The sound of arousal in music is context-dependent

Humans, and many non-human animals, produce and respond to harsh, unpredictable, nonlinear sounds when alarmed, possibly because these are produced when acoustic production systems (vocal cords and syrinxes) are overblown in stressful, dangerous situations. Humans can simulate nonlinearities in music and soundtracks through the use of technological manipulations. Recent work found that film soundtracks from different genres differentially contain such sounds. We designed two experiments to determine specifically how simulated nonlinearities in soundtracks influence perceptions of arousal and valence. Subjects were presented with emotionally neutral musical exemplars that had neither noise nor abrupt frequency transitions, or versions of these musical exemplars that had noise or abrupt frequency upshifts or downshifts experimentally added. In a second experiment, these acoustic exemplars were paired with benign videos. Judgements of both arousal and valence were altered by the addition of these simulated nonlinearities in the first, music-only, experiment. In the second, multi-modal, experiment, valence (but not arousal) decreased with the addition of noise or frequency downshifts. Thus, the presence of a video image suppressed the ability of simulated nonlinearities to modify arousal. This is the first study examining how nonlinear simulations in music affect emotional judgements. These results demonstrate that the perception of potentially fearful or arousing sounds is influenced by the perceptual context and that the addition of a visual modality can antagonistically suppress the response to an acoustic stimulus.     

Acupuncture analgesia: an experimental investigation.

A study was designed to establish whether acupuncture has any analgesic properties beyond those of suggestion. In three one-hour experimental sessions the increases in detection thresholds and tolerances for thermal pain at six body locations on 12 subjects were compared. A control session (without needles) was followed by one session in which electrically stimulated needles were inserted in accord with Chinese practice, and another in which the needles were inserted to avoid all recognised acupuncture "points." Acupuncture was significantly more effective than suggestion in raising overall body pain thresholds but just below significance for tolerances. A significant disproportionate effect on the epigastrium, predicted by the choice of acupuncture points, was found for tolerances but not thresholds.     

Bacterial growth on lactose: an experimental investigation

A wild-type strain of Klebsiella oxytoca growing aerobically in batch culture has exhibited intermittent or oscillatory growth while growing on lactose at concentrations on the order of 1 g/L or less. In two-substrate experiments, preferred growth on glucose followed by growth on lactose also produced oscillatory growth behavior during the lactose growth phase at lactose concentrations of 1 g/L or less. Only oscillations in cell density have currently been observed. Alkalinization of the medium during growth on lactose indicated the presence of lactose active transport. The observed intermittent growth was reduced or removed during growth on lactose after preferred growth on galactose or in a medium containing 50 mM NaCl. Results suggested that the presence of an intracellular energy source or a sufficient DeltapH buffer may alleviate growth inhibition when transport and growth processes compete for essential energy resources during growth on lactose.     

Concentrations of NaCl and sucrose: equality in perceived taste intensity

Results from previous studies suggest that sucrose and NaClsolutions have an equal perceived taste intensity when the molarconcentration of sucrose is 1.5–1.75 times the molar concentrationof NaCl. However, according to other studies, sucrose and NaClsolutions taste equally strong when their molar concentrationsare about equal. This issue was further pursued using the methodof constant stimuli, where subjects matched the perceived tasteintensity of NaCl solutions to five sucrose references and viceversa. The results concur with previous findings that sucroseand NaCl solutions have equal perceived taste intensities whenthe molar concentration of sucrose is 1.5–1.75 times themolar concentration of NaCl.     

Social learning and the replication process: an experimental investigation

Human cultural traits typically result from a gradual process that has been described as analogous to biological evolution. This observation has led pioneering scholars to draw inspiration from population genetics to develop a rigorous and successful theoretical framework of cultural evolution. Social learning, the mechanism allowing information to be transmitted between individuals, has thus been described as a simple replication mechanism. Although useful, the extent to which this idealization appropriately describes the actual social learning events has not been carefully assessed. Here, we used a specifically developed computer task to evaluate (i) the extent to which social learning leads to the replication of an observed behaviour and (ii) the consequences it has for fitness landscape exploration. Our results show that social learning does not lead to a dichotomous choice between disregarding and replicating social information. Rather, it appeared that individuals combine and transform information coming from multiple sources to produce new solutions. As a consequence, landscape exploration was promoted by the use of social information. These results invite us to rethink the way social learning is commonly modelled and could question the validity of predictions coming from models considering this process as replicative.     

