Visual attribute modulates the time course of iconic memory decay

Studies on iconic memory demonstrate that rich information from a visual scene quickly becomes unavailable with the passage of time. The decay rate of iconic memory refers to the dynamics of memory availability. The present study investigated the iconic memory decay of different stimulus attributes that comprised an object. Specifically, in Experiment 1, participants were presented with eight coloured numbers (e.g., red 4) and required to remember only one attribute, either colour or number, over different blocks of trials. The participants then reported the cued attribute in which the cue Stimulus Onset Asynchrony (SOA) from the memory array onset was varied (0, 100, 200, 300, 500, and 1000?ms). We found that numerical information became unavailable more quickly than colour information, despite the fact that the memory accuracies at 0 and 1000?ms SOAs were comparable between the two attributes. In Experiment 2, we replicated the finding that a numerical representation was lost more quickly than a colour representation when visual masks followed the target stimulus. These results suggest that the various visual attributes comprising an object are lost over time at different rates in iconic memory. We discuss this finding in relation to how perceptual representation is transferred to the capacity-limited visual working memory.     

Imagery of errors in typing

Using a typing task we investigated whether insufficient imagination of errors and error corrections is related to duration differences between execution and imagination. In Experiment 1 spontaneous error imagination was investigated, whereas in Experiment 2 participants were specifically instructed to imagine errors. Further, in Experiment 2 we manipulated correction instructions (whether or not to correct errors) and controlled for visual feedback in executed typing (letters appearing on the screen or not). Participants executed and imagined typing proverbs of different lengths. Errors and error corrections explained a significant amount of variance of execution minus imagination differences in Experiment 1, and in Experiment 2 when participants were instructed to correct errors, but not when participants were instructed not to correct errors. In Experiment 2 participants corrected and reported more errors with than without visual feedback. However, the relation between execution − imagination duration differences and errors and error corrections was unaffected by visual feedback. The types of errors reported less often in imagination than in execution were related to processes in typing execution. We conclude that errors and error corrections are not spontaneously imagined during motor imagery, and that even when attention is drawn to their occurrence only some are imagined. This may be due to forward models not predicting all aspects of an action, imprecise forward models, or a neglect of monitoring error signals during motor imagery.     

Incidental visual memory for targets and distractors in visual search

We explored incidental retention of visual details of encountered objects during search. Participants searched for conjunction targets in 32 arrays of 12 pictures of real-world objects and then performed a token discrimination task that examined their memory for visual details of the targets and distractors from the search task. The results indicate that even though participants had not been instructed to memorize the objects, the visual details of search targets and distractor objects related to the targets were retained after the search. Distractor objects unrelated to the search target were remembered more poorly. Eye-movement measures indicated that the objects that were remembered were looked at more frequently during search than those that were not remembered. These results provide support that detailed visual information is included incidentally in the visual representation of an object after the object is no longer in view.     

Reducing the vividness and emotional impact of distressing autobiographical memories: the importance of modality-specific interference

Experimental analogues of post-traumatic stress disorder suggest that loading the visuospatial sketchpad of working memory with a concurrent task reduces the vividness and associated distress of predominantly visual images. The present experiments explicitly tested the hypothesis that interfering with the phonological loop could analogously reduce the vividness and emotional impact of auditory images. In Experiment 1, 30 undergraduates formed non-specific images of emotive autobiographical memories while performing a concurrent task designed to load either the visuospatial sketchpad (eye movements) or phonological loop (articulatory suppression). Participants reported their images to be primarily visual, corresponding to the greater dual-task disruption observed for eye movements. Experiment 2 instructed participants to form specifically visual or auditory images. As predicted, concurrent articulation reduced vividness and emotional intensity ratings of auditory images to a greater extent than did eye movements, whereas concurrent eye movements reduced ratings of visual images much more than did articulatory suppression. Such modality-specific dual-task interference could usefully contribute to the treatment and management of intrusive distressing images in both clinical and non-clinical settings.     

