent factor for storing a piece of information into memory.

{ International Journal of Psychological Studies | Continue reading }

She even caught me on camera (It wasn’t me)

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Whenever we are doing something, one of our brain hemispheres is more active than the other one. However, some tasks are only solvable with both sides working together.

PD Dr. Martina Manns and Juliane Römling of the Ruhr-Universität Bochum are investigating, how such specializations and co-operations arise. Based on a pigeon-model, they are proving for the first time in an experimental way, that the ability to combine complex impressions from both hemispheres, depends on environmental factors in the embryonic stage. (…)

First the pigeons have to learn to discriminate the combinations A/B and B/C with one eye, and C/D and D/E with the other one. Afterwards, they can use both eyes to decide between, for example, the colours B/D. However, only birds with embryonic light experience are able to solve this problem.

{ EurekAlert | Continue reading }

Imagine the smell of an orange. Have you got it? Are you also picturing the orange, even though I didn’t ask you to? Try fish. Or mown grass. You’ll find it’s difficult to bring a scent to mind without also calling up an image. It’s no coincidence, scientists say: Your brain’s visual processing center is doing double duty in the smell department.

{ Inkfish | Continue reading }

‘The illusion which exalts us is dearer to us than ten thousand truths.’ –Pushkin

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Very little research has investigated whether smells really do evoke vivid and emotional memories, more than other sensory cues. What follows is a new, rare attempt. (…)

“It could be argued that a necessary implication of the Proust phenomenon is that odors are more effective triggers of emotional memories than other-modality triggers,” the researchers said. “Under such strong assumptions the results reported here do not confirm the Proust phenomenon. Nonetheless, our findings do extend previous research by demonstrating that odor is a stronger trigger of detailed and arousing memories than music, which has often been held to provide equally powerful triggers as odors.”

{ BPS | Continue reading }

photo { Stephanie Gonot }

Never lose your shadow

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Given this importance of the flavors we learn to like, it seems to me remarkable, and unfortunate, that most people are unaware that the flavors are due mostly to the sense of smell and that they arise largely from smells we detect when we are breathing out with food in our mouths. (…)

The role of retronasal smell in flavor was finally put on the map by Paul Rozin, a psychologist at the University of Pennsylvania, in an article in 1982. As he phrased it, we need to recognize that smell is not a single sense but rather a dual sense, comprising orthonasal (breathing in) and retronasal (breathing out) senses. He devised experiments to show that the perception of the same odor is actually different depend­ing on which sense is being used. Subjects trained to recognize smells by sniffing them had difficulty recognizing them when they were introduced at the back of the mouth.


{ Neurogastronomy: How the Brain Creates Flavor and Why It Matters | Continue reading }

One day you’ll realize that we’re not strangers

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Sexual infidelity can be costly to members of both the extra-pair and the paired couple. Thus, detecting infidelity risk is potentially adaptive if it aids in avoiding cuckoldry or loss of parental and relationship investment.

Among men, testosterone is inversely related to voice pitch, relationship and offspring investment, and is positively related to the pursuit of short-term relationships, including extra-pair sex.

Among women, estrogen is positively related to voice pitch, attractiveness, and the likelihood of extra-pair involvement.

Although prior work has demonstrated a positive relationship between men‟s testosterone levels and infidelity, this study is the first to investigate attributions of infidelity as a function of sexual dimorphism in male and female voices.

We found that men attributed high infidelity risk to feminized women‟s voices, but not significantly more often than did women. Women attributed high infidelity risk to masculinized men‟s voices at significantly higher rates than did men. These data suggest that voice pitch is used as an indicator of sexual strategy in addition to underlying mate value.

{ Evolutionary Psychology | Continue reading | PDF }

artwork { Raphaelle Peale, Venus Rising from the Sea—A Deception, 1822 }

‘I am the first to have sensed, to have had the flair to scent out, falsehood as falsehood.’ –Nietzsche

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{ A surprising new study suggests that people can track a scent across a grassy field–at least if they’re willing to get down on their hands and knees and put their noses to the ground. | Science | full story | Thanks Tim }

So if you sprig poplar you’re bound to twig this

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Most people detect a distinct sulfurous odor in their urine shortly after eating asparagus. However, there are some who seemingly do not notice the unpleasant odor.

Up until now, it has been unclear whether this is because these individuals do not produce the odor or because they cannot smell it.

Addressing this mystery from several angles, scientists from the Monell Center first used sophisticated sensory testing techniques to show that both explanations apply: approximately eight percent of the subjects tested did not produce the odorous substance, while six percent were unable to smell the odor. One person both did not produce the odor and was unable to smell it.

{ EurekAlert | Continue reading }

So. While you’re adamant evar. Wrhps.

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Odors can be a subtle factor affecting human mating, similar to the behavior of other animals. Monitoring the responses of men after smelling t-shirts worn by ovulating women, non-ovulating women and some not worn at all, they observed reactions and biological changes. This study provides evidence that ovulatory cues are detectable.

{ Sage Insight | Continue reading }

photo { Susan Meiselas }