The thermal decomposition of trisethylene diamine chromium(III) trichloride in an inert atmosphere has been shown to be catalysed by ammonium chloride but not by ammonium bromide or ammonium iodide as suggested by a previous worker. The details of sample presentation can effect the results and the presence of oxidising conditions may have influenced previous work.
The hunter-gatherer hypothesis of Silverman and Eals (1992) is the best-supported evolutionary explanation for sex differences in human spatial cognitive skills. It proposes that the sex differences in performance on a range of spatial task are a consequence of males (who hunted much more than did females) being better adapted to encode space allocentrically, and to rely on Euclidian navigational strategies employing distant landmarks, whereas females (who gathered much more than did males) are better adapted to encode space more egocentrically, navigating based more on local landmarks, and to be better able to precisely encode the position of particular objects. We tested this hypothesis by comparing the performance of male and female participants in a virtual navigation task (in which we could manipulate the landmark information available), a virtual dead-reckoning task and an object location memory task. The patterns of sex differences in the spatial tasks were strongly supportive of the hunter-gatherer hypothesis, but the sex-specific correlations between tasks thought to be underpinned by the same spatial-cognitive ability were not always supportive of the hypothesis, suggesting that the hunter-gatherer hypothesis requires some revisions or extensions.