Visual mental imagery influences attentional guidance in a visual-search task

Visual mental imagery resembles visual working memory (VWM). Because both visual mental imagery and VWM involve the representation and manipulation of visual information, it was hypothesized that they would exert similar effects on visual attention. Several previous studies have demonstrated that working-memory representations guide attention toward a memory-matching task-irrelevant stimulus during visual-search tasks. Therefore, mental imagery may also guide attention toward imagery-matching stimuli. In the present study, five experiments were conducted to investigate the effects of visual mental imagery on visual attention during a visual-search task. Participants were instructed to visualize a color or an object clearly associated with a specific color, after which they were asked to detect a colored target in the visual-search task. Reaction times for target detection were shorter when the color of the target matched the imagined color, and when the color of the target was similar to that strongly associated with the imagined object, than when the color of the target did not match that of the mental representation. This effect was not observed when participants were not instructed to imagine a color. These results suggest that similar to VWM, visual mental imagery guides attention toward imagery-matching stimuli.     

言语记忆对视觉选择的影响:基于维度的自动注意引导

两个实验分别考察外显和内隐言语记忆中的特征维度信息对基于维度的视觉选择性注意的自动引导作用。实验一要求被试在言语工作记忆(外显言语记忆)保持阶段完成一个视觉注意任务,结果发现了显著的一致性效应,即记忆任务相关维度和注意任务相关维度不一致条件下的注意任务反应时要显著慢于两者一致条件下的反应时;实验二采用go/no-go任务以考察内隐言语记忆对视觉选择的影响,结果也发现了类似的一致性效应。这些结果表明外显和内隐言语记忆中的抽象维度信息自动引导注意选择视场中与之匹配的视觉维度,而不管该维度是否为当前注意任务的相关维度。     

Cultural differences in visual attention: Implications for distraction processing

We investigated differences between participants of East Asian and Western descent in attention to and implicit memory for irrelevant words which participants were instructed to ignore while completing a target task (a Stroop Task in Experiment 1 and a 1‐back task on pictures in Experiment 2 ). Implicit memory was measured using two conceptual priming tasks (category generation in Experiment 1 and general knowledge in Experiment 2 ). Participants of East Asian descent showed reliable implicit memory for previous distractors relative to those of Western descent with no evidence of differences on target task performance. We also found differences in a Corsi Block spatial memory task in both studies, with superior performance by the East Asian group. Our findings suggest that cultural differences in attention extend to task‐irrelevant background information, and demonstrate for the first time that such information can boost performance when it becomes relevant on a subsequent task.     

Visuospatial processing in memory for word location in writing

Two experiments examined how visuospatial processing engaged during text composition intervenes in memory for word location. Experiment 1 showed that in contrast to participants who performed a spatial task concurrently with composing a text, participants who performed a concurrent visual task recalled fewer word locations after the composition. Consequently, it is hypothesized that writers process the written text in order to visually represent its physical layout, and that this representation is then used when locating words. Experiment 2 tested this hypothesis by comparing a standard composition condition (with the written trace) with a condition in which the written trace was suppressed during composition, and with a condition without written trace and with added visual noise. Memory for word location only decreased with visual noise, indicating that construction of the visual representation of the text does not rely on the written trace but involves visual working memory.     

Double standards: Memory loading in temporal reference memory

Three experiments compared human performance on temporal generalization tasks with either one or two different, and distinct, standard durations encoded. In the first two experiments participants received presentations of two different standards at the beginning of each trial block and were instructed to encode either one or both of them. When instructed to encode one standard they then had to judge whether each of a number of comparison stimuli was or was not that standard. When instructed to encode both they were then tested using just one of the standards but the participants were unaware, at the time of encoding, which standard would later be used as a reference. No marked effect of the number of temporal standards encoded was found. In Experiment 3 participants received either one or two temporal standards and had to use both when two were presented. This manipulation produced flatter generalization gradients when two standards were encoded than when just one was, and modelling attributed this difference mainly to an increase in reference memory variability in the double-standard case. This suggests that the variability of representation of durations in temporal reference memory can be systematically increased by increasing temporal reference memory load.     

