Source memory that encoding was self-referential: the influence of stimulus characteristics

Decades of research suggest that encoding information with respect to the self improves memory (self-reference effect, SRE) for items (item SRE). The current study focused on how processing information in reference to the self affects source memory for whether an item was self-referentially processed (a source SRE). Participants self-referentially or non-self-referentially encoded words (Experiment 1) or pictures (Experiment 2) that varied in valence (positive, negative, neutral). Relative to non-self-referential processing, self-referential processing enhanced item recognition for all stimulus types (an item SRE), but it only enhanced source memory for positive words (a source SRE). In fact, source memory for negative and neutral pictures was worse for items processed self-referentially than non-self-referentially. Together, the results suggest that item SRE and source SRE (e.g., remembering an item was encoded self-referentially) are not necessarily the same across stimulus types (e.g., words, pictures; positive, negative). While an item SRE may depend on the overall likelihood the item generates any association, the enhancing effects of self-referential processing on source memory for self-referential encoding may depend on how embedded a stimulus becomes in one’s self-schema, and that depends, in part, on the stimulus’ valence and format. Self-relevance ratings during encoding provide converging evidence for this interpretation.     

Emotive concept nouns and motor responses: Attraction or repulsion?

We carried out three experiments aimed at testing whether hand posture affects the compatibility effect that Chen and Bargh (1999) found between a word’s emotional connotation and arm movement direction. In the present study, participants responded by pressing two buttons: one placed near their body, the other far away. In Experiment 1, in which they pressed the response button with their hand open, RTs were shorter when participants pressed the far button for positive words and the near button for negative words, as if they simulated reaching for something good and avoiding something bad. However, in Experiments 2 and 3, in which participants pressed the response button with a tennis ball in their hand, RTs were shorter when participants pressed the near button for positive words and the far button for negative words, as if they simulated drawing a good thing closer and pushing a bad thing away. Results are discussed within the framework of theories on concept grounding in emotion and action systems.     

Repetition and laterality effects on recognition memory for words and pictures*

Recognition memory for a list of words was tested by presenting a series of items with Ss instructed to make positive responses to targets (list items) and negative responses to distractors (nonlist items). The test items were either words or pictures, and they were presented tachistoscopically either to the left or right visual field. The results showed mean response latencies to be generally faster for stimuli presented to the right visual field. Response times were faster for target and distractor stimuli on their second test presentations than on initial tests, but this effect was much larger for targets. Repetitions were shown to decrease the amount of time necessary to execute the stimulus encoding and initial retrieval stages of recognition. This was also true, although to a lesser extent, if different stimulus forms (words or pictures) were used on the two tests. Subsequent recognition stages, including memory search and decision processes. were apparently independent of test stimulus form.     

Episodic encoding and recognition of pictures and words: role of the human medial temporal lobes

In the present PET study, we examined brain activity related to processing of pictures and printed words in episodic memory. Our goal was to determine how the perceptual format of objects (verbal versus pictorial) is reflected in the neural organization of episodic memory for common objects. We investigated this issue in relation to encoding and recognition with a particular focus on medial temporal-lobe (MTL) structures. At encoding, participants saw pictures of objects or their written names and were asked to make semantic judgments. At recognition, participants made yes-no recognition judgments in four different conditions. In two conditions, target items were pictures of objects; these objects had originally been encoded either in picture or in word format. In two other conditions, target items were words; they also denoted objects originally encoded either as pictures or as words. Our data show that right MTL structures are differentially involved in picture processing during encoding and recognition. A posterior MTL region showed higher activation in response to the presentation of pictures than of words across all conditions. During encoding, this region may be involved in setting up a representation of the perceptual information that comprises the picture. At recognition, it may play a role in guiding retrieval processes based on the perceptual input, i.e. the retrieval cue. Another more anterior right MTL region was found to be differentially involved in recognition of objects that had been encoded as pictures, irrespective of whether the retrieval cue provided was pictorial or verbal in nature; this region may be involved in accessing stored pictorial representations. Our results suggest that left MTL structures contribute to picture processing only during encoding. Some regions in the left MTL showed an involvement in semantic encoding that was picture specific; others showed a task-specific involvement across pictures and words. Together, our results provide evidence that the involvement of some but not all MTL regions in episodic encoding and recognition is format specific.     

