Gourdon, A. and Beck, S. R. (2011) Overcoming the framing effect when making decisions based on verbal probabilities: Having more time is helpful but not enough. In: Communication and Cognition 2011: Manipulation, persuasion and deception in language; 26 - 28 Jan 2011, Neuchatel, Switzerland. (Unpublished)

Abstract

Uncertain outcomes can be described by raw probabilities (e.g., There is 40% chance), but also by verbal probabilities (e.g., There is a chance, It is not absolutely certain). Beyond their probabilistic meaning verbal probabilities also have a directionality (Teigen & Brun, 1995), i.e. can be positive or negative. The directionality gives verbal probabilities a framing effect on decisions: when presented with the likelihood that a drug for a headache will work, people typically recommend other people taking this drug more often if the likelihood was given using a positive verbal probability (e.g., some possibility) than if it was given using a negative verbal probability (e.g., quite uncertain), despite both verbal probabilities being judged by other participants as having the same probabilistic meaning (Teigen & Brun, 1999). In this study we made the first investigation into the potential differences in processing directionality and probabilistic meaning that could explain the framing effect of the directionality. We will also examine the conditions potentially favourable to this effect. In experiment 1, nineteen participants chose between two outcomes described by verbal probabilities. In one third of the trials the probabilistic meaning was controlled and the directionality varied. In another third the directionality was controlled and the probabilistic meaning varied. In the last third, both dimensions were different, reinforcing each other (congruent trials; e.g., a positive verbal probability carrying a high probabilistic meaning) or contradicting each other (incongruent trials; e.g. a negative verbal probability carrying a high probabilistic meaning). When both dimensions differed, participants chose more quickly between congruent verbal probabilities than between incongruent verbal probabilities. When only one dimension (directionality or probabilistic meaning) varied, participants chose more quickly between positive verbal probabilities and between pairs of high probabilistic meaning than between negative verbal probabilities and between pairs of low probabilistic meaning. Participants were also more accurate (i.e. chose the verbal probability carrying the highest probabilistic meaning most often) when choosing between congruent verbal probabilities and between positive verbal probabilities than when choosing between incongruent verbal probabilities and between negative verbal probabilities. Finally when the probabilistic meaning was held constant, participants tended to choose the outcome with the positive verbal probability more often than chance. In experiment 2, twenty participants completed the same task under two time conditions (in counterbalanced order): in the limited time condition, they had to answer within five seconds; in the unlimited time condition, they could take as much time as they needed. We aimed here to replicate the results of experiment 1 and to investigate if the framing effect could be overcome when time pressure was removed. In both time conditions the same pattern as in experiment 1 was observed regarding accuracy and response time. However when the probabilistic meaning was held constant, we observed that the preference for the positive verbal probability was no longer observed given unlimited time. In both experiments and both time conditions we observed a longer response time in the incongruent and low conditions, i.e. if the probabilistic meaning was contradicted by the directionality and if it was inconsistent with the task goal (find some treasure). This signals that people do not consider independently the probabilistic meaning or the directionality and suggests that the framing effect of directionality cannot be explained by people considering only the directionality. Also, even when there was no time pressure, the framing effect was seen for incongruent verbal probabilities. However if they had the same probabilistic meaning the framing effect was not observed in the unlimited time condition. Therefore having more time to choose between two verbal probabilities helps to overcome the framing effect of directionality, but this is the case only in some conditions. We conclude that the framing effect of directionality does not result only from performance costs and we will present suggestions to explore the pragmatics factors which are favourable to this framing effect.

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