Total Amount Of Exposure Research Articles

Does valence contribute to the effects of dual tasking in aversive autobiographical memory? Some unexpected findings

Background and objectivesLab experiments show that engaging in a working memory task while recalling an aversive memory reduces emotionality and vividness of memories. Studies targeting lab induced negative memory with valenced secondary tasks show promise, but work is needed on autobiographical memories to make it more in line with the original dual tasking research and PTSD treatment in clinical populations. In this study, we address this gap by evaluating differential effectiveness of valenced dual tasks on emotionality and vividness of aversive autobiographical memories. MethodsUniversity students (N = 178) recalled an aversive autobiographical memory while rating either positive pictures, negative pictures, or while looking at a cross in the exposure only condition. Participants were randomized to one of three aforementioned conditions and rated their memories before and after each intervention on emotionality and vividness. ResultsAgainst expectations, memories became more emotional and vivid regardless of condition. With regard to vividness, this effect was characterized by an interaction effect: memories became more vivid in the exposure only condition than in the combined dual tasking conditions. All effect sizes were small. LimitationsWorking memory load in the dual tasking conditions might have been insufficient. ConclusionsThe current study did not extend findings with regard to (valenced) dual tasking and revealed a possible sensitization effect of script driven autobiographical memory induction. Our study highlights the importance of aspects such as the total amount of exposure and characteristics of memory induction, specifically the addition of a script driven approach to the usual self-initiated memory activation in dual tasking research.

Variations in occupational exposure to magnetic fields among welders in Malaysia

This study attempted to estimate the lifelong magnetic field (MF) exposures of a particular group of welders. Exposure was quantified via measurements, observations and interviews. It was found that these welders face a vast range of lifelong MF exposures depending on the welding processes and duration of the welding tasks performed. This may explain the inconsistency in the results of studies of MF exposures on human health. The mere assessing of the MF exposure levels through spot measurements does not give an overall picture of the total amount of exposure received by the welders as some of these workers performed the welding task throughout the day, whereas others performed this as a part of their job. The exposure to various chemicals in the fume may complicate the interpretation of the elevated health risk among the welders.

RISK ANALYSIS OF VOLATILE ORGANIC COMPOUNDS THROUGH DAILY LIFE CYCLE IN THE INDUSTRIAL CITY IN KOREA

This study analyzed the risk of exposure to volatile organic compounds (VOCs) through a study of activity patterns in the Korean industrial city, Ulsan. The daily life cycle patterns(LCPs) of 331 people in Ulsan were surveyed and the average LCPs in Ulsan were obtained by statistical analysis. Nine to twelve personal air samples of VOC exposure at the breathing zones were collected at each LCP. This included hours for sleeping,cooking and eating, going to and from work, working, participating in field or outdoor activities, reading, watchingTV, and shopping. The components and concentrations of the collected VOCs were identified by a Gas Chromatography-MassDetector (GC-MS). The overall reproducibility of all GC analytical procedures of the simultaneously collected duplicatesample pairs represented a mean of percent differences rangingfrom about 9 to 13%. For the general population of Ulsan, thecarcinogenic and non-carcinogenic risk of exposure to theVOCs during the LCPs was evaluated. The carcinogenic riskwas analyzed using both the chronic daily exposure orlifetime average daily exposure (CDI) and the cancerpotency factor. The non-carcinogenic risk was analyzedusing both the CDI and the chronic reference dose.The major chemical forms of the identified VOCs were oxidized forms (43%), aliphatic alkanes (29%) and aromatics (15%). Even though the highest total exposure strength per unit time of each activity was observed during shopping, the highest totalamount of exposure to VOCs was identified as the exposure duringwork. The total carcinogenic risk of exposure to the carcinogenicVOCs through daily life cycle in Ulsan was 2.0 × 10-4which is substantially exceeding the permissible carcinogenicrisk level, 10-5 ∼10-6. The carcinogenic riskduring most of the life cycle activities, except forreading, mainly performed indoors, was higher than that ofthe activities performed outdoors. The carcinogenic risk bybenzene exposure was about 56% (time weighted average) ofthe total carcinogenic risk by the exposure to thecarcinogenic VOCs. During cooking and eating, shopping andout door activities, however, the carcinogenic risk by theexposure to chlorinated compounds like chloroform exceededthe exposure to benzene. The overall hazard index (non-carcinogenic risk) by a chronic exposure to carcinogenicand non-carcinogenic VOCs through daily life cycle in Ulsanwas evaluated as 3.91 × 10-1, which is much less than1.0 considered as a hazard level to human health, and thusit seems likely not to produce a severe health hazard.

Perceptual learning in flavor aversion conditioning: Roles of stimulus comparison and latent inhibition of common stimulus elements

In three experiments, rats received training in which an aversion was established to one flavor and the extent to which this aversion generalized to a second flavor was tested. Experiment 1 showed that nonreinforced preexposure to both flavors resulted in reduced generalization between them. Experiments 2 and 3 demonstrated that this reduction in generalization required the two flavors to be presented on alternate trials during preexposure. Subjects given preexposure consisting of a block of trials with one flavor followed by a block of trials with the other showed the same degree of generalization as subjects given no preexposure. The two schedules of stimulus presentation were equated in the total amount of exposure given to each stimulus, making it unlikely that differences in latent inhibition could be responsible for the difference seen on the test. It is suggested that the opportunity for stimulus comparison offered by the alternating schedule might be important in a process of perceptual learning that is responsible for the reduced generalization.

The effects of compound in vivo and imaginal exposure: A test of fear enhancement models

Eysenck has hypothesized that extinction procedures, such as those used in flooding and implosive therapy, contain implicit aversive reinforcement contingencies which may increase conditioned fear. An alternative view has been proposed by Gordon and his colleagues, who suggest that memory reactivation is responsible for instances of increased fear responding. The present study was designed as a differential test of these proposals. Female students who demonstrated avoidance of a harmless snake were presented with in vivo exposure to the snake in an attempt to replicate previous demonstrations of fear enhancement. Imaginal exposure was added for half of the groups. The primary findings were: (1) a generally linear relationship between the total amount of exposure (whether in vivo and/or imaginal) and improvement in both behavioral approach to the fear stimulus and self-reports of fear; (2) greater physiological improvement associated with combined in vivo and imaginal exposure. Fear enhancement was not replicated and the results were not consistent with Eysenck's incubation model. Instead, the findings support two-factor avoidance theory and are compatible with Gordon's proposal. Additionally, a question is raised regarding the suitability of control procedures in existing between-groups demonstrations of fear enhancement.

Measurements of the energy spectrum of cosmic-ray muons at sea-level with emulsion chambers

The energy spectrum of cosmic-ray muons at sea-level has been measured in the energy range of 1 TeV to 10 TeV with the emulsion chambers exposed at shallow depth underground. The total amount of exposure is 61.6 tons of lead/year. On the vertical muon intensity, it is shown that the index of the spectrum is 2.70±0.10, when it is expressed with a single power law. The zenith angle distributions in the energies around several TeV are not inconsistent with those expected from the muons of pion and kaon decay.