Presentation format effects in working memory: The role of attention

Four experiments are reported in which participants attempted to remember three or six concrete nouns, presented as pictures, spoken words, or printed words, while also verifying the accuracy of sentences. Hypotheses meant to explain the higher recall of pictures and spoken words over printed words were tested. Increasing the difficulty and changing the type of processing task from arithmetic to a visual/spatial reasoning task did not influence recall. An examination of long-term modality effects showed that those effects were not sufficient to explain the superior performance with spoken words and pictures. Only when we manipulated the allocation of attention to the items in the storage task by requiring the participants to articulate the items and by presenting the stimulus items under a degraded condition were we able to reduce or remove the effect of presentation format. The findings suggest that the better recall of pictures and spoken words over printed words result from the fact that under normal presentation conditions, printed words receive less processing attention than pictures and spoken words do.     

Emotion-induced modulation of recognition memory decisions in a Go/NoGo task: Response bias or memory bias?

In recognition memory tests for words, items with negative emotional meaning are more often classified as “old” compared to neutral items, whether or not they are in fact old. Two accounts for this bias have been offered: One proposes that emotions disrupt retrieval and response monitoring processes (executive control account), the other proposes that emotions cause illusory feelings of remembering (memory bias account). We addressed this issue by varying the target signal in a Go/NoGo variant of a recognition memory task for negative, neutral, and positive words and faces: One group of participants was asked to respond to old items whereas the other group was asked to respond to new items. Results showed that the “Go-for-old” group showed the typical emotion-induced response bias shift for both positive and negative words, while the “Go-for-new” group showed the opposite pattern. Results were nonsignificant for faces, but went into the same direction. The findings are clearly inconsistent with the executive control account and speak for a genuine memory illusion induced by emotional arousal.     

刺激类型及表征关系对无意视盲的影响

通过考察刺激类型以及重叠呈现的图片流和词语流的表征关系对非注意刺激的捕获差异,试图考察刺激类型和表征关系对无意视盲（Inattentional Blindness）的影响。分别有20名中学生参加了词和图片基线水平测试,52名中学生参与了无意视盲实验。研究结果表明：（1）当词与图片重叠呈现时,不管注意刺激是词还是图片,也不管词与图片的表征是否一致,与基线水平相比,被试都出现了显著的无意视盲现象。（2）当词与图片的表征意义一致时,如果注意刺激是图片,而非注意刺激是词,那么被试更容易觉察到非注意刺激。（3）非注意刺激与注意刺激表征意义一致时更容易捕获观察者的注意     

Divided attention enhances the recognition of emotional stimuli: evidence from the attentional boost effect

The present study examined predictions of the early-phase-elevated-attention hypothesis of the attentional boost effect (ABE), which suggests that transient increases in attention at encoding, as instantiated in the ABE paradigm, should enhance the recognition of neutral and positive items (whose encoding is mostly based on controlled processes), while having small or null effects on the recognition of negative items (whose encoding is primarily based on automatic processes). Participants were presented a sequence of negative, neutral and positive stimuli (pictures in Experiment 1, words in Experiment 2) associated to target (red) squares, distractor (green) squares or no squares (baseline condition). They were told to attend to the pictures/words and simultaneously press the spacebar of the computer when a red square appeared. In a later recognition task, stimuli associated to target squares were recognised better than stimuli associated to distractor squares, replicating the standard ABE. More importantly, we also found that: (a) the memory enhancement following target detection occurred with all types of stimuli (neutral, negative and positive) and (b) the advantage of negative stimuli over neutral stimuli was intact in the DA condition. These findings suggest that the encoding of negative stimuli depends on both controlled (attention-dependent) and automatic (attention-independent) processes.     

The relationship between the amygdala and bed nucleus of the stria terminalis in the cat: an evoked potential and single cell study

The effects of amygdala stimulation on excitability of cells in the bed nucleus of the stria terminalis (BNST) were investigated in the cat. The predominant effect of stimulation was to excite cells localized in the lateral BNST. Cells responded either with single spikes to a stimulus pulse or in short bursts. Spontaneous firing of cells after a pulse to the amygdala was observed to both increase and decrease over a 4-s interval. Increases in firing rate, however, were the predominant response. Cells in more anterior locations in the BNST responded with latencies shorter than those of cells in more posterior locations, reflecting either differences in conduction time of excitation from the amygdala or differences in transmitters mediating the excitatory effects. Associated with increases in cell firing was a compound field potential with an initial negative component and a later positive component. These components may be generated by different cell types within the BNST. The negative component likely represents a field EPSP. Effective sites of amygdala stimulation were restricted to the posterior basal amygdala, and effects observed in the BNST were restricted to the lateral BNST. These data correspond well with anatomical studies showing a monosynaptic projection of basal amygdala to lateral BNST in the cat. This study suggests that this projection is predominantly excitatory.     