The perceived intensity of caffeine aftertaste: tasters versus nontasters

The length and intensity of the aftertaste of caffeine was measured in groups of tasters and nontasters in order to determine if any differential information could be provided by aftertaste perception. Results indicate that a period of 4 min is sufficient to see differences between tasters and nontasters, and that nontasters' aftertaste of the saturated solution is equal in intensity with tasters perception immediately after stimulus presentation, but then after approximately 1 min fade faster. Nontaster ratings for the weaker solution were lower throughout the entire time period.     

Influence of caffeine ingestion on perceived mood states, concentration, and arousal levels during a 75-min university lecture

This investigation aimed to assess the effect of a caffeine supplement on perceived mood state, concentration, and arousal during a 75-min university lecture. Methods. This randomized, blind, cross-over design investigation ran over a course of 2 consecutive weeks. During week 1, 10 third-year Human Movement and Exercise Science students were assigned to either a caffeine- or placebo-supplemented group and were subsequently required to attend a 75-min exercise rehabilitation lecture. Seven days later, students were assigned to the opposite supplementation group before attending a second follow-on lecture, equal in duration to that of week 1. At the conclusion of each lecture, students were required to complete a mood perception questionnaire to assess the perceived level of mood state, concentration, and arousal during the lecture. The results showed that after caffeine consumption, students perceived themselves to be significantly more awake, clear minded, energetic, alert, and anxious (P < 0.05). Additionally, students also felt they were better able to concentrate and had a greater level of arousal than when the placebo was consumed (P < 0.05). In conclusion, the results of this investigation show that university students report enhanced perceptual feelings of behavior and mood state when a low dose of caffeine is consumed 60 min prior to a 75-min academic lecture.     

Oral chemical irritation: does it reduce perceived taste intensity?

In an experiment in which capsaicin was presented in physicalmixture with taste stimuli, no reduction in perceived tasteintensity, relative to the control condition, was observed.This result is inconsistent with previous reports of taste intensityreductions when oral chemical irritants were only periodicallyinterspersed among taste stimuli (Lawless et al., 1985; Lawlessand Stevens, 1984). A second experiment directly compared thetwo presentation formats and their respective control conditionsin a repeated-measures design. The results of that test confirmthat greater apparent reductions in taste intensity are observedwhen the oral irritant is presented as a periodic rinse eventhough perceived irritation under rinse conditions regularlyfalls to levels significantly below those maintained with mixturepresentations. This observation indicates that much of the apparentmasking of taste intensity in the presence of oral irritationis not directly related to irritation level but is sensitiveto procedural variation.     

Detectability and perceived intensity for formaldehyde in smokers and non-smokers

Formaldehyde emanating from cigarette smoke and emissions frombuilding materials is an important contaminant of indoor airand an interesting gaseous compound in the study of smokers'sensitivity to odor. With the aid of hood exposures to 18 formaldehydeconcentrations (7.5 to 1000 ppb), odor detection thresholds(method of constant stimuli) and perceived odor intensities(method of magnitude estimation) were determined among heavycigarette smokers (22 women) and non-smokers (22 aged-matchedwomen). To adjust for individual differences in response behavior,the odor thresholds were corrected for false alarms resultingfrom purified air presentations and the scale values of odorintensity were calibrated according to the master scale principleusing loudness of pink noise as a reference scale [42 to 96dB(A)]. The results showed significantly higher odor detectionthresholds for smokers than for non-smokers, 94 and 55 ppb,respectively, and significantly lower odor intensities reportedby smokers than non-smokers. In evaluating the observers' audiograms,the smokers displayed significantly higher thresholds of hearingthan the non-smokers. The results support the possibility thathabitual cigarette smoking may result in decreased sensitivityof sensory systems in general.