Working memory demands of exact and approximate addition

We compared the working memory requirements of two forms of mental addition: exact calculation (e.g., 63 + 49 = 112) and approximation (e.g., 63 + 49 is about 110). In two experiments, participants solved two-digit addition problems (e.g., 63 + 49) alone and in combination with a working memory task (i.e., remembering four consonants). In Experiment 1, participants chose an answer from two alternatives (e.g., exact: 112 vs. 122; approximate: 110 vs. 140). In Experiment 2, participants responded verbally with exact or approximate answers. In both experiments, the working memory load impaired exact and approximate addition performance, but exact addition was affected more. Load also impaired performance on problems with a carry operation in the units (e.g., 28 + 59 or 76 + 57) more than on problems without a unit carry (e.g., 24 + 53 or 76 + 52). These results identify the carry operation as the source of the working memory demands in multidigit addition.     

Does source memory impairment associated with emotionally arousing stimuli occur at encoding or retrieval?

The present experiment investigated whether negatively arousing stimuli produce source memory impairment and whether the impairment occurs at encoding or retrieval. Participants were presented with negatively arousing, positively arousing, and neutral pictures. Each picture was followed by an instructional slide that indicated whether the picture was an Apple-kind or an Orange-kind. Item memory was assessed by free recall and source memory was assessed by asking participants to classify the recalled pictures into the two kinds of pictures. The results indicated that item memory was greater for the negatively arousing pictures than for the positively arousing and the neutral pictures. However, the negatively arousing pictures produced more misattribution errors than the neutral pictures, replicating source memory impairment. It was concluded that source memory impairment associated with negatively arousing stimuli occurs at encoding.     

Correcting erroneous inferences in memory: The role of source credibility

People often continue to rely on erroneous information about people and events, even in the face of subsequent counter information. The current study examined whether this information could be effectively corrected by a credible source. We examined two aspects of credibility: trustworthiness and expertise. Experiment 1 showed that receiving a correction from a source high in trustworthiness and expertise reduced participants’ use of original information when making inferences. Experiment 2 showed that source expertise alone was not sufficient to reduce participants’ reliance on the original information. The results from Experiment 3 showed that source trustworthiness alone significantly decreased participants’ use of the original information when making inferences. The results suggest that people may be able to reduce their use of original information if they receive a correction from a person who is deemed to be highly trustworthy. These findings have implications for decision making in politics and other applied areas.     

编码任务对来源记忆的影响:一项事件相关电位研究

本研究采用ERPs技术,探讨编码任务对来源记忆的影响及其神经机制。在学习阶段,被试进行两种编码操作：匹配判断任务和大小判断任务;在测验阶段,让被试进行来源判断任务。行为结果发现：在编码阶段,匹配判断任务比大小判断任务需要更长的时间;在测验阶段,匹配判断任务在“项目旧/背景旧”和“部分旧”条件的正确率显著高于大小判断任务,匹配判断任务在“项目旧/背景旧”条件的反应时显著短于大小判断任务。测验阶段ERPs结果发现：两种编码任务的新旧效应在200~700ms均有较广泛的头皮分布,而在700~1100ms呈前额皮层最大化分布;匹配判断任务的新旧效应比大小判断任务更大,表现在600~700ms的FPz电极以及700~800ms的Pz、P4电极。由此可见,在来源记忆中,编码任务影响来源记忆,主要表现在后部顶区位置;晚期前额皮层新旧效应不受任务难度因素的影响。     

Children's working understanding of knowledge sources: Confidence in knowledge gained from testimony

In three experiments, children aged between 3 and 5 years (N = 38, 52, 94; mean ages 3–7 to 5–2) indicated their confidence in their knowledge of the identity of a hidden toy. With the exception of some 3-year-olds, children revealed working understanding of their knowledge source by showing high confidence when they had seen or felt the toy, and lower confidence when they had been told its identity by an apparently well-informed speaker. Correct explicit source reports were not necessary for children to show relative uncertainty when the speaker subsequently doubted the adequacy of his access to the toy. After a 2-min delay, 3–4-year-olds, unlike 4–5-year-olds, failed to see the implications of the speaker's doubt about his access.     

When credibility attacks: The reverse impact of source credibility on persuasion

Recent research on the self-validation hypothesis suggests that source credibility identified after message processing can influence the confidence people have in their own thoughts generated in response to persuasive messages (Briñol, Petty, & Tormala, 2004). The present research explored the implications of this effect for the possibility that high credibility sources can be associated with more or less persuasion than low credibility sources. In two experiments, it is demonstrated that when people generate primarily positive thoughts in response to a message (e.g., because the message contains strong arguments) and then learn of the source, high source credibility leads to more favorable attitudes than does low source credibility. When people have primarily negative thoughts in response to a message (e.g., because it contains weak arguments), however, this effect is reversed—that is, high source credibility leads to less favorable attitudes than does low source credibility.     

Reduced misinformation effects following saccadic bilateral eye movements

The effects of saccadic bilateral (horizontal) eye movements on memory for a visual event narrative were investigated. In the study phase, participants were exposed to a set of pictures accompanied by a verbal commentary describing the events depicted in the pictures. Next, the participants were asked either misleading or control questions about the depicted event and were then asked to engage in 30s of bilateral vs. vertical vs. no eye movements. Finally, recognition memory was tested using the remember-know procedure. It was found that bilateral eye movements increased true memory for the event, increased recollection, and decreased the magnitude of the misinformation effect. The findings are discussed in terms of source monitoring, dual-process theories of memory and the potential neural foundations of such effects.     

Reading is believing: the truth effect and source credibility

Five experiments explored how source reliability influences people’s tendency to rate statements as more credible when they were encountered earlier (the truth effect). Undergraduates read statements from one reliable source and one unreliable source. Statements read multiple times were perceived as more valid and were more often correctly identified on a general knowledge test than statements read once or not at all. This occurred at varying retention intervals whether the statements originated from a reliable or unreliable source, when people had little memory for the statements themselves or their source, and when the discrediting information about the sources came either before or after reading the facts. While repetition aided recognition and source accuracy, both were unaffected by the reliability of the source. Consistent with the source monitoring framework, familiarity may create an illusion of truth for statements when people lack source-specifying cues, especially cues regarding the reliability of the source.     

Forgotten but not gone: Context effects on recognition do not require explicit memory for context

Context effects on recognition memory provide an important indirect assay of associative learning and source memory. Neuropsychological studies have indicated that such context effects may obtain even if the contexts themselves are not remembered—for example, in individuals impaired on direct tests of memory for contextual information. In contrast, a recent study indicated that the effects of temporal context reinstatement on visual recognition obtain only when the contextual information itself was explicitly recollected. Here we report that the effects of reinstatement of spatial-simultaneous context on visual object recognition memory obtain irrespective of whether those context stimuli are explicitly recognized. We suggest that spatial-simultaneous context effects might be based on ensemble unitization of target and context stimuli at encoding, whereas temporal context effects may require recollective processes.     

Inconsistency effects in source memory and compensatory schema-consistent guessing

The attention–elaboration hypothesis of memory for schematically unexpected information predicts better source memory for unexpected than expected sources. In three source-monitoring experiments, the authors tested the occurrence of an inconsistency effect in source memory. Participants were presented with items that were schematically either very expected or very unexpected for their source. Multinomial processing tree models were used to separate source memory, item memory, and guessing bias. Results show an inconsistency effect in source memory accompanied by a compensatory schema-consistent guessing bias when expectancy strength is high, that is, when items are very expected or very unexpected for their source.