Visual effects in picture and word categorization

Two experiments are reported in which participants categorized stimuli as belonging or not belonging to the category of fruits. Blocks of pictures and words were used, with items referring to exemplars having either high or low intercategory visual similarity and/or semantic relatedness. For both pictures and words, response time was longer in the semantically related conditions than in the unrelated condition. Furthermore, there was a strong effect of visual similarity for pictures but not for words when semantic relatedness was held constant: Participants took longer to classify pictures of fruits when these were mixed with visually similar vegetables than when they were mixed with visually dissimilar vegetables. Reducing the stimulus visibility by adding a dot pattern had an additive effect for words but an interactive effect for pictures. The results are explained in terms of a unique locus for category decisions about pictures and words.     

汉词和图画再认的ERP效应及脑机制

目的：比较汉词与图画材料再认过程中的事件相关电位（ERP）表现并探讨其脑机制。方法：使用经典“学习一再认”实验模式对21名大学生进行测验,同时记录EEG,离线处理后对汉词及图画再认诱发的ERP波形主要成分及新旧效应进行比较。结果：两种材料的再认均诱发出了明显的新旧效应。顶区新旧效应头皮分布基本一致,但图画再认该效应波幅大于汉词再认;两种材料诱发的额区新旧效应有所不同,图画再认该效应为正走向,而汉词再认此效应表现为负走向趋势。结论：汉词与图画再认既存在某种共同的神经加工机制,叉分别涉及一些特异性的神经活动模式。     

中等强度情绪性图片的神经机制——一项fMRI研究

采用修订后的中等唤起度的国际情绪图片为刺激材料,以12名女性大学生为被试,考察情绪性图片引起的脑激活模式。结果发现,与中性条件相比,消极情绪图片激活了枕叶、杏仁核、海马旁回和壳核。积极情绪图片引起枕叶、内侧眶额、额中回等脑区的激活,研究结果再次验证了杏仁核与消极情绪的密切关系,同时推测,内侧眶额可能是中等唤起度的趋近性积极情绪的一个脑功能区。     

Pictorial encoding effects and memory confusions in the Deese–Roediger–McDermott paradigm: Evidence for the activation of spontaneous imagery

The purpose of the experiments reported in this paper was to examine the possible role of spontaneous imagery and list-specific cues on pictorial encoding effects induced by the Deese-Roediger-McDermott (DRM) task. After viewing pictures and words referring to thematically related materials, by way of a picture/word source-judgement task, participants were asked to remember the way in which these materials were presented. Participants reported “seeing” pictures of items that were presented as words, an effect predicted by the imaginal activation hypothesis in its suggestion that incidental images experienced during encoding will later be mistaken as memories for pictures. Whether participants made the same picture misattributions on related lures (or non-presented related items) depended on the way in which the lures’ respective thematic lists were experienced during encoding (Experiments 1 and 2), pointing to the effects of list-specific cues in picture/word judgements. These findings have intriguing implications for interpretations of picture-encoding effects induced by the DRM task. The findings also speak to the use of DRM false-memory rates when marshalling evidence against the use of imagery in applied settings.     

Hemispheric alpha asymmetries of words with positive, negative, and neutral arousal values preceding tasks of recall and recognition: Electrophysiological and behavioral results from stuttering males and nonstuttering males and females

Hemispheric alpha asymmetries were obtained for stuttering males and nonstuttering males and females for words of positive, negative, and neutral arousal values. Electroencephalographic data were gathered during the presentations of stimulus words and during the actual nonoral recall and recognition of the stimulus items. Stuttering males demonstrated right-hemispheric alpha suppression across stimulus words and tasks as contrasted with left-hemispheric alpha suppression for the nonstuttering males and females. Stuttering males were also shown to recall and recognize fewer words than the nonstuttering subjects across arousal categories. Subjects were also administered a modified version of A. Paivio's (1971, In B. Randhawa & W. Coffman, Eds., Visual thinking, learning, and communication, New York: Academic Press) Individual Differences Questionnaire (IDQ). Results showed our stuttering males to have obtained lower scores on the verbal and imagery questions of the IDQ as compared to the nonstuttering groups. Hemispheric alpha asymmetry results and memory performance from the stuttering males are discussed relative to nonsegmental, right-hemispheric processing strategies.     

