The Clacton Spear: the last one hundred years

In 1911 an eminent amateur prehistorian pulled the broken end of a pointed wooden shaft from Palaeolithic-age sediments at a seaside town in Essex. This artefact, still the earliest worked wood to be discovered in the world, became known as the Clacton Spear. Over the past 100 years it has variously been interpreted as a projectile weapon, a stave, a digging stick, a snow probe, a lance, a game stake and a prod to ward off rival scavengers. These perspectives have followed academic fashions, as the popular views of early hominins have altered. Since discovery the Clacton spear has also been replicated twice, has undergone physical transformations due to preservation treatments, and has featured in two public exhibitions. Within this article the changing context of the spear, its parallels, and all previous conservation treatments and their impacts are assessed.© 2015 Royal Archaeological Institute. This is an Accepted Manuscript of an article published by Taylor & Francis in The Archaeological Journal on 3rd March 2015, available online: http://www.tandfonline.com/doi.org/10.1080/00665983.2015.1008839.The attached document is the author(’s’) final accepted/submitted version of the journal article. You are advised to consult the publisher’s version if you wish to cite from it

Continuous Progressive Ratio Schedules as an Assessment of the Effects of Amphetamine on Motivation

Animals appear to pass through a sequence of physiological/ psychological states following amphetamine administration (stimulant, depressant, and recovery states). The purpose of this research was to see if the presence of these states could be inferred from changes in performance on a progressive ratio schedule. On a progressive ratio schedule, the number of responses required to obtain reward is increased after each reward, and changes in progressive ratio breakpoint (the highest ratio the subject completes) have been used to assess the effects of treatments on motivation. Subjects were eight female Sprague-Dawley rats. Animals were trained in one of four operant conditioning stations to respond on a progressive ratio schedule for food reward. Once trained, animals were transferred to one of eight monitoring stations where they could be continuously housed and where they could initiate responding on a progressive ratio schedule at different times during the light-dark cycle. When the pattern of breakpoints across the light-dark cycle stabilized, animals were administered a dose of amphetamine, and breakpoints at different times in the light-dark cycle were again assessed. Compared to baseline, amphetamine caused a change in the pattern of breakpoints seen at different times in the light-dark cycle. The change in the pattern of breakpoints suggested that the animals were in different physiological/ psychological states at different times post amphetamine administration. Continuous progressive ratio schedules could be used to assess a wide variety of treatments on motivation