SCALING VELOCITY AND SPACE FROM TIME ESTIMATES

A model described by the relation, relative estimated time = (subjective space)/(subjective velocity), is applied on time estimates collected in three experiments with moving spots indicating the time intervals which were estimated. The model is found to account satisfactorily for the data, thus permitting derivations of subjective scales of velocity and space.     

Individual postdecision processes in group settings

In two experiments Differentiation and Consolidation Theory (Diff Con) (Svenson, 1992) was used to investigate individual postdecision making processes in three-member groups. It was predicted that in groups in which the subjects preferred different alternatives (conflict groups), subjects would consolidate their own preferred alternative, and not the group's final decision. A second hypothesis was that no consolidation would be indicated in groups in which all members preferred the same alternative (non-conflict groups). The results showed that in conflict groups, the members who gave up their preferred alternative (minority members) consolidated their own preference, thereby significantly regretting the group decision. In contrast, members who got their own will through in the majority decision (majority members) showed no consolidation of the group decision. The corresponding pattern of results was replicated in a second experiment, using a different decision situation. The results indicated that perceptions of social support, agreement in a group and decreasing responsibility for a group's decision, could all partly substitute consolidation by attractiveness restructuring.     

Postdecision consolidation in a trend prediction task

To be able to learn from experience it is necessary to correctly apprehend experienced feedback and the situation in which it is provided. The results indicate how post-decision consolidation in complex domains may affect learning. The problem may be particularly pertinent in recurrent decision making where considerable risk is involved. The study explores the changes in aspect (signal) importance from pre- to postdiction as a function of outcome information. By postdiction we mean the remembering of an earlier prediction (cf. Hawkins & Hastie, 1990). Subjects were asked to decide on which of four alternative future price developments would follow a historical price trajectory for different commodities, and to rate the importance of each of the chosen alternative's corresponding aspects. The subjects revealed a bias in their support ratings of aspects--seeing support in aspects that traditionally (by themselves and in many contexts) would be seen as neutral or even counter-indicative of the alternative chosen. After an intermission, the subjects were also given information about what was indicated to be the actual development of the market. One group was told that their decisions were correct (irrespective of what the decisions were), another group that they were incorrect but close, a third group that they were incorrect by far, while a fourth group served as a control. Following this information the subjects were again asked to judge the importance of the aspects for their own prior decision on the most likely future development. The results indicated that outcome feed-back had an effect on post decision restructuring of facts. Subjects in the correct condition showed an average consolidation that increased the support, while the wrong conditions lead to negative consolidation (in retrospect indicating that they never found as much support for their decision in the past as they actually did). Thus, in a choice between consolidating their own initial prediction and the price trajectory they would have to live with, the decision makers consolidated the outcome. Therefore, the results of the study were related to the hindsight bias phenomenon (Fischhoff, 1975) and to Kahneman and Miller's (1986) mutability concept.     

Judgments of mean speed and predictions of route choice

How are driving speeds integrated when speeds vary along a route? In a first study, we examined heuristic processes used in judgments of mean speed when the mean speeds on parts of the trip varied. The judgments deviated systematically from objective mean speeds because the distances driven at different speeds were given more weight than travel time spent on the different distances. The second study showed that when there was a 10–15 min pause during a travel the effect on the mean speed decrease was underestimated for driving speeds of 90 km/h and higher. In the third study, the objective mean speeds and the subjective biased mean speed judgments were used to predict choices between routes with different speed limits. The results showed that subjective judgments predicted decisions to maximize mean speed significantly better than objective mean speeds. Finally, some applied and basic research implications of the results were discussed.     

Value conflict and post-decision consolidation

The primary goal of the present study was to investigate how the mental representations of value conflicts are restructured after a decision. A value conflict exists if a chosen alternative is less attractive than a non-chosen alternative on one important attribute when a decision is made. In order to follow up earlier field studies with no experimental control over value conflicts, the present study induced value conflicts in the laboratory. This was done through associating the more attractive of two alternatives with a smaller probability of success. The first hypothesis was that consolidation of value conflict attributes should follow the same pattern when the conflict is controlled experimentally as in earlier studies of real-life decisions. The second hypothesis was that consolidation should be weaker in a non-consequential laboratory study than in the earlier real-life studies. The third hypothesis was that stronger value conflicts (that is, value conflict on more important attributes) lead to greater consolidation effects than weaker value conflicts. The results showed that participants consolidated the value conflicts in the same way as in real-life decisions with the difference that also less important attributes were consolidated in the present study. However, the consolidation effects were not so strong that they caused advantage reversals on a conflict attribute, as in the earlier field studies with real outcomes and consequences. There was no relationship between strength of conflict and consolidation. The fact that no advantage reversals were registered leads to questions about the ecological validity of laboratory studies of non-consequential decision making.     