Developmental differences in frequency judgments of words and pictures

Children in kindergarten, third, and fifth grades were presented a list of either pictures or words (with items presented for varying numbers of times on the study trial). In both picture and word conditions, half of the Ss estimated how many times each item had been presented (absolute judgments) and the other half judged which of two items had occurred more often on the study trial (relative judgments). The primary finding was that while frequency judgment performance improved with age for both pictures and words, there was relatively greater improvement for pictures (i.e., the picture-word difference increased with age). These results lend strong support to the frequency theory of discrimination learning and, in particular, may be useful in accounting for effects associated with age and with age by stimulus mode interactions.     

The positivity proportion effect: A list context effect in masked affective priming

In the evaluative decision task, participants decide whether target words denote something positive or negative. Positive and negative prime words are known to engender so-called affective priming effects in this task. Primes were sandwich masked, and the proportion of positive to negative target words was manipulated. In Experiment 1, prime valence and positivity proportion interacted, so that primes of the less frequently presented target valence caused larger priming effects. Experiment 2 rendered an explanation of this interaction in terms of response bias unlikely, Experiment 3 ruled out a peripheral locus of the effect, and Experiment 4 ruled out an account in terms of stimulus repetition. The effect is explained by means of an attentional bias favoring the rare kind of valence.     

Conditions of directed attention inhibit recognition performance for explicitly presented target-aligned irrelevant stimuli

The fate of irrelevant and overtly presented stimuli that was temporally aligned with an attended target in a separate task was explored. Seitz and Watanabe (2003) demonstrated that if an irrelevant motion stimulus was implicit (i.e., subthreshold), a later facilitation for the same motion direction was observed if the previously presented implicit motion (of the same direction) was temporally aligned with the presence of an attended target. Later research, however, demonstrated that if the motion stimulus aligned with the attended target was explicit (i.e., suprathreshold), a later inhibition was observed (Tsushima, Seitz, & Watanabe, 2008). The current study expands on this by using more salient stimuli (words and pictures) in an inattentional blindness paradigm, and suggests that when attention is depleted, recognition for target-aligned task-irrelevant items is impaired in a subsequent recognition task. Participants were required to respond to either immediate picture, or word, repetitions in a stream of simultaneously presented line drawings and written words, and later given a surprise recognition test that measured recognition for the words or the pictures. When analyzing word recognition performance after attention had been directed to the pictures, words that had appeared simultaneously with a picture repetition in the repetition detection task were recognized at levels significantly below chance. The same inhibition was mirrored when testing for picture recognition after having attended to the words in the repetition detection task. These data suggest an inhibitory mechanism that is exhibited in later recognition tests for salient information that was previously unattended and had been simultaneously being presented with an attended target in a different task.     

Mapping the apetitive and aversive systems with emotional pictures using a block-design fMRI procedure

Negative emotional pictures from the International Affective Pictures System (IAPS) have been successful in mapping brain areas related to the aversive system. However, the capacity of positive emotional pictures to study the brain areas related to the appetitive system (i.e., nucleus accumbens, prefrontal cortex) is less established. In this study, we used a block fMRI design to investigate this issue, including emotional pictures as background while participants performed a vowel-consonant discrimination task. Importantly, participants were heterosexual males and all positive pictures were related to erotic couples, opposite-sex erotica, or romantic scenes. Negative pictures were similar to those used in previous studies. Results were consistent with previous studies using event-related designs, showing activation of amygdala, lateral prefrontal cortex, and occipito-temporal areas, but positive pictures showed a significant activation in the left nucleus accumbens. These findings provide evidence of the utility of block designs in emotional research (positive emotional pictures).     

An increase in stimulus arousal has differential effects on the processing speed of pleasant and unpleasant stimuli

The arousal value of a stimulus influences its salience, whereby higher arousal should lead to faster processing. However, in previous research, participants consistently made faster valence judgments for low arousal, pleasant stimuli than for high arousal, pleasant stimuli. The speed of valence and arousal judgments for pictures and words were investigated in three experiments. Valence judgments were faster for low arousal than for high arousal pleasant pictures and for high arousal than for low arousal unpleasant pictures and words. Moreover, arousal judgments were faster for low arousal than high arousal pleasant and for high arousal than low arousal unpleasant pictures and words. The current research confirms that the impact of valence and arousal on processing speed does not reflect on the labels (valence versus arousal) used when recording speeded judgments. Similarly to valence, stimulus arousal interacts differentially with the evaluation of pleasant and unpleasant stimuli producing a processing advantage for high arousal, unpleasant stimuli but not high arousal, pleasant stimuli.