Shinji Kitagami

Consolidation power of extrinsic rewards: reward cues enhance long-term memory for irrelevant past events.

Recent research suggests that extrinsic rewards promote memory consolidation through dopaminergic modulation processes. However, no conclusive behavioral evidence exists given that the influence of extrinsic reward on attention and motivation during encoding and consolidation processes are inherently confounded. The present study provides behavioral evidence that extrinsic rewards (i.e., monetary incentives) enhance human memory consolidation independently of attention and motivation. Participants saw neutral pictures, followed by a reward or control cue in an unrelated context. Our results (and a direct replication study) demonstrated that the reward cue predicted a retrograde enhancement of memory for the preceding neutral pictures. This retrograde effect was observed only after a delay, not immediately upon testing. An additional experiment showed that emotional arousal or unconscious resource mobilization cannot explain the retrograde enhancement effect. These results provide support for the notion that the dopaminergic memory consolidation effect can result from extrinsic reward.

Neuroscientific information bias in metacomprehension: The effect of brain images on metacomprehension judgment of neuroscience research

In the present study, we investigated how brain images affect metacomprehension judgments of neuroscience research. Participants made a prereading judgment of comprehension of the text topic and then read a text about neuroimaging findings. In Experiment 1, participants read text only or text accompanying brain images. In Experiment 2, participants read text accompanying bar graphs or text accompanying brain images. Then participants were asked to rate their comprehension of the text. Finally, they completed comprehension tests. The results of Experiment 1 showed that the text accompanying brain images was associated with higher metacomprehension judgments than was the text only, whereas the performance of the comprehension test did not differ between each condition. The results of Experiment 2 showed that the text accompanying brain images was associated not only with credibility of the text, but also with higher metacomprehension judgments than was the text accompanying the bar graphs, whereas the performance of the comprehension test did not differ between each condition. The findings suggest that the readers’ subjective judgments differ from actual comprehension.

An Extension of a Parallel-Distributed Processing Framework of Reading Aloud in Japanese: Human Nonword Reading Accuracy Does Not Require a Sequential Mechanism

Humans can pronounce a nonword (e.g., rint). Some researchers have interpreted this behavior as requiring a sequential mechanism by which a grapheme-phoneme correspondence rule is applied to each grapheme in turn. However, several parallel-distributed processing (PDP) models in English have simulated human nonword reading accuracy without a sequential mechanism. Interestingly, the Japanese psycholinguistic literature went partly in the same direction, but it has since concluded that a sequential parsing mechanism is required to reproduce human nonword reading accuracy. In this study, by manipulating the list composition (i.e., pure word/nonword list vs. mixed list), we demonstrated that past psycholinguistic studies in Japanese have overestimated human nonword reading accuracy. When the more fairly reevaluated human performance was targeted, a newly implemented Japanese PDP model simulated the target accuracy as well as the error patterns. These findings suggest that PDP models are a more parsimonious way of explaining reading across various languages.

The interactive effect of working memory and text difficulty on metacomprehension accuracy

We investigated how working memory capacity (WMC) and text difficulty affect metacomprehension accuracy. Participants completed the operation-span test to measure WMC and ability to read expository texts. Under the easy-text condition, participants read 4 texts with increasing local cohesion, whereas under the difficult-text condition, participants read 4 original texts. Participants assigned a comprehension rating to each text and then completed a comprehension test. The results revealed a significant interactive effect of WMC and text difficulty on metacomprehension accuracy in Experiments 1 and 2. Under the easy-text condition, higher-WMC readers monitored their comprehension less accurately than did lower-WMC readers. In contrast, higher-WMC readers monitored their comprehension more accurately than did lower-WMC readers under the difficult-text condition. These results suggest that text difficulty may affect allocation of attentional resources.

INFORMATION PROCESSING OF PICTOGRAMS AND THE VISUAL FIELD DIFFERENCE

The main purpose was to investigate how we process pictograms and to examine the effects of learning on visual field differences when participants overlearn the meaning of each pictogram. 15 students were required to judge whether the referent of each symbol was either larger or smaller than the referent of the standard stimulus (Test 1). Several days later the same task was conducted (Test 2). Although a right visual field advantage was observed in Test 1, it was not apparent at Test 2 after participants had studied the pictogram list repeatedly. These results suggest that pictograms might be processed in much the same way as other ordinary verbal stimuli at a very early stage of learning. Participants could, however, comprehend the pictograms by employing a kind of imagery processing after they were familiar with the symbols.

Why Verbalization of Non-Verbal Memory Reduces Recognition Accuracy: A Computational Approach to Verbal Overshadowing

Verbal overshadowing refers to a phenomenon whereby verbalization of non-verbal stimuli (e.g., facial features) during the maintenance phase (after the target information is no longer available from the sensory inputs) impairs subsequent non-verbal recognition accuracy. Two primary mechanisms have been proposed for verbal overshadowing, namely the recoding interference hypothesis, and the transfer-inappropriate processing shift. The former assumes that verbalization renders non-verbal representations less accurate. In contrast, the latter assumes that verbalization shifts processing operations to a verbal mode and increases the chance of failing to return to non-verbal, face-specific processing operations (i.e., intact, yet inaccessible non-verbal representations). To date, certain psychological phenomena have been advocated as inconsistent with the recoding-interference hypothesis. These include a decline in non-verbal memory performance following verbalization of non-target faces, and occasional failures to detect a significant correlation between the accuracy of verbal descriptions and the non-verbal memory performance. Contrary to these arguments against the recoding interference hypothesis, however, the present computational model instantiated core processing principles of the recoding interference hypothesis to simulate face recognition, and nonetheless successfully reproduced these behavioral phenomena, as well as the standard verbal overshadowing. These results demonstrate the plausibility of the recoding interference hypothesis to account for verbal overshadowing, and suggest there is no need to implement separable mechanisms (e.g., operation-specific representations, different processing principles, etc.). In addition, detailed inspections of the internal processing of the model clarified how verbalization rendered internal representations less accurate and how such representations led to reduced recognition accuracy, thereby offering a computationally grounded explanation. Finally, the model also provided an explanation as to why some studies have failed to report verbal overshadowing. Thus, the present study suggests it is not constructive to discuss whether verbal overshadowing exists or not in an all-or-none manner, and instead suggests a better experimental paradigm to further explore this phenomenon.

Verbalizing Information Salient to Face Identification Does Not Cause Verbal Overshadowing1

Abstract Attempting to describe a face can lead to subsequent recognition impairments, i.e., verbal overshadowing. A new explanation of the verbal overshadowing effect was tested by manipulating whether participants described features that were more or less salient for face identification. To manipulate the distinguishing features, distractor faces were created with gray scale photographs of men identical to the targets except for the eyes and mouth (Study 1) or eyebrows and nose (Study 2). In both studies, participants (Study 1: N = 177, 81 men, M age = 18.9 yr.; Study 2: N = 144, 133 men, M age = 20.5 yr.) were assigned to one of two verbalization conditions or a control condition. After a target face was presented, participants in the two verbalization conditions were asked to describe specific features—either eyes and mouth, or eyebrows and nose—before a recognition test. Participants in the control condition completed a filler task. The measure of recognition was whether participants could recognize ...