In sequential diagnostic reasoning, observed pieces of evidence activate hypotheses in memory and... more In sequential diagnostic reasoning, observed pieces of evidence activate hypotheses in memory and are integrated to reach a final diagnosis. The order of evidence can influence diagnostic reasoning. This article examines the processing of ambiguous evidence underlying order effects if multiple hypotheses are activated. In five experiments with a quasi-medical scenario, participants dealt with symptom sequences supporting multiple diagnoses. The symptom order, the response mode (end-of-sequence, step-by-step), and the consistency of evidence were manipulated. A primacy order effect occurred with both response modes suggesting that ambiguous pieces of evidence were distorted toward the hypothesis that strongly corresponded with the first piece. The primacy effect was partially counteracted by stepwise belief ratings, which strengthened the weight of recent evidence and promoted switching to an alternative diagnosis. We conclude that once hypotheses are generated, the interplay of coherence-oriented information distortion and memory-dependent analytic processes propagates into distinct order effects in diagnoses.
ABSTRACT In sequential diagnostic reasoning, observed evidence activates hypotheses about possibl... more ABSTRACT In sequential diagnostic reasoning, observed evidence activates hypotheses about possible causes in memory. These memory activations have been previously examined with a probe reaction task for problems with a single correct diagnosis. We applied this process tracing method to ambiguous problems with multiple compatible hypotheses. When participants reasoned about the causes of ambiguous symptom sequences, they were prompted to respond to probes representing hypotheses. The response time to a probe was shorter if the current support for the respective hypothesis was stronger indicating that the processing of compatible hypotheses can be traced. For sequences with two equally supported hypotheses, the initial hypothesis was more often chosen as the final diagnosis (a primacy effect). Probe reaction times suggest that the initial hypothesis has been activated more strongly already early, when it was finally chosen as the diagnosis. Nevertheless, substantial variance in response times limits the task's applicability for process tracing.
Transportation Research Part F: Traffic Psychology and Behaviour, 2005
Recent studies have explored a promising method to measure driver workload-the Peripheral Detecti... more Recent studies have explored a promising method to measure driver workload-the Peripheral Detection Task (PDT). The PDT has been suggested as a standard method to assess safety-relevant workload from the use of in-vehicle information systems (IVIS) while driving. This paper reports the German part of a Swedish-German cooperative study in which the PDT was investigated focusing on its specific sensitivity compared with alternative workload measures. Forty-nine professional drivers performed the PDT while following route guidance system instructions on an inner-city route. The route consisted of both highly demanding and less demanding sections. Two route guidance systems that differed mainly in display size and display organization were compared. Subjective workload ratings (NASA-TLX) as well as physiological measures (heart rate and heart rate variability) were collected as reference data. The PDT showed sensitivity to route demands. Despite their differing displays, both route guidance systems affected PDT performance similarly in intervals of several minutes. However, the PDT proved sensitive to peaks in workload from IVIS use and from the driving task. Peaks in workload were studied by video analyses of four selected subsections on the route. Subjective workload ratings reflected overall route demands and also did not indicate differing effects of the two displays. The physiological measures were less sensitive to workload and indicated emotional strain as well. An assessment of the PDT as a method for the measurement of safety-related workload is given.
The common methods for studying heuristics in memorybased multiattribute decisions provide outcom... more The common methods for studying heuristics in memorybased multiattribute decisions provide outcome and response time data but leave the foregoing cognitive processes in the dark. We demonstrate a novel process-tracing method that uses the looking-at-nothing phenomenon to study memory search and cue processing via eye tracking. Participants learned cue information of decision alternatives in spatial frames and later were presented with emptied displays of two alternatives in binary choice trials. With freely chosen and with instructed decision strategies, fixation patterns on former cue locations were in line with memory search and cue processing as postulated for lexicographic and compensatory strategies.
In sequential diagnostic reasoning the goal is to determine the most likely cause for a number of... more In sequential diagnostic reasoning the goal is to determine the most likely cause for a number of sequentially observed effects. Potential hypotheses are narrowed down by integrating the cumulating observed evidence leading to the selection of one among several hypotheses. In the reported diagnostic reasoning experiment, thirty-eight participants were tested with quasi-medical problems consisting of four sequentially presented symptoms with four candidate diagnostic hypotheses. We used ambiguous sequences that could be equally caused by two chemicals to investigate possible order effects and explicitly highlighted alternative hypotheses by using a stepwise rating procedure that also enabled us to compare participants' ratings with belief updating in a Bayes net. Even though alternatives were explicitly highlighted, participants were biased towards the initial hypothesis in a pair of equally supported hypotheses. We conclude that ambiguous symptom sets and nondiagnostic symptoms invite biased symptom processing and can produce primacy effects even in a step-by-step procedure.
The purpose in diagnostic reasoning is to find the cause of observed effects by applying knowledg... more The purpose in diagnostic reasoning is to find the cause of observed effects by applying knowledge about the effects and their potential causes. In the causal structure linking causes and effects, effects can share causes or be linked more indirectly. The causal diversity effect reflects the increased support of a cause by a more widespread distribution of effects within the underlying causal structure. We report two experiments, in which participants acquired knowledge about causal structures and then evaluated diverse and proximal effect patterns with regard to their support for inferring a cause. The diversity effect in diagnostic reasoning was stronger if participants had acquired integrated knowledge about causal structures. Moreover, teaching a reduced structure with less nodes open to alternative causation of proximal effects decreased the diversity effect. This confirmed that the causal diversity effect results from considering alternative causation and more generally that diagnostic reasoning draws on causal representations.
