Pleasantness

A. The correlation between the eNose pleasantness prediction values of 22 odorant mixtures (essential oils) and the values obtained from human participants. Each dot represents an eNose measurement (many dots overlay) B. The result of the classification algorithm when removing all odors with medium pleasantness ratings (below and above 1/3 and 2/3 of the pleasantness scale respectively).

pleasantness

A. The correlation between the eNose pleasantness prediction values of 21 odorants and the values obtained from human participants. Each dot represents an eNose measurement (many dots overlay) B. The result of the classification algorithm when removing all odorants with medium pleasantness ratings (below and above 1/3 and 2/3 of the pleasantness scale respectively).

Up to this point, we considered a continuous scale of odorant pleasantness. Naturally, the correlation between individual human subjects, as well as between human subjects and machine, was lower for ambiguous or intermediately rated odorants. Therefore, we now set out to ask how the eNose would perform if we restricted our analysis to the categorically pleasant and unpleasant odors.

A. Odorant-specific pleasantness ratings for native Ethiopians (blue), native Israelis (brown), and eNose (pink). The blue stars on the upper x axis denote the 7 odorants where native Ethiopians and native Israelis significantly differed in their pleasantness ratings. Note that for odors #6 #18 and #19 the pink line (eNose) is in fact closer to the native Ethiopians than to the native Israelis even though the eNose was tuned on a separate group of native Israelis. B. The correlation between the eNose pleasantness prediction values of 22 odorant mixtures (essential oils) and the values obtained from native Ethiopians. Each dot represents an eNose measurement (many dots overlay). Comparing Figure 2a to 5b reveals that native Israeli participants rated more at the middle of the VAS scale and native Ethiopians rated more at the scale extremes.

Because the native Ethiopians and native Israelis significantly differed in their pleasantness ratings for only 7 odorants, this is too small a subgroup for independent statistical analysis. However, a descriptive observation of this subset of odorants remains informative in that for several of the odorants with significant differences, the eNose prediction was in fact closer to the estimates of the native Ethiopians than to the estimates of the native Israelis (e.g., odorants #6,18 and #19 in Figure 5A). This suggests that although the eNose was initially tuned using an independent group of native Israelis, it nevertheless captured a culture-independent aspect of molecular structure that predicts pleasantness.

Here, we eNosed, digitized, and transmitted to receiving software, the smell-print of novel odorants, and in contrast to vision and audition, could predict their pleasantness with accuracy similar to that of a novel smeller. In other words, we could predict whether a person who we never tested before would like the odorant, and this prediction was consistent across Israeli and Ethiopian cultural backgrounds.

We argue that this difference was not a reflection of better hardware (in fact, an eNose is less precise than a modern camera or sound recorder), or better algorithms, but rather a reflection of a fundamental biological property of the sense of smell. These findings imply that unlike in vision and audition, in olfaction pleasantness is written into the molecular properties of the stimulus [17], and is thus better-captured by a machine.

This finding of hard-wired odorant pleasantness is in contrast to the popular notion that odorant pleasantness is both subjective and learned. We argue that in this respect olfactory pleasantness can be likened to visual color. Most would agree that color is hard-wired to wavelength within a predictable framework. That said, color perception can be influenced by culture [39], context [40], as well as by learning and memory [41]. All this does not detract from the hard-wire link between perceived color and wavelength. Similarly, we argue that olfactory pleasantness is hard-wired to molecular structure. That this link is modified through culture [32], [33], context [34], and learning [18], does not preclude the initial hard-wire aspects of this link, and it is this link that we have captured. Indeed, it is thanks to such hard-wiring that rodents bred for generations in predator-free laboratories are nevertheless averse to the smell of predators [42], human new-borns with no exposure to culture or learning are nevertheless averse to unpleasant odorants [22], [43], and that when tested out of context, odorant pleasantness is relatively constant across cultures as revealed here. To stress this point, we predict that if our odorants were presented to subjects within context, e.g., in foods, than the native Israeli and native Ethiopian participants may have then diverged in their pleasantness ratings. For example, peppermint may be rated as a pleasant smelling food in only one of two cultures. However, both cultures may then find peppermint equally pleasant when presented out of context in a jar. Indeed, many may wonder how the French can like the smell of their cheese. However, it is not that the French think the smell is pleasant per se, they merely think it is a sign of good cheese. To prove the point: the French don't make cheese smelling perfume! In other words, culture influences olfactory hedonics mostly in particular contexts. When out of context, odor pleasantness is less culturally variable, and we argue that it is this context-free component that was captured by our apparatus.

