Jason M. Tangen

A signal detection analysis of contingency data

There are many psychological tasks that involve the pairing of binary variables. The various tasks used often address different questions and are motivated by different theoretical issues and traditions. Upon closer examination, however, the tasks are remarkably similar in structure. In the present paper, we examine two such tasks, the contingency judgment task and the signal detection task, and we apply a signal detection analysis to contingency judgment data. We suggest that the signal detection analysis provides a novel interpretation of a well-established but poorly understood phenomenon of contingency judgments-the outcome-density effect.

Identifying Fingerprint Expertise

“CSI”-style TV shows give the impression that fingerprint identification is fully automated. In reality, when a fingerprint is found at a crime scene, it is a human examiner who is faced with the task of identifying the person who left the print—a task that falls squarely in the domain of psychology. The difficulty is that no properly controlled experiments have been conducted on fingerprint examiners’ accuracy in identifying perpetrators (Loftus & Cole, 2004), even though fingerprints have been used in criminal courts for more than 100 years. Examiners have even claimed to be infallible (Federal Bureau of Investigation, 1984). However, the U.S. National Academy of Sciences has recently condemned these claims as scientifically implausible, reporting that faulty analyses may be contributing to wrongful convictions of innocent people (National Research Council, Committee on Identifying the Needs of the Forensic Science Community, 2009). Proficiency tests of fingerprint examiners and previous studies of examiners’ performance have not adequately addressed the issue of accuracy, and they been heavily criticized for (among other things) failing to include large, counterbalanced samples of targets and distractors for which the ground truth is known (see Cole, 2008, and Vokey, Tangen, & Cole, 2009). Thus, it is not clear what these tests say about the proficiency of fingerprint examiners, if they say anything at all. Researchers at the National Academy of Sciences and elsewhere (e.g., Saks & Koehler, 2005; Spinney, 2010) have argued that there is an urgent need to develop objective measures of accuracy in fingerprint identification. Here we present such data.

Cue interaction and judgments of causality: Contributions of causal and associative processes

In four experiments, the predictions made by causal model theory and the Rescorla-Wagner model were tested by using a cue interaction paradigm that measures the relative response to a given event based on the influence or salience of an alternative event. Experiments 1 and 2 uncorrelated two variables that have typically been confounded in the literature (causal order and the number of cues and outcomes) and demonstrated that overall contingency judgments are influenced by the causal structure of the events. Experiment 3 showed that trial-by-trial prediction responses, a second measure of causal assessment, were not influenced by the causal structure of the described events. Experiment 4 revealed that participants became less sensitive to the influence of the causal structure in both their ratings and their predictions as trials progressed. Thus, two experiments provided evidence for highlevel (causal reasoning) processes, and two experiments provided evidence for low-level (associative) processes. We argue that both factors influence causal assessment, depending on what is being asked about the events and participants’ experience with those events.

Honeybees can discriminate between Monet and Picasso paintings

Honeybees (Apis mellifera) have remarkable visual learning and discrimination abilities that extend beyond learning simple colours, shapes or patterns. They can discriminate landscape scenes, types of flowers, and even human faces. This suggests that in spite of their small brain, honeybees have a highly developed capacity for processing complex visual information, comparable in many respects to vertebrates. Here, we investigated whether this capacity extends to complex images that humans distinguish on the basis of artistic style: Impressionist paintings by Monet and Cubist paintings by Picasso. We show that honeybees learned to simultaneously discriminate between five different Monet and Picasso paintings, and that they do not rely on luminance, colour, or spatial frequency information for discrimination. When presented with novel paintings of the same style, the bees even demonstrated some ability to generalize. This suggests that honeybees are able to discriminate Monet paintings from Picasso ones by extracting and learning the characteristic visual information inherent in each painting style. Our study further suggests that discrimination of artistic styles is not a higher cognitive function that is unique to humans, but simply due to the capacity of animals—from insects to humans—to extract and categorize the visual characteristics of complex images.

Expertise in Fingerprint Identification

Although fingerprint experts have presented evidence in criminal courts for more than a century, there have been few scientific investigations of the human capacity to discriminate these patterns. A recent latent print matching experiment shows that qualified, court‐practicing fingerprint experts are exceedingly accurate (and more conservative) compared with novices, but they do make errors. Here, a rationale for the design of this experiment is provided. We argue that fidelity, generalizability, and control must be balanced to answer important research questions; that the proficiency and competence of fingerprint examiners are best determined when experiments include highly similar print pairs, in a signal detection paradigm, where the ground truth is known; and that inferring from this experiment the statement “The error rate of fingerprint identification is 0.68%” would be unjustified. In closing, the ramifications of these findings for the future psychological study of forensic expertise and the implications for expert testimony and public policy are considered.

