Disruption Of Short-term Memory Research Articles

False memories through auditory distraction: When irrelevant speech produces memory intrusions in the absence of semantic interference.

Task-irrelevant speech is known to cause disruption of short-term memory, either through specific interference with encoding processes (e.g., seriation, semantic processing) or by diverting attention from the focal task. Previous studies found that semantically related background speech can induce memory intrusions of words that were not part of the to-be-remembered list. While these findings suggest false memories due to semantic interference, the present study aims to test whether the presence of task-irrelevant speech affects the susceptibility to memory intrusions also in the absence of semantic interference. Therefore, incomprehensible to-be-ignored speech was presented during encoding of semantically related words. It was found across three experiments that incomprehensible changing-state speech increased the rate of false memories of non-presented but semantically related words in a subsequent recognition (Experiments 1 and 2) or recall test (Experiment 3), compared with white noise or steady-state speech. The findings indicate that speech interfered with serial-order processing of the to-be-remembered items, thus urging participants to rely on semantic information to encode and retrieve the presented words. While a focus on semantic information enabled participants to correctly recollect the majority of presented words, it most likely also increased the proportion of false memories of words with semantic associations to the presented words both in recall and recognition tests. In all three experiments, the presence of an auditory deviant in background speech did not increase the rate of false memories, suggesting that attentional capture alone does not necessarily induce source monitoring errors. However, Experiment 3 revealed that an increase in visual task-encoding load attenuated the changing-state effect on the production of false memories. This indicates that the semantic organisation processes initiated as a result of the loss of order information in case of changing-state speech may be sensitive to attentional control.

Emotional prosody of task-irrelevant speech interferes with the retention of serial order.

Task-irrelevant speech and other temporally changing sounds are known to interfere with the short-term memorization of ordered verbal materials, as compared to silence or stationary sounds. It has been argued that this disruption of short-term memory (STM) may be due to (a) interference of automatically encoded acoustical fluctuations with the process of serial rehearsal or (b) attentional capture by salient task-irrelevant information. To disentangle the contributions of these 2 processes, the authors investigated whether the disruption of serial recall is due to the semantic or acoustical properties of task-irrelevant speech (Experiment 1). They found that performance was affected by the prosody (emotional intonation), but not by the semantics (word meaning), of irrelevant speech, suggesting that the disruption of serial recall is due to interference of precategorically encoded changing-state sound (with higher fluctuation strength of emotionally intonated speech). The authors further demonstrated a functional distinction between this form of distraction and attentional capture by contrasting the effect of (a) speech prosody and (b) sudden prosody deviations on both serial and nonserial STM tasks (Experiment 2). Although serial recall was again sensitive to the emotional prosody of irrelevant speech, performance on a nonserial missing-item task was unaffected by the presence of neutral or emotionally intonated speech sounds. In contrast, sudden prosody changes tended to impair performance on both tasks, suggesting an independent effect of attentional capture. (PsycINFO Database Record

Specific foreknowledge reduces auditory distraction by irrelevant speech.

In a series of experiments, it was tested whether distraction by changing-state irrelevant speech is inevitable or can be modulated by foreknowledge of an imminent to-be-ignored distractor sequence. Participants were required to remember visually presented digits while ignoring background speech. In the foreknowledge condition of Experiment 1, the upcoming to-be-ignored sentence was presented auditorily and visually before each trial. With specific foreknowledge, the changing-state irrelevant sound effect (here, increased disruption by sentences compared with repeated words) was significantly attenuated relative to a condition without foreknowledge. This finding was replicated in Experiment 2, in which the information about the upcoming auditory distractor speech was presented only in the visual modality. Experiment 3 showed that only specific foreknowledge of the auditory distractor material has beneficial effects on the ability to ignore distraction. The mere notification that an unspecified distractor sentence would be presented next had no effect on distraction. In Experiment 4, there was only a small and not statistically significant reduction of the irrelevant speech effect when lists of randomly selected words were used as distractor material, suggesting that foreknowledge effects are more pronounced for highly variable, meaningful distractor material. We conclude that the disruption of short-term memory by irrelevant speech is not purely a stimulus-driven process that is immune to top-down control. A significant proportion of the effect can be modulated by specific knowledge about an imminent distractor sequence.