The rationale of the AMP is that when participants are asked to make pleasantness judgments of otherwise neutral target-stimuli, if they cannot use any other information to make their judgments, they will use the affective information elicited by the prime and misattribute it to the targets. This misattribution occurs in spite of the instructions to try to avoid any possible influence of the prime on their judgments of the target [46], [58].

Throughout human history, food consumption has been deeply tied to cultural groups. In the current paper, we present three studies that demonstrate social identification influences evaluations of food pleasantness that underlie food choice. Specifically, individual differences in social identification (Study 1) as well as experimentally manipulated identity salience (Study 2) were associated with the anticipated tastiness of identity-relevant foods. We also found that identity salience shaped perceived food pleasantness during consumption (Study 3). Moreover, shifts in anticipated and perceived food pleasantness mediated changes in overall desire (Studies 1 and 2) and willingness-to-pay for foods (Studies 3). These findings suggest that social identity can shape evaluations of food pleasantness, revealing a novel process whereby social identification can influence food choices. We discuss implications for theories of identity, decision-making, food consumption, and public health.

The purpose of the present study was to analyze the extent to which various processing scenarios influenced participants' rates of true and false memory recollection. Participants were placed in one of three conditions, storytelling, survival, or pleasantness, and then studied a list of common nouns. They were then instructed to comment on the words in a specific manner depending on the condition to which they were randomly assigned. Following this, participants completed a math distractor task, and were then asked to complete a free recall test for the previously studied words. The results indicated that participants in the storytelling condition correctly recalled more studied words than participants in either the survival or pleasantness conditions. Further, it was found that participants across all three conditions had not statistically significantly different rates of false memory.

Purpose: The current study sought to test the effects of essential oils on perception of exertion and exercise task pleasantness. Method: Thirty college students (24 females, 6 males) were recruited to perform a handgrip task. Participants were randomly assigned to placebo, bergamot odor, and peppermint odor groups. Adhesive strips were placed under the noses of all participants, with participants in the latter two groups having strips containing essential oils. The placebo group had a strip with no odor. After establishing a maximal voluntary contraction level, participants performed at 30% of their maximum for as long as they could tolerate, during which they provided ratings of perceived exertion (RPE) at 30 second intervals. Task-specific self-efficacy and Pleasantness were evaluated post-task. Results: One-way ANOVA analyses failed to reveal significant differences among the groups on session RPE, total grip time, and grip time up to and after RPE. Statistical differences were found between placebo and essential oil groups regarding task pleasantness. The placebo group reported higher pleasantness scores than essential oil groups. Conclusion: Although nonsignificant, findings suggest that bergamot essential oil may provide a more pleasant exercise experience than peppermint essential oil. This work expands the knowledge on the relationships between essential oils.

Despite the large number of studies on the multisensory aspects of tactile perception, very little is known regarding the effects of visual and auditory sensory modalities on the tactile hedonic evaluation of textures, especially when the presentation of the stimuli is mediated by a haptic device. In this study, different haptic virtual surfaces were rendered by varying the static and dynamic frictional coefficients of a Geomagic Touch device. In Experiment 1, the haptic surfaces were paired with pictures representing everyday materials (glass, plastic, rubber and steel); in Experiment 2, the haptic surfaces were paired with sounds resulting from the haptic exploration of paper or sandpaper. In both the experiments, participants were required to rate the pleasantness and the roughness of the virtual surfaces explored. Exploration times were also recorded. Both pleasantness and roughness judgments, as well as the durations of exploration, varied as a function of the combinations of the visuo-tactile and the audio-tactile stimuli presented. Taken together, these results suggest that vision and audition modulate haptic perception and hedonic preferences when tactile sensations are provided through a haptic device. Importantly, these results offer interesting suggestions for designing more pleasant, and even more realistic, multisensory virtual surfaces. 041b061a72