Dream rebound of suppressed emotional thoughts: the influence of cognitive load

Initial evidence suggests that suppressing a thought prior to sleep results in subsequent dreaming of that thought. The present research examined the influence of cognitive load on dreaming following suppression. In Experiment 1, 100 participants received either a suppression instruction or no instruction for an intrusive thought prior to sleep, and subsequently completed a dream diary. Participants instructed to suppress reported dreaming about the target thought more than controls; dream rebound was predicted by poorer performance on a working memory task. In Experiment 2, 126 participants received either a suppression instruction or no instruction for an intrusive thought prior to sleep, and half of participants also had cognitive load of learning a 9-digit number. Participants receiving the suppression instruction under cognitive load reported greater dream rebound than other participants. These findings indicate that thought suppression prior to sleep leads to dream rebound, and this effect is enhanced by cognitive load.     

说明文阅读中因果序列的表征

结合自定步调阅读与句子启动再认范式, 探讨说明文阅读过程中因果序列的表征问题。研究包括3个实验, 实验1的文本提供一个包括4个概念的因果链(如, A－B－C－D), 文本最后设置包含概念A或概念B或概念C的句子, 对概念D进行探测, 结果发现, 对于概念D的再认启动作用, 概念C＞概念B＞概念A; 实验2改变因果链的说明顺序, 使之与因果链本身次序不一致, 结果与实验1一致; 实验3的文本分别介绍两条独立的因果链(如A－B－C; D－E－F), 最后呈现包含概念A或概念D的句子, 对概念C进行探测, 结果发现, 包含概念A的句子理解启动了相关因果链, 使读者对随后呈现的概念C的再认反应加快。基于本研究结果, 结合相关研究, 本文尝试提出说明文文本表征的建构模式。     

编码方式对陌生字形记忆的影响

采用学习-再认范式,分别以韩字、英文假词为实验材料,考察了编码方式对陌生字形记忆的影响。在学习阶段,通过随机呈现整体和部分探测刺激,引导被试分别以整体编码和部分编码方式学习陌生字形,并在学习结束后一小时进行再认记忆测试。结果发现,无论以韩字还是以英文假词为材料,部分编码条件的记忆成绩均显著好于整体编码。该结果说明部分编码相比于整体编码能促进陌生字形记忆,并且这种优势效应具有跨文字系统的一致性。     

Computation of mean size is based on perceived size

The present study investigated whether computation of mean object size was based on perceived or physical size. The Ebbinghaus illusion was used to make the perceived size of a circle different from its physical size. Four Ebbinghaus configurations were presented either simultaneously (Experiment 1) or sequentially (Experiment 2) to each visual field, and participants were instructed to attend only to the central circles of each configuration. Participants’ judgments of mean central circle size were influenced by the Ebbinghaus illusion. In addition, the Ebbinghaus illusion influenced the coding of individual size rather than the averaging. These results suggest that perceived rather than physical size was used in computing the mean size.     

The representation of nonstructural information in visual memory: Evidence from image combination

Two experiments investigated the differential representation of the figure and ground of a picture in visual short-term and long-term memory. It is known (Hitch, Brandimonte, & Walker, 1995) that subjects find it more difficult to combine mental images of two separately presented pictures in order to identify a novel form when the two pictures are incongruent in color (i.e., when a black-on-white line drawing has to be combined with a white-on-black drawing). In the present experiments, thefigures were depicted in solid form to allow color congruity to be varied independently for figure and ground. Results showed a clear impairment in image combination when the to-be-combined figures were incongruent in color (black-on-gray and white-on-gray) but not when theirgrounds were incongruently colored (gray-on-black and gray-on-white). In this way, image combination was seen to be supported by a representation of the object depicted in the picture rather than by a literal representation of the picture itself (i.e., a pictorial code). In line with previous findings, the same representation was seen to support image combination based on short-term memory (Experiment 1) and long-term memory (Experiment 2), provided that in the latter case verbal recoding was precluded. When verbal recoding was allowed, image combination based on long-term memory was insensitive to color congruity, implying the involvement of a more abstract structural representation.     

