Two experiments were conducted in an attempt to determine the conditions under which shifts in the starting position of a linear positioning response influenced the reproduction of the end location of movements of various lengths. In Experiment 1, response bias (i.e., shift in constant error) was affected by the direction of the shift in starting position between presentation and recall. For short (20 cm) and medium (50 cm) length movements, this relationship was evident regardless of hand used (left or right), direction of the movement (left to right or right to left), and length of the retention interval (5 or 45 s). However, no relation between response bias and the direction of the starting position shifts was apparent for long (80 cm) movements. The results of Experiment 2 in which more movement lengths were used revealed a response bias that corresponded to shifts in starting position primarily during the first few reproductions of the two shortest movements (20 and 30 cm). However, no systematic bias was evident for any length movement after three reproduction attempts. Possible strategies used by subjects to reproduce the end location of movements of various lengths were discussed.

No abstract

The sawfly Cephalcia lariciphila (Wachtl) is a pest of larch (Larix spp.) that has recently become widespread in Britain. Before taking measures to control the sawfly the status of parasites in the infestations was investigated. The only insect parasite species found was the ichneumonid Olesicampe monticola (Hedwig), which is new to Britain. As this insect is taxonomically so poorly known it is redescribed from specimens collected in South Wales. The preliminary biological observations show O. monticola to be welladapted to its host and that it can significantly reduce an infestation.

The findings In this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.