ARQUETAS POZOS Y SUMIDEROS

Situations in which the bias is no longer present offer a window into studying the causal forces behind biased responding, and ultimately behind the decision- making process. In this chapter I will present four experiments. The first three experiments will test the challenges I issued against the HAM account in Chapter 2. They were (1) that the truth bias must be in part explained by the cognition of the rater independent of the behaviour of the speaker, (2) that the shift in bias over time must be the result of the amount of processing time available, and (3) that if it time cannot predict the change in bias, then the type of information available must. In the last experiment in this chapter will consider and show empirical support for an alternative account of the change in bias over time: raters are making use of a consistency heuristic.

Masip et al. (2006; Masip, Garrido, et al., 2009) noted that typical lie detection studies present brief snippets of behaviour, often no longer than 30 s in duration, which may be too short to give enough information to the rater and to give them sufficient processing time. In their study, they considered statements lasting over a period of minutes. To more closely simulate a police interview setup, each speaker was asked three questions about different aspects of the same mock crime scene they had just witnessed. They were instructed to either lie or tell the truth throughout their statement, meaning that each speaker produced either three deceptive or three truthful

responses as part of their statement. On presenting recordings of these interviews to a set of rater participants, an initial truth bias was found after the first response, but by the second and third response the truth bias showed a significant reduction and their accuracy increased. The authors interpreted these findings as evidence of a default- interventionist HAM, which predicts an initial default heuristic processing is interrupted over time by a more analytical, less biased and less error-prone form of processing (Masip et al., 2006; Masip, Garrido, et al., 2009; Masip et al., 2010).

Whilst the findings are consistent with a HAM, there are a number of challenges that must be met if a HAM account is to be accepted over other potential

explanations. First, the bias may be little more than an accurate reflection of the behaviour being rated (Fan et al., 1995; Zuckerman et al., 1987; Zuckerman, Koestner, et al., 1984). This challenge is taken up in Experiment 1. Evidence for an independent cognitive component to the truth bias will be shown.

Second, previous studies have only captured the judgment at the point of the first, second and third response of the statement. This offers a proxy for the amount of processing time, but because any given response can be long or short, it is not an accurate indication. Because both default-interventionist and parallel-competition models make a claim to the duration of processing time as the mediating factor between heuristic and analytical processing (Evans, 2007), it is necessary to more directly assess the effect of processing time on the truth bias. In Experiments 1 and 2, logistic mixed effects models will be constructed to test this prediction. Although the point of rating can predict the decline in truth bias, the duration of processing time as measured by the cumulative viewing duration up until the point of judgment cannot. This presents the first major challenge to the HAM.

If HAMs are to account for the truth bias, the switch between the two systems of thought cannot be determined by processing time because this was not supported in Experiment 1. Default-interventionist and parallel-competition class of models make this prediction (Evans, 2007), but a third and final class of models identified by Evans (2007), pre-emptive conflict resolution models, do not. Instead, they propose heuristic or analytical processing is chosen at the outset of the decision-making process. For the HAM to be supported, it must be shown that if processing time cannot account for the decline in the truth bias, the selection of heuristic or analytical processing at the outset of the judgment can instead. For example, the decline in the truth bias may be

attributable to a switch from the use of visual cues to verbal cues. Where only visual or only verbal cues are present, there should be observed no decline in the bias across the ratings; rather, visual cues should show a consistent truth bias and verbal cues should show consistently unbiased responding. However, Experiment 2 fails to find support for this account, showing a decline in the truth bias regardless of the channel (visual or verbal) available.

In Experiment 3, the processing time challenge is revisited. Thus far, the mixed effects models have been used to statistically demonstrate the lack of an effect. A more robust test of the processing time prediction would be to manipulate the

processing time. With shorter clips, there should be a lesser or no decline in the truth bias reflecting the continued use of heuristic processing, but with longer clips the decline in the truth bias should be observed as before. Consider also that the amount of processing time available ought be a useful cue as to whether to select heuristic or analytical processing from the outset, if a pre-emptive-conflict resolution model is true (Evans, 2007). However, in both conditions a declining truth bias is observed, again failing to support the HAM.

The decline in the truth bias can be observed across each new response, but it is not predicted by processing time. The presentation of each new response from the speaker may account for the decline in the truth bias. In Experiment 4, consideration is given to whether comparisons between the responses can account for the

phenomenon. Note that this differs from the behavioural account tested in Experiment 1 insofar as it is the perception of consistency that is important, not whether the speaker truly is or is not consistent. Raters disagree as to whether a given statement is consistent or not (Granhag & Strömwall, 1999). The declining bias could reflect this perception. Experiment 4 supports this explanation, although it is noteworthy that consistency was found to be a diagnostic indicator of deception also.