Mental planning and the Tower of London task

The Tower of London (TOL) task has been used extensively as a test of planning ability in neuropsychological patients and normal populations. Participants are asked to preplan mentally a sequence of moves to match a start set of discs to a goal, and then to execute the moves one by one. The mental preplanning stage has been identified as critical to efficient performance. The current experiments examined whether manipulations of mental preplanning influence performance on the TOL. In Experiment 1, the effect of different planning instructions was examined. Those told to make full mental plans spent considerably longer in planning than participants given no specific planning instructions, yet there was no effect of instruction condition on the efficiency of executing plans. Experiment 2 investigated whether people were able to plan mentally, by looking at their ability to identify intermediate states of an optimum mental plan. Results indicated that most individuals could make accurate preplans up to two subgoals ahead, but not three. However, making an efficient preplan did not result in better subsequent execution of moves to solve the TOL trial. It is concluded that people can make effective mental plans for a limited number of moves. However, on the TOL task, mental preplanning does not offer benefits in terms of quicker performance, or more accurate solution. The nature of planning in the TOL task is therefore questioned.     

Sensitivity to the cognitive and affective qualities of odours

This study examined cognitive and emotional responses to odours in the laboratory in relation to everyday attitudes toward odours. A total of 136 subjects completed a questionnaire about the role of Odours in Everyday Life (OELQ) and their responses were summed to develop an index of overall responsiveness to odours: 36 subjects, who were in the top and bottom quartiles on this index, rated pleasant (e.g., rose) and unpleasant (e.g., synthetic sweat) odours in the laboratory on 7-point scales. Separate factor analyses were done for the OELQ items and the laboratory ratings, and these factors were intercorrelated. The factor analysis on the OELQ data yielded three primary factors, encompassing the Sexual Role of Bodily Odours, Ecological Odour Sensitivity, and Odour-evoked Memories, as well as three secondary factors. Two factors were derived from the laboratory ratings contrasting Cognitive (sensations, images, memories) and Affective (pleasant, soothing, energising) Responses. Correlations among the factors showed that Ecological Odour Sensitivity in everyday life was correlated with strong Cognitive but weak Affective Responsiveness to the laboratory odours. In contrast, the Sexual Role of Bodily Odours (OELQ) was positively correlated with Affective Responses to the odours in the laboratory. These data underscore the dual role of odours in stimulating cognitive and affective reactions both in everyday life and in the laboratory.