Playing on the typewriter, typing on the piano: manipulation knowledge of objects

Two experiments investigated sensory/motor-based functional knowledge of man-made objects: manipulation features associated with the actual usage of objects. In Experiment 1, a series of prime-target pairs was presented auditorily, and participants were asked to make a lexical decision on the target word. Participants made a significantly faster decision about the target word (e.g. ‘typewriter’) following a related prime that shared manipulation features with the target (e.g. ‘piano’) than an unrelated prime (e.g. ‘blanket’). In Experiment 2, participants' eye movements were monitored when they viewed a visual display on a computer screen while listening to a concurrent auditory input. Participants were instructed to simply identify the auditory input and touch the corresponding object on the computer display. Participants fixated an object picture (e.g. “typewriter”) related to a target word (e.g. ‘piano’) significantly more often than an unrelated object picture (e.g. “bucket”) as well as a visually matched control (e.g. “couch”). Results of the two experiments suggest that manipulation knowledge of words is retrieved without conscious effort and that manipulation knowledge constitutes a part of the lexical-semantic representation of objects.     

Assessment of calibration for reconstructed eye-witness memories

Two experiments examined confidence judgments associated with eyewitness memory for events to misinformation [Loftus, E. F. (1975). Leading questions and the eyewitness report. Cognitive Psychology, 7, 560-572]. Participants in each experiment watched videos depicting crimes and either responded to questionnaires (Experiment 1) or read narratives (Experiment 2) containing veridical or non-veridical information. Upon testing for memory performance 24 h later, participants exposed to misinformation accepted the misinformation as part of their memory of the events in the videos. In both experiments, confidence judgments of participants subjected to misinformation were high and comparable to those of participants not subjected to misinformation. The relationship between accurate responding and confidence was assessed via calibration analysis [Yates, J. F. (1990). Judgments and decision making. Englewood Cliffs, NJ: Prentice Hall]. Performance on various measures of calibration was generally better for participants who were not exposed to misinformation. We conclude that confidence judgments can depend on factors other than those that improve the accuracy of memory, such as the retrieval fluency of one’s memories.     

Influence of head orientation on visually and memory-guided arm movements

In the absence of visual supervision, tilting the head sideways gives rise to deviations in spatially defined arm movements. The purpose of this study was to determine whether these deviations are restricted to situations with impoverished visual information. Two experiments were conducted in which participants were positioned supine and reproduced with their unseen index finger a 2 dimensional figure either under visual supervision or from memory (eyes closed). In the former condition, the figure remained visible (using a mirror). In the latter condition, the figure was first observed and then reproduced from memory. Participants' head was either aligned with the trunk or tilted 30° towards the left or right shoulder. In experiment 1, participants observed first the figure with the head straight and then reproduced it with the head either aligned or tilted sideways. In Experiment 2, participants observed the figure with the head in the position in which the figure was later reproduced. Results of Experiment 1 and 2 showed deviations of the motor reproduction in the direction opposite to the head in both the memory and visually-guided conditions. However, the deviations decreased significantly under visual supervision when the head was tilted left. In Experiment 1, the perceptual visual bias induced by head tilt was evaluated. Participants were required to align the figure parallel to their median trunk axis. Results revealed that the figure was perceived as parallel with the trunk when it was actually tilted in the direction of the head. Perceptual and motor responses did not correlate. Therefore, as long as visual feedback of the arm is prevented, an internal bias, likely originating from head/trunk representation, alters hand-motor production irrespectively of whether visual feedback of the figure is available or not.