In sequential diagnostic reasoning, observed pieces of evidence activate hypotheses in memory and... more In sequential diagnostic reasoning, observed pieces of evidence activate hypotheses in memory and are integrated to reach a final diagnosis. The order of evidence can influence diagnostic reasoning. This article examines the processing of ambiguous evidence underlying order effects if multiple hypotheses are activated. In five experiments with a quasi-medical scenario, participants dealt with symptom sequences supporting multiple diagnoses. The symptom order, the response mode (end-of-sequence, step-by-step), and the consistency of evidence were manipulated. A primacy order effect occurred with both response modes suggesting that ambiguous pieces of evidence were distorted toward the hypothesis that strongly corresponded with the first piece. The primacy effect was partially counteracted by stepwise belief ratings, which strengthened the weight of recent evidence and promoted switching to an alternative diagnosis. We conclude that once hypotheses are generated, the interplay of coherence-oriented information distortion and memory-dependent analytic processes propagates into distinct order effects in diagnoses.
ABSTRACT In sequential diagnostic reasoning, observed evidence activates hypotheses about possibl... more ABSTRACT In sequential diagnostic reasoning, observed evidence activates hypotheses about possible causes in memory. These memory activations have been previously examined with a probe reaction task for problems with a single correct diagnosis. We applied this process tracing method to ambiguous problems with multiple compatible hypotheses. When participants reasoned about the causes of ambiguous symptom sequences, they were prompted to respond to probes representing hypotheses. The response time to a probe was shorter if the current support for the respective hypothesis was stronger indicating that the processing of compatible hypotheses can be traced. For sequences with two equally supported hypotheses, the initial hypothesis was more often chosen as the final diagnosis (a primacy effect). Probe reaction times suggest that the initial hypothesis has been activated more strongly already early, when it was finally chosen as the diagnosis. Nevertheless, substantial variance in response times limits the task's applicability for process tracing.
Transportation Research Part F: Traffic Psychology and Behaviour, 2005
Recent studies have explored a promising method to measure driver workload-the Peripheral Detecti... more Recent studies have explored a promising method to measure driver workload-the Peripheral Detection Task (PDT). The PDT has been suggested as a standard method to assess safety-relevant workload from the use of in-vehicle information systems (IVIS) while driving. This paper reports the German part of a Swedish-German cooperative study in which the PDT was investigated focusing on its specific sensitivity compared with alternative workload measures. Forty-nine professional drivers performed the PDT while following route guidance system instructions on an inner-city route. The route consisted of both highly demanding and less demanding sections. Two route guidance systems that differed mainly in display size and display organization were compared. Subjective workload ratings (NASA-TLX) as well as physiological measures (heart rate and heart rate variability) were collected as reference data. The PDT showed sensitivity to route demands. Despite their differing displays, both route guidance systems affected PDT performance similarly in intervals of several minutes. However, the PDT proved sensitive to peaks in workload from IVIS use and from the driving task. Peaks in workload were studied by video analyses of four selected subsections on the route. Subjective workload ratings reflected overall route demands and also did not indicate differing effects of the two displays. The physiological measures were less sensitive to workload and indicated emotional strain as well. An assessment of the PDT as a method for the measurement of safety-related workload is given.
The common methods for studying heuristics in memorybased multiattribute decisions provide outcom... more The common methods for studying heuristics in memorybased multiattribute decisions provide outcome and response time data but leave the foregoing cognitive processes in the dark. We demonstrate a novel process-tracing method that uses the looking-at-nothing phenomenon to study memory search and cue processing via eye tracking. Participants learned cue information of decision alternatives in spatial frames and later were presented with emptied displays of two alternatives in binary choice trials. With freely chosen and with instructed decision strategies, fixation patterns on former cue locations were in line with memory search and cue processing as postulated for lexicographic and compensatory strategies.
In sequential diagnostic reasoning the goal is to determine the most likely cause for a number of... more In sequential diagnostic reasoning the goal is to determine the most likely cause for a number of sequentially observed effects. Potential hypotheses are narrowed down by integrating the cumulating observed evidence leading to the selection of one among several hypotheses. In the reported diagnostic reasoning experiment, thirty-eight participants were tested with quasi-medical problems consisting of four sequentially presented symptoms with four candidate diagnostic hypotheses. We used ambiguous sequences that could be equally caused by two chemicals to investigate possible order effects and explicitly highlighted alternative hypotheses by using a stepwise rating procedure that also enabled us to compare participants' ratings with belief updating in a Bayes net. Even though alternatives were explicitly highlighted, participants were biased towards the initial hypothesis in a pair of equally supported hypotheses. We conclude that ambiguous symptom sets and nondiagnostic symptoms invite biased symptom processing and can produce primacy effects even in a step-by-step procedure.
The purpose in diagnostic reasoning is to find the cause of observed effects by applying knowledg... more The purpose in diagnostic reasoning is to find the cause of observed effects by applying knowledge about the effects and their potential causes. In the causal structure linking causes and effects, effects can share causes or be linked more indirectly. The causal diversity effect reflects the increased support of a cause by a more widespread distribution of effects within the underlying causal structure. We report two experiments, in which participants acquired knowledge about causal structures and then evaluated diverse and proximal effect patterns with regard to their support for inferring a cause. The diversity effect in diagnostic reasoning was stronger if participants had acquired integrated knowledge about causal structures. Moreover, teaching a reduced structure with less nodes open to alternative causation of proximal effects decreased the diversity effect. This confirmed that the causal diversity effect results from considering alternative causation and more generally that diagnostic reasoning draws on causal representations.
Uploads
Papers by Georg Jahn