Aline Sevenants

Truth table tasks: The relevance of irrelevant

Two types of truth table tasks are used investigating mental representations of conditionals: a possibilities-based and a truth-based one. In possibilities tasks, participants indicate whether a situation is possible or impossible according to the conditional rule. In truth tasks participants evaluate whether a situation makes the rule true or false, or is irrelevant with respect to the truth of the rule. Comparing the two-option version of the possibilities task with the truth task in Experiment 1, the possibilities task yields logical answer patterns whereas the truth task yields defective patterns. Adding the irrelevant option to the possibilities task in Experiment 2 leads to a considerable amount of defective patterns in the possibilities task, but still to more logical patterns in the possibilities task than in the truth task. Experiment 3 shows that directionality matters since rule-to-situation tasks yield more logical answer patterns than do situation-to-rule tasks. We conclude that both task types are not comparable as such since wording, number of options and directionality influence the results.

Is the truth table task mistaken

There is ample evidence that in classical truth table task experiments false antecedents are judged as “irrelevant”. Instead of interpreting this in support of a suppositional representation of conditionals, Schroyens (2010a, 2010b) attributes it to the induction problem: the impossibility of establishing the truth of a universal claim on the basis of a single case. In the first experiment a truth table task with four options is administered and the correlation with intelligence is inspected. It is observed that “undetermined” is chosen in one third of the judgements and “irrelevant” in another third. A positive correlation is revealed between intelligence and the number of “irrelevant” and “undetermined” judgements. The data do not exclude that a part of the “irrelevant” judgements in classical truth table task experiments might be caused by the induction problem. In the second experiment participants are presented with a simplified four-option truth table task and asked for a justification of their judgements. These justifications show the induction problem is not the reason for choosing the “irrelevant” or “undetermined” option, which is supportive for a suppositional representation of conditionals.

Vroeger nadenken over later

SamenvattingRekening houden in de zorg met de wensen van mensen met dementie. Het lijkt een open deur, wie zou dat niet willen? Toch blijkt dit ideaal in de praktijk vaak nog ver te zoeken. Vroegtijdige zorgplanning is een manier om een cultuur van permanente dialoog op gang te brengen waardoor meer recht wordt gedaan aan wat mensen met dementie belangrijk vinden. Ook wanneer zij dit niet meer zelf onder woorden kunnen brengen.