This article reviews and evaluates the effectiveness of interventions aiming to encourage households to reduce energy consumption. Thirty-eight studies performed within the field of (applied) social and environmental psychology are reviewed, and categorized as involving either antecedent strategies (i.e. commitment, goal setting, information, modeling) or consequence strategies (i.e. feedback, rewards). Particular attention is given to the following evaluation criteria: ( 1) to what extent did the intervention result in behavioral changes and/or reductions in energy use, (2) were underlying behavioral determinants examined (e.g. knowledge, attitudes), ( 3) to what extent could effects be attributed to the interventions and, (4) were effects maintained over longer periods of time? Interestingly, most studies focus on voluntary behavior change, by changing individual knowledge and/or perceptions rather than changing contextual factors (i.e. pay-off structure) which may determine households' behavioral decisions. Interventions have been employed with varying degrees of success. Information tends to result in higher knowledge levels, but not necessarily in behavioral changes or energy savings. Rewards have effectively encouraged energy conservation, but with rather short-lived effects. Feedback has also proven its merits, in particular when given frequently. Some important issues cloud these conclusions, such as methodological problems. Also, little attention is given to actual environmental impact of energy savings. Often, an intervention's effectiveness is studied without examining underlying psychological determinants of energy use and energy savings. Also, it is not always clear whether effects were maintained over a longer period of time. Recommendations are given to further improve intervention planning and to enhance the effectiveness of interventions.

In this multidisciplinary study, an Internet-based tool was used to encourage households (N ¼ 189) to reduce their direct (gas, electricity and fuel) and indirect energy use (embedded in the production, transportation and disposal of consumer goods). A combination of tailored information, goal setting (5%), and tailored feedback was used. The purpose of this study was to examine whether this combination of interventions would result in (i) changes in direct and indirect energy use, (ii) changes in energy-related behaviors, and (iii) changes in behavioral antecedents (i.e. knowledge). After 5 months, households exposed to the combination of interventions saved 5.1%, while households in the control group used 0.7% more energy. Households exposed to the interventions saved significantly more direct energy than households in the control group did. No difference in indirect energy savings emerged. Households exposed to the interventions adopted a number of energy-saving behaviors during the course of the study, whereas households in the control group did so to a lesser extent. Households exposed to the interventions had significantly higher knowledge levels of energy conservation than the control group had. It is argued that if the aim is to effectively encourage household energy conservation, it is necessary to examine changes in energy use, energy-related behaviors and behavioral antecedents.

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A simulated driving task that required the simultaneous execution of two continuous visual tasks was administered to 12 healthy young (mean age 26.1 years) and 12 healthy older (mean age 64.4 years) experienced and currently active drivers. The first task was a compensatory lane-tracking task involving a three-dimensional road display. The second task was a timed, self-paced visual analysis task involving either a vocal or manual binary response to dot patterns projected within the road display. Using adaptive tasks, single-task difficulty was individually adjusted for each subject. To control for individual differences in attention allocation strategy, the dual task was performed according to three different sets of instructions based on the relative importance of each task. Compared with young adults, older adults showed a significantly decreased ability to divide attention. This effect was apparent in lane tracking and in the accuracy of visual analysis. The impairment of divided attention was less pronounced in the vocal condition than in the manual one. This suggests that difficulty in integrating responses may be an important determinant of poor dual-task performance in old age.

When drivers perform additional tasks while driving, research shows conflicting results: primary driving performance may deteriorate but adaptive changes such as reducing driving speed have also been noted. We hypothesized that the nature of the secondary task may be important: drivers may give more priority to tasks that serve goals of the driving task itself, for example route finding, than tasks not directly relevant for driving, for example tuning the radio. The main objective of the present driving simulator study was to test this hypothesis. Twenty subjects performed two different subsidiary tasks while driving through two levels of traffic density: a working memory (WM) task and a map reading (MAP) task. It was hypothesized that in high task demand situations, the WM task, irrelevant for the driving task, would be neglected more than the MAP task. The results confirmed the hypothesis: in MAP conditions, the WM task was indeed neglected, but map reading resulted in more swerving, indicating that the subjects looked at the map despite the high task demands. It is concluded that drivers will be highly motivated to get route information, and RG systems should therefore present their information in a readily understandable format.