PubMed Health⌕ Search

Biomedical subjects

M P Dean

Publications and source records attributed to M P Dean.

4 recordsLinked to original sources
PubMed2001

Interference from related items in object identification.

Interference between related items in the identification of objects was examined using a postcue procedure. Pairs of objects were presented as differently colored line drawings followed by a color cue to indicate which object to name. Naming latencies were longer when both objects were from the same superordinate category than when they were unrelated. This interference effect was replicated when subjects were cued to report the color of a drawing rather than its name. Interference was greatly reduced when more distinctive attributes were used to distinguish members of a pair, both when the task required naming an object and when it required report of an object's attribute. These results challenge accounts of interference in the postcue paradigm that are based on competitive interactions in the activation of phonological representations by semantics and instead implicate object-attribute integration in memory as the source of interference.

Adult↗
PubMed2000

Reduction in 8-methoxypsoralen immersion time alters the erythemal response to bath PUVA.

Topical psoralen plus ultraviolet A (PUVA) using 8-methoxypsoralen (8-MOP) bath solution is a well established and effective treatment in dermatology. The standard immersion time in the UK is 15 min, but a shorter bathing period could potentially increase treatment convenience. In order to examine the effect of reduction in immersion time on skin phototoxicity, we compared the erythemal response to UVA following 5 min and 15 min psoralen baths. The study was performed on the forearm skin of 7 healthy volunteers using an 8-MOP psoralen concentration of 2.6 mg/l. One forearm of each volunteer was soaked for 15 min and the other for 5 min, followed by immediate irradiation with a series of 10 doses of broadband UVA ranging from 0.1 J/cm2 to 6.9 J/cm2. At 72 h, the minimal phototoxic doses (MPDs) were noted and erythema readings (erythema index) were taken in triplicate with a reflectance instrument. The median MPD following 5 min immersion was 1.7 (range 0.7-2.7) J/cm2 compared with 1.0 (range 0.4-1.7) J/cm2 after 15 min treatment, with no significant difference. However, the mean slope of erythema dose-response on the 15-min treated side was significantly steeper than on the 5-min treated side, 0.036 and 0.021 respectively, P < 0.05. Hence, this preliminary work shows that reducing 8-MOP immersion time to 5 min reduces the erythemal response to UVA. It will clearly be necessary to examine the effect of a shortened immersion period on disease clearance before considering such a change to the topical PUVA regime.

Adult↗
PubMed1996

Reinstatement of prior processing and repetition priming.

Two principal accounts of repetition priming describe either reinstatement of prior processing demands or activation of item-specific representations used in stimulus recognition as mechanisms by which the effect occurs. The former type of account predicts maximal priming when the same task is performed at first and second encounter (i.e. at training and test). The latter type of account predicts priming in any test task that requires access to item-specific representations as long as those items have been recognised earlier, regardless of the training task. An experiment was performed to test these contrasting predictions, in which subjects matched pairs of object pictures on the basis of either the colour of a segment of each object or on the basis of each object's identity. No repetition priming was observed when subjects performed colour matching at both first and second encounter. Priming was observed when responses were made on the basis of identity at both first and second encounter, and there was equivalent priming when colour matching was performed at the first encounter and identity matching at the second encounter. These results pose problems for theories of repetition priming based on reinstatement of prior processing demands, as colour matching did not prime subsequent colour matching (exact reinstatement of processing demands), whereas it did prime subsequent identity matching as much as did prior identity matching (a change in processing demands). These results are consistent with repetition priming occurring within a system that represents the identities of items.

Adult↗