Age equivalence in auditory distraction by changing and deviant speech sounds.

The present study was designed to examine age-related differences in the disruption of short-term memory by changing and deviant speech sounds. In total, 128 old and 130 young adults performed a serial recall task while ignoring (a) steady-state sequences in which the same distractor word was repeated 12 times, (b) auditory deviant sequences in which the ninth distractor word deviated from the otherwise repetitive context, and (c) changing state sequences in which 12 different distractor words were presented. According to inhibitory deficit theory, older adults should generally be more susceptible to auditory distraction. The duplex-mechanism account of auditory distraction is based on the idea that the changing state effect and the auditory deviant effect are functionally different. It suggests that older adults should be more impaired by auditory deviants than younger adults but equally able to ignore changing state sequences. The age-invariant distractibility account predicts no age differences in auditory distraction, which was confirmed by the present results. Old adults performed worse than young adults in the serial recall task. In both age groups, however, the changing state effect (i.e., increased disruption by changing state sequences relative to steady-state sequences) and the auditory deviant effect (i.e., increased disruption by auditory deviant sequences relative to steady-state sequences) were equivalent. These effects were also unrelated to individual differences in working memory capacity.

Disruption of short-term memory by distractor speech: Does content matter?

Four experiments replicate the finding that auditory distractors that are lexically identical to the visual target items dramatically increase the irrelevant-speech effect on serial recall. This effect was previously attributed to interference of incompatible order cues. The present results suggest that a different interpretation of this effect is required. Experiment 2 replicates the order congruence effect observed by Hughes and Jones (2005), but shows that this effect is most likely due to an attenuation of interference that is caused by strategic attention shifts to the nominally irrelevant material. Experiments 3 and 4 show that the between-stream similarity effect generalizes to a condition in which the distractor items were drawn from the same category as the targets, but were not identical to them. By showing that nonacoustic distractor features can increase interference in serial recall of lists of supposedly "meaningless" items such as digits or consonants, the results are most consistent with models that postulate an integration of short-term and long-term memory such as the embedded-processes model and the feature model and are inconsistent with classical structural accounts of memory.

Changes in the Activity of Amyloid-Degrading Metallopeptidases Leads to Disruption of Memory in Rats

In old male Wistar rats (older than 12 months), or adult males (3-4 months) subjected to prenatal hypoxia (7% 02, 3 h, E14), a disruption of short-term memory was observed. The prenatal hypoxia also led to a decrease in the brain cortex expression of metallopeptidases neprilysin (NEP) and endothelin-converting enzyme (ECE-1) which regulate some neuropeptides and are the main beta-amyloid-degrading enzymes. Moreover, a significant decrease (by 2.7 times) in NEP activity in the sensorimotor cortex of old and adult rats subjected to prenatal hypoxia (by 1.7 times) was observed. To confirm possible involvement of these enzymes in memory, the analysis of the effect of microinjections of phosphoramidon (an inhibitor of NEP and ECE-1), and thiorphan (an inhibitor of NEP) into the rat sensorimotor cortex was carried out. In a two-level radial maze test, a disruption of short-term memory was observed 60 and 120 min after i.c. injection ofphosphoramidon (5.9 microg/microl) and 30 and 60 min after i.c. injection of thiorphan (2.5 microg/microl). The involvement of NEP and ECE-1 in short-term memory suggests that a decrease in the level of expression and activity of metallopeptidases involved in metabolism of beta-amyloid peptide (Abeta) and other neuropeptides is one of the main factors in disruption of cognitive functions after prenatal hypoxia or in the process of ageing.

Disruption of short-term memory by changing and deviant sounds: Support for a duplex-mechanism account of auditory distraction.