Errors in subtractions: judged and observed frequencies

In a first study 10 adults, aged 24-44 years, solved all 105 subtraction problems in the form M - N = , where 0 < or = M < or = 13, 0 < or = N < or = 13 and N < or = M. Each participant solved every problem 10 times and in total there were 10 500 answers. Answers, response latencies and errors were registered. Retrospective verbal reports were also given, indicating how a solution was reached: (1) via a (conscious) reconstructive cognitive process or (2) via an (unconscious) reproductive (retrieval) process. The participants made 291 errors (2.8%) when solving the subtractions in study 1. The rate of self-correction was very high, 92%. In a second study 27 undergraduate students estimated overall error rates, including self-corrected errors for the 105 subtraction problems used in the first study. Judged and actual error rates were compared. The participants systematically underestimated error rates for error prone problems and overestimated error rates for error free problems. The participants were fairly accurate when they predicted problems that were most error prone, with a hit rate of 0.67 for the (18) problems predicted as the most error prone ones. In contrast, predictions of which problems were error free were very poor with a hit rate of only 0.20 of the problems predicted as error free really having no errors in study 1. The correlation between judged error rates and frequencies for actually made errors was 0.69 for answers belonging to reconstructive solutions. In contrast, there was no significant correlation between judged and actual error rates at all for retrieved solutions, possibly reflecting the inaccessibility to consciousness of quick retrieval processes.     

Memories of real-life decisions

Three studies investigated decision makers' memory representations of choice alternatives in most important real-life decisions. In Study 1, each participant recalled the most important decision that she or he had ever made and rated to what degree a number of characteristics could describe the decisions. In Study 2, the participants were asked to think about an important decision that they had made during the last 7-10 days. In Study 3, the memory representations of decisions of a group of action-oriented participants were compared with those of a group of state-oriented participants (Kuhl, 1983). Characteristics related to standard decision theory, like consequences, values, and likelihood, had high ratings of applicability as well as affect/feeling. When testing the applicability of a circumplex model, the fuzzy-trace theory of memory, and differences between state- and action-oriented decision makers, we found (1) that there was no support for the circumplex model of emotions. Instead, an important decision problem was characterised by both positive and negative affect/emotion and thus, a bipolar mapping was found inadequate; (2) that a comparison of abstract and concrete aspects showed that the abstract characteristics scored higher, thereby supporting the fuzzy-trace theory; and (3) that the prediction that action-oriented participants would score higher than state-oriented participants on the characteristic of activity was not supported. However, state-oriented decision makers rated passivity higher than action-oriented decision makers for the important decision of leaving a partner. State-oriented decision makers used perceptual/cognitive scenario representations to a greater extent than action-oriented participants. Finally, it was stressed that in the development of decision theories it is essential to find theoretical representations as close as possible to how decision makers themselves represent the decisions. The method used in this contribution is focused on the role of memory in decision making and gives further insights into how important real-life decisions are represented by different decision makers.     

Decisions among time saving options: when intuition is strong and wrong

When people judge the time that can be saved by increasing the speed of an activity, they are often victims of a time saving bias. That is, they overestimate the time that can be saved by increasing the speed. Judgments of time savings following speed increase when driving follow the Proportion heuristic [Svenson, O. (1970). A functional measurement approach to intuitive estimation as exemplified by estimated time savings. Journal of Experimental Psychology, 86, 204-210]. In a choice between time saving options, this heuristic simplifies to the Ratio rule. The first study tested this rule and found that the Ratio rule predicted incorrect decisions when planning to save traveling time in road traffic. The second study showed that the time saving bias was also present in planning of health care; to specify, in decisions about which one of two clinics to reorganize to save more of the doctors' time for personal contacts with patients. To further test the Ratio rule, Study 3 used a matching procedure in which two decision alternatives were made equal by the participants. The results supported the Ratio rule. Practical implications of the results are discussed including the Planning fallacy. In conclusion, the present set of studies have illustrated a time saving bias and provided evidence explaining why people make systematic errors when judging and deciding about time saved following a speed increase.