Is Perruchet's Dissociation Between Eyeblink Conditioned Responding and Outcome Expectancy Evidence for Two Learning Systems?

P. Perruchet (1985b) showed a double dissociation of conditioned responses (CRs) and expectancy for an airpuff unconditioned stimulus (US) in a 50% partial reinforcement schedule in human eyeblink conditioning. In the Perruchet effect, participants show an increase in CRs and a concurrent decrease in expectancy for the airpuff across runs of reinforced trials; conversely, participants show a decrease in CRs and a concurrent increase in expectancy for the airpuff across runs of nonreinforced trials. Three eyeblink conditioning experiments investigated whether the linear trend in eyeblink CRs in the Perruchet effect is a result of changes in associative strength of the conditioned stimulus (CS), US sensitization, or learning the precise timing of the US. Experiments 1 and 2 demonstrated that the linear trend in eyeblink CRs is not the result of US sensitization. Experiment 3 showed that the linear trend in eyeblink CRs is present with both a fixed and a variable CS-US interval and so is not the result of learning the precise timing of the US. The results are difficult to reconcile with a single learning process model of associative learning in which expectancy mediates CRs.

On the preliminary psychophysics of fingerprint identification

For a century, the matching of images of fingerprints has been used for forensic identification. Despite that history, there have been no published, peer-reviewed studies directly examining the extent to which people can correctly match fingerprints to one another. The results of three experiments using naïve undergraduates to match images of fingerprints are reported. The results demonstrate that people can identify fingerprints quite well, and that matching accuracy can vary as a function of both source finger type and image similarity.

Temporal contiguity and contingency judgments: A Pavlovian analogue

The two experiments reported examine the role of temporal contiguity on judgments of contingency in a human analogue of the Pavlovian task. The data show that the effect of the actual delay on contingency judgment depends on the observer’s expectation regarding the delay. for a fixed contingency between the cue and the outcome, ratings of the contingency are higher when the actual delay is congruent with the observer’s expectation than when it is incongruent. We argue that our data can be understood within the context of the temporal coding hypothesis.

The nature of expertise in fingerprint matching: Experts can do a lot with a little

Expert decision making often seems impressive, even miraculous. People with genuine expertise in a particular domain can perform quickly and accurately, and with little information. In the series of experiments presented here, we manipulate the amount of “information” available to a group of experts whose job it is to identify the source of crime scene fingerprints. In Experiment 1, we reduced the amount of information available to experts by inverting fingerprint pairs and adding visual noise. There was no evidence for an inversion effect—experts were just as accurate for inverted prints as they were for upright prints—but expert performance with artificially noisy prints was impressive. In Experiment 2, we separated matching and nonmatching print pairs in time. Experts were conservative, but they were still able to discriminate pairs of fingerprints that were separated by five-seconds, even though the task was quite different from their everyday experience. In Experiment 3, we separated the print pairs further in time to test the long-term memory of experts compared to novices. Long-term recognition memory for experts and novices was the same, with both performing around chance. In Experiment 4, we presented pairs of fingerprints quickly to experts and novices in a matching task. Experts were more accurate than novices, particularly for similar nonmatching pairs, and experts were generally more accurate when they had more time. It is clear that experts can match prints accurately when there is reduced visual information, reduced opportunity for direct comparison, and reduced time to engage in deliberate reasoning. These findings suggest that non-analytic processing accounts for a substantial portion of the variance in expert fingerprint matching accuracy. Our conclusion is at odds with general wisdom in fingerprint identification practice and formal training, and at odds with the claims and explanations that are offered in court during expert testimony.

The relative effect of cue interaction.

It is well established that two predictor cues (A and B) of a common outcome interact in that the judgement of the relationship between each cue and the outcome is influenced by the pairing history of the other cue with that outcome. For example, when the contingency of A with an outcome is weaker than the contingency of B with that outcome, the rating of the predictiveness of A is reduced relative to a situation where only A is paired with the outcome. One explanation of such cue interaction effects is provided by the conditional ΔP account. Spellman (1996b) derived a counterintuitive prediction of the conditional ΔP account where cue interaction should not occur under certain conditions even though a relatively poor predictor of an outcome is paired with a relatively good predictor of that outcome. However, Spellman (1996b) did not provide data to evaluate this prediction. In the present paper, we report the relevant data and show that they are consistent with the conditional ΔP account. A competing account of cue interaction is provided by the Rescorla-Wagner (RW) model. We derive the predictions of the RW model for the conditions specified by Spellman (1996b), and show that at asymptote the predictions of the RW model are identical to those of the conditional ΔP account.