PubMed Health⌕ Search

Biomedical subjects

D Broadbent

Publications and source records attributed to D Broadbent.

7 recordsLinked to original sources
PubMed1991

Implicit and explicit knowledge bases in artificial grammar learning.

Two experiments examined the claim for distinct implicit and explicit learning modes in the artificial grammar-learning task (Reber, 1967, 1989). Subjects initially attempted to memorize strings of letters generated by a finite-state grammar and then classified new grammatical and nongrammatical strings. Experiment 1 showed that subjects' assessment of isolated parts of strings was sufficient to account for their classification performance but that the rules elicited in free report were not sufficient. Experiment 2 showed that performing a concurrent random number generation task under different priorities interfered with free report and classification performance equally. Furthermore, giving different groups of subjects incidental or intentional learning instructions did not affect classification or free report.

Adult↗
PubMed1991

Effects of induced elated and depressed mood on self-focused attention.

Recent accounts of depression propose a central role for increased self-focus in the onset and maintenance of depression. The present study investigated whether there might also be a converse effect of depressed mood increasing self-focus. A state measure of self-focused attention was administered to normal subjects before and after induction of depressed or happy mood. Compared to happy subjects, depressed subjects showed more negative and less positive self-focus. Positive and negative external focus were unaffected by mood. A reciprocally reinforcing relationship between depressed mood and negative self-focus may be important in onset and maintenance of depression.

Adult↗
PubMed1990

Human attention: the exclusion of distracting information as a function of real and apparent separation of relevant and irrelevant events.

A leading theory suggests that human vision operates by separate and parallel analysis of each of the simple features of the visual scene; but computation of the identity of objects, which needs combination of these features, is undertaken selectively and only for some parts of the incoming information. It is known that the identity of distracting events affects reaction time only for distractors spatially close to the reaction signal. This suggests that the selection is spatially based; perhaps taking place in the projection areas. Experiments on this topic have, however, normally considered events only at a fixed viewing distance; in this study different viewing distances were employed. It was found that, over the range of conditions used, the ability to exclude irrelevant distractors depended upon the true physical separation and not on the angular separation at the eye of the observer. Hence the 'attention' system must operate at a point later than the computation of true physical location, rather than at the very early stage where angular separation only is available.

Attention↗
PubMed1987

Selective effect of lithium on cognitive performance in man.

The effects of lithium on psychomotor performance were examined in six healthy male volunteers (aged 26-31 years) and compared with those of a similar control population. Three computerised psychomotor tests (serial reaction time, semantic reasoning and syntatic reasoning) were administered before lithium, after 5 and 22 days of lithium carbonate (800 mg/d) and 4 days and 1 month after stopping the lithium. The only significant effect was an impairment of semantic reasoning during the chronic (22 day) test. This suggests a selective effect of lithium on associative mental tasks and may explain the subjects' experience of slowing in recall of object names whilst taking lithium.

Adult↗
PubMed1986

Performance effects of diazepam during and after prolonged administration.

Seven volunteers received diazepam for a 3-week period, maximum dose rate 25 mg per day, and were tested on a variety of functions before, at two points during, and at two points after the period. Their performance was compared with that of 8 controls and was inferior on a number of measures. There was no indication either of habituation or of potentiation of the effects as the period continued. Equally, the low performance persisted for some time after administration ceased, although performance was on the whole better than during the experimental period. The particular measures showing deterioration suggested that the effects are similar to those of barbiturates as opposed to those of, for example, chlorpromazine.

Adult↗
PubMed1986

Encoding speed of visual features and the occurrence of illusory conjunctions.

Earlier studies have found that people show characteristic errors when asked to observe a rapid stream of events and to name the colour of a certain letter, or the letter in a certain colour. They tend to report the letter or colour from an event later in time than the correct one. This is not true, however, if they are asked to name the colour of a digit amongst letters, without knowing in advance the identity of the digit. There is also some evidence that the errors are symmetric if the location of the target is not known in advance. Three experiments are reported which show that this symmetry results from slow encoding of the colour as compared with the digit. It is still true that uncertainty about target identity does reduce the tendency to see the target in a later than an earlier colour. This effect is, however, superimposed on asymmetries resulting from coding speed, and the effect of uncertainty of location may be due only to this.

Color Perception↗