Effects of Irrelevant Sounds on Phonological Coding in Reading Comprehension and Short term Memory

The effects of irrelevant sounds on reading comprehension and short-term memory were studied in two experiments. In Experiment 1, adults judged the acceptability of written sentences during irrelevent speech, accompanied and unaccompanied singing, instrumental music, and in silence. Sentences varied in syntactic complexity: Simple sentences contained a right-branching relative clause ( The applause pleased the woman that gave the speech ) and syntactically complex sentences included a centre-embedded relative clause ( The hay that the farmer stored fed the hungry animals ). Unacceptable sentences either sounded acceptable ( The dog chased the cat that eight up all his food ) or did not ( The man praised the child that sight up his spinach ). Decision accuracy was impaired by syntactic complexity but not by irrelevant sounds. Phonological coding was indicated by increased errors on unacceptable sentences that sounded correct. These error rates were unaffected by irrelevant sounds. Experiment 2 examined effects of irrelevant sounds on ordered recall of phonologically similar and dissimilar word lists. Phonological similarity impaired recall. Irrelevant speech reduced recall but did not interact with phonological similarity. The results of these experiments question assumptions about the relationship between speech input and phonological coding in reading and the short-term store.     

The irrelevant sound effect in short-term memory: Is there developmental change?

With two experiments, effects of irrelevant speech and classroom noise on serial recall of common nouns presented pictorially were investigated in children and adults. Experiment 1 used fixed list lengths for children (first graders) and adults. Experiment 2 used list lengths adjusted to participants' (second–third graders, adults) individual spans. In both experiments, children and adults were equally impaired by irrelevant speech. This contrasts with a related study (differences in methodology) by Elliott (2002), who reported severe increase in the detrimental impact of irrelevant speech with decreasing age. In both experiments, classroom noise had no effect in overall analyses. For Experiment 1, however, separate group analyses revealed impairment in children. Results suggest that effects of irrelevant sounds on serial recall stem from two separate mechanisms: Specific interference due to the sounds' automatic access to short-term memory, and/or attention capture. Only for the latter there is developmental change.     

Age differences in collaborative memory: the role of retrieval manipulations

In two experiments, we examined age differences in collaborative inhibition (reduced recall in pairs of people, relative to pooled individuals) across repeated retrieval attempts. Younger and older adults studied categorized word lists and were then given two consecutive recall tests and a recognition test. On the first recall test, the subjects were given free-report cued recall or forced-report cued recall instructions (Experiment 1) or free recall instructions (Experiment 2) and recalled the lists either alone or in collaboration with another subject of the same age group. Free-report cued recall and free recall instructions warned the subjects not to guess, whereas forcedreport cued recall instructions required them to guess. Collaborative inhibition was obtained for both younger and older adults on initial tests of free-report cued recall, forced-report cued recall, and free recall, showing that the effect generalizes across several tests for both younger and older adults. Collaborative inhibition did not persist on subsequent individual recall or recognition tests for list items. Older adults consistently falsely recalled and recognized items more than did younger adults, as had been found in previous studies. In addition, prior collaboration may exaggerate older adults’ tendency toward higher false alarms on a subsequent recognition test, but only after a free recall test. The results provide generality to the phenomenon of collaborative inhibition and can be explained by invoking concepts of strategy disruption and source monitoring.     

Does irrelevant music cause an irrelevant sound effect for auditory items?

The irrelevant sound effect (ISE) describes the significant reduction in verbal serial recall during irrelevant sounds with distinct temporal-spectral variations (changing-state sound). Whereas the ISE is well-documented for the serial recall of visual items accompanied by irrelevant speech and nonspeech sounds, an ISE caused by nonspeech sounds has not been reported for auditory items. Closing this empirical gap, Experiment 1 (n=90) verified that instrumental staccato-music reduces auditory serial recall compared to legato-music and silence. Its detrimental impact was not due to perceptual masking, disturbed encoding, or increased listening effort, as the employed experimental design and methods ensured. The found nonspeech ISE in auditory serial recall is corroborated by Experiment 1b (n=60), which, by using the same experimental design and methods, replicated the well-known ISE during irrelevant changing-state speech compared to steady-state speech, pink noise, and silence.     

Disruption of memory for lip-read lists by irrelevant speech: Further support for the changing state hypothesis

Two experiments critically re-examine the finding of Campbell and Dodd (1984, Experiment 2), which suggests that irrelevant speech disrupts the encoding of visual material for serial recall. Support is sought for the competing view that the effect of irrelevant speech is on storage by comparing the effect of a range of acoustic conditions on memory for graphic and lip-read lists. Initially, serial short-term recall of visually presented lists was examined with irrelevant speech that was both asynchronous with the visually presented items and of varied speech content (Experiment 1a). In this experiment substantial impairments in recall of both graphic and lip-read lists were found. However, with unvarying asynchronous speech (Experiment 1b) the effect of speech was small and non-significant. Experiment 2 examined the effect of changing state and of synchrony of speech with lip movements. When conditions of synchronous and asynchronous unvarying speech were contrasted, no significant effect of synchrony or irrelevant speech was found (Experiment 2a and 2c). In contrast, when the speech was varying in content, a strong effect of irrelevant speech was found; moreover, the effect was roughly the same for synchronous and asynchronous materials (Experiment 2b). The contrast in outcome with varying and unvarying speech provides strong support for the “changing state” model of the irrelevant speech effect. Coupled with the absence of an effect of synchrony in Experiment 2, these experiments reinforce the view that disruption by irrelevant speech occurs in memory, not at encoding.     

Memory illusions: false recall and recognition in adults with Asperger's syndrome

As persons on the autistic spectrum are known not to use semantic features of word lists to aid recall, they might show diminished susceptibility to illusory memories that typically occur with lists of associated items. Alternatively, since such individuals also have poor source monitoring, they might show greater susceptibility. The authors found that adults with Asperger's syndrome (n = 10) recalled similar proportions of a nonpresented strong associate of the study list items, compared with controls (n = 15). In Experiment 2, rates of true and false recognition of study list associates did not differ significantly between Asperger (n = 10) and control (n = 10) participants. Moreover, the Asperger participants made fewer remember and more know judgments than controls for veridical but not for false recognitions. Thus, deficits found in some aspects of memory in people with Asperger's syndrome do not affect their susceptibility to memory illusions.     

The irrelevant sound phenomenon revisited: what role for working memory capacity?

High-span individuals (as measured by the operation span [OSPAN] technique) are less likely than low-span individuals to notice their own names in an unattended auditory stream (A. R. A. Conway, N. Cowan, & M. F. Bunting, 2001). The possibility that OSPAN accounts for individual differences in auditory distraction on an immediate recall test was examined. There was no evidence that high-OSPAN participants were more resistant to the disruption caused by irrelevant speech in serial or in free recall. Low-OSPAN participants did, however, make more semantically related intrusion errors from the irrelevant sound stream in a free recall test (Experiment 4). Results suggest that OSPAN mediates semantic components of auditory distraction dissociable from other aspects of the irrelevant sound effect.     

The irrelevant-speech effect and children: theoretical implications of developmental change

The irrelevant-speech effect refers to the finding of impaired recall performance in the presence of irrelevant auditory stimuli. Two broad classes of theories exist for the effect, both allowing automatic entry of the distracting sounds into the processing system but differing in how attention is involved. As one source of evidence in the discussion of existing theories of the irrelevant-speech effect, the performance of children and adults on a visual serial recall task with irrelevant sounds (speech and tones) was examined. The magnitude of the effects of irrelevant sounds on performance decreased with age. The developmental