The disruption of short-term memory by to-be-ignored auditory sequences (the changing-state effect) has often been characterized as attentional capture by deviant events (deviation effect). However, the present study demonstrates that changing-state and deviation effects are functionally distinct forms of auditory distraction: The disruption of visual-verbal serial recall by changing-state speech was independent of the effect of a single deviant voice embedded within the speech (Experiment 1); a voice-deviation effect, but not a changing-state effect, was found on a missing-item task (Experiment 2); and a deviant voice repetition within the context of an alternating-voice irrelevant speech sequence disrupted serial recall (Experiment 3). The authors conclude that the changing-state effect is the result of a conflict between 2 seriation processes being applied concurrently to relevant and irrelevant material, whereas the deviation effect reflects a more general attention-capture process.

Cognitive correlates of long-term cannabis use in Costa Rican men.

Cognitive correlates of long-term cannabis use have been elusive. We tested the hypothesis that long-term cannabis use is associated with deficits in short term memory, working memory, and attention in a literate, westernized culture (Costa Rica) in which the effects of cannabis use can be isolated. Two cohorts of long-term cannabis users and nonusers were studied. Within each cohort, users and nonusers were comparable in age and socioeconomic status. Polydrug users and users who tested positive for the use of cannabis at the time of cognitive assessment after a 72-hour abstention period were excluded. The older cohort (whose age was approximately 45 years) had consumed cannabis for an average of 34 years, and comprised 17 users and 30 nonusers, who had been recruited in San José, Costa Rica, and had been observed since 1973. The younger cohort (whose age was approximately 28 years) had consumed cannabis for an average of 8 years, and comprised 37 users and 49 nonusers. Short-term memory, working memory, and attentional skills were measured in each subject. Older long-term users performed worse than older nonusers on 2 short-term memory tests involving learning lists of words. In addition, older long-term users performed worse than older nonusers on selective and divided attention tasks associated with working memory. No notable differences were apparent between younger users and nonusers. Long-term cannabis use was associated with disruption of short-term memory, working memory, and attentional skills in older long-term cannabis users.

Privileged access by irrelevant speech to short-term memory: the role of changing state.

Memory for visually presented items is impaired by speech that is played as an irrelevant background. The paper presents the view that changing state of the auditory material is an important prerequisite for this disruption. Four experiments studied the effects of sounds varying in complexity in an attempt to establish which features of changing state in the auditory signal lead to diminished recall. Simple unvarying or repetitive speech sounds were not sufficient to induce the irrelevant speech effect (Experiment 1): in addition, simple analogues of speech, possessing regular or irregular envelopes and using a range of carriers, failed to imitate the action of speech (Experiment 2). Variability of between-utterance phonology in the irrelevant stream (Experiment 3) emerged as a crucial factor. Moreover, predictability of the syllable sequence did not reduce the degree of disruption (Experiment 4) suggesting that supra-syllabic characteristics of the speech are of little importance. The results broadly support the idea that disruption of short-term memory only occurs when the speech stream changes in state. It is argued that disruption occurs in memory when cues to serial order based on phonological representations of heard material interfere with the phonological codes of visual origin. It is suggested that cues to changing state of the speech input contaminate those associated with items of visual origin, which are already in a phonological store.

Disruption of short-term memory by unattended speech: Implications for the structure of working memory

A series of experiments studied the effect of unattended speech on immediate memory for visually presented digits. Memory performance showed clear impairment, with the degree of impairment being a function of the phonological similarity of the irrelevant words to the visually presented digits. In contrast, the semantic characteristics of the unattended speech did not influence performance. Requiring the subject to suppress articulation removed the disrupting effect of irrelevant speech. These results are interpreted in terms of two separate memory systems of which one relies on a phonological code. The system is accessible in two ways, through auditory presentation leading to obligatory registration of the material, or through an optional subvocal rehearsal process.

Disruption of short-term memory in man following consumption of ethanol

Over a 45-min period, accuracy of recognition of previously presented pictures systematically decreased in 10 nonalcoholics after a moderate amount of alcohol was consumed. The decline in performance was relatively greater when the number of pictures between the old picture and its question was larger, suggesting that alcohol affected retrieval as well as attention mechanisms.

On the disruption of short-term memory by a response prefix.

On the disruption of short-term memory by a response prefix.