Demonstration of the scalar property of timing with possums (Trichosurus vulpecula).

Many diverse species have demonstrated interval timing, the ability to respond appropriately to time in the range of seconds to minutes, suggesting that an ability to time is adaptive. The peak procedure is a common method of studying interval time perception. In the peak procedure, animals experience a mix of fixed-interval (FI) and extinction (EXT) trials. On EXT trials, responding typically increases to a peak at the time the FI schedule would normally deliver reinforcers before decreasing. Responding on different FI schedules within the peak procedure has been found to conform to Weber's law, whereby response variability is proportional to the length of the fixed interval. We conducted possibly the first investigation of the timing abilities of a marsupial common to Australia and New Zealand, the brushtail possum (Trichosurus vulpecula), using FI 15-, 30-, and 60-s schedules of reinforcement in the peak procedure. Response rates on EXT trials peaked at the time of usual reinforcer delivery, decreasing at longer time intervals, and were well fit by 3-parameter Gaussian curves, demonstrating the ability of possums to respond to time-based stimuli. Coefficients of variation suggested that the ability of possums to time was less accurate than that of mammals, but similar to that of birds, invertebrates, and reptiles. Coefficients of variation did not differ consistently over increasing FI intervals, showing that timing responses of possums likely conforms to the scalar property of timing also shown by other species. (PsycINFO Database Recor

Drug Contamination of U.S. Paper Currency and Forensic Relevance of Canine Alert to Paper Currency: A Critical Review of the Scientific Literature

Several studies have reported on wide-spread contamination of U.S. paper currency with cocaine and to a lesser extent other illicit drugs. Canines are trained and employed to search for and alert to drugs. Canine alert to currency has been used as evidence that currency has been directly involved in illicit drug trafficking to justify currency seizure and forfeiture. This assertion, particularly when the only evidence is based upon canine alert, has been challenged in the courts considering that most currency in circulation is contaminated with cocaine. Comprehensive review of the scientific literature establishes that (i) 67-100% of circulated U.S. currency is contaminated with cocaine ranging from a few nanograms to over one milligram/bill (ii) various biological and environmental parameters impact canine alert to drugs. It is concluded that canine alert to U.S. currency is not sufficiently reliable to determine that currency was directly used in an illicit drug transaction

Are our beaches safe? Quantifying the human health impact of anthropogenic beach litter on people in New Zealand

The environmental, social and cultural importance of beaches permeates human society, yet the risk of human injury associated with increasing exposure to anthropogenic beach litter remains an unknown. While the impact of marine debris and beach litter on marine and coastal fauna and flora is a widely reported global issue, we investigate the impact on human health in New Zealand. Anthropogenic beach litter is ubiquitous, few beaches remain pristine, which consequently influences tourist choices and potentially negatively interacts with humans. Human impacts are not well-investigated, with no quantitative studies of impact but many studies qualitatively inferring impact. New Zealand has a socialised medical system allowing a quantitative, decadal assessment of medical insurance claims to determine patterns and trends across ecosystems and causes. We demonstrate for the first time that anthropogenic beach litter poses a common and pervasive exposure hazard to all ages, with specific risk posed to young children. The New Zealand system allows these hazards to be investigated to determine the true effects and costs across a nation, providing an evidence base for decision-makers to address this ubiquitous environmental issue

Hyperbolic Discounting with Environmental Outcomes across Time, Space, and Probability

Environmental discounting is a potentially important research area for climate change mitigation. We aimed to replicate and extend earlier work on the discounting of a negative environmental outcome. We measured ratings of concern, and willingness to act to mitigate, an outcome involving air pollution that would hypothetically affect the garden and drinking water of the participants over psychological distance represented by temporal (1 month, 6 months, and 1, 3, 5, 10, and 80 years), spatial (5, 20, 50, 100, 1000, and 5000 km), and probabilistic (95%, 90%, 50%, 30%, 10%, and 5% likelihood) dimensions. For our data from 224 first-year psychology students, of four potential models (an exponential, simple hyperbolic, and two hyperboloid functions), the Rachlin hyperboloid was the best-fitting model describing ratings of concern and action across all three dimensions. Willingness to act was discounted more steeply than concern across all dimensions. There was little difference in discounting for outcomes described as human-caused rather than natural, except that willingness to act was discounted more steeply than concern for human-caused environmental outcomes compared to natural outcomes across spatial (and, less conclusively, temporal) distance. Presenting values of the three dimensions in random or progressive order had little effect on the results. Our results reflect the often-reported attitudebehavior gap whereby people maintain concern about a negative event over dimensions of psychological distance, but their willingness to act to mitigate the event is lower and more steeply discounted