In formal interviews it is important that interviewees indicate when they do not know the answer, rather than speculate. In this study we investigated whether question format affected the tendency to speculate. One hundred and twenty-eight 5-to 9-year-olds, and 23 adults, were told two short stories, and were then asked questions about the stories. Half of the questions were answerable based on the information provided; the other half were not answerable. Within these categories, half of the questions were closed questions (i.e. only required a yes/no response), and half were wh-questions (i.e. requested particular details to be provided). All participants performed at ceiling with the answerable questions. With the unanswerable questions, there was an effect of format. The majority of children and adults correctly indicated that they did not know the answer when asked unanswerable wh-questions. However, the majority of children, and just over one-®fth of adults, provided a response (i.e.`yes' or`no') to the closed unanswerable questions. The implications for interviews, particularly within a forensic context, are discussed.

Previous researchers found that young children will try to answer nonsensical questions. In Expt 1, 5-to 8-year-olds were asked sensible and nonsensical questions. Half of each type were 'closed' questions (which required a yes/no response), and half were 'open' questions (which could be answered in several ways). Three weeks later the same children were asked to judge if the questions were sensible or silly. Children answered all the sensible questions appropriately, and only attempted to answer a small proportion of the nonsensical open questions. However, they did try to answer three-quarters of the nonsensical closed questions. Nonetheless, children were nearly always correct in judging which questions were sensible and which were nonsensical. In Expt 1 all the closed nonsensical questions were also ones that required a comparison between two items. In Expt 2 we compared children's responses to nonsensical open and closed questions when half of each type were comparative and half were non-comparative. Children attempted to answer nonsensical closed questions irrespective of whether or not they included a comparison. However, few children attempted to answer nonsensical open questions. We discuss the implications of these results for questioning children and in the context of children's eyewitness testimony.

In visual working memory tasks, memory for an item is enhanced if participants are told that the item is relatively more valuable than others presented within the same trial. Experiment 1 explored whether these probe value boosts (termed prioritization effects in previous literature) are affected by probe frequency (i.e., how often the more valuable item is tested). Participants were presented with four colored shapes sequentially and asked to recall the color of one probed item following a delay. They were informed that the first item was more valuable (differential probe value) or as valuable as the other items (equal probe value), and that this item would be tested more frequently (differential probe frequency) or as frequently (equal probe frequency) as the other items. Probe value and probe frequency boosts were observed at the first position, though both were accompanied by costs to other items. Probe value and probe frequency boosts were additive, suggesting the manipulations yield independent effects. Further supporting this, experiment 2 revealed that probe frequency boosts are not reliant on executive resources, directly contrasting with previous findings regarding probe value. Taken together, these outcomes suggest there may be several ways in which attention can be directed in working memory.

Children are interviewed in a variety of contexts, for example, in the legal setting and in experimental research. In these situations, it is often very important that children indicate when they do not know the answer to a question, rather than guess. In the present experiment, one hundred and forty-nine 5-to 9-year-olds witnessed a staged event in one of two conditions. The interviewer was either present at the event (knowledgeable interviewer) or absent from the event (uninformed interviewer). Children were then interviewed using yes/no questions and wh-questions. Within each type of question, half were answerable based on the information provided; the other half were not answerable (i.e. the correct answer was 'don't know'). The children performed consistently well with the answerable questions. With the unanswerable questions, there was an effect of format and interviewer knowledge. Children were more likely correctly to indicate that they did not know the answer to an unanswerable wh-question than an unanswerable yes/no question. Also, children were more likely correctly to say 'don't know' to unanswerable questions when the interviewer had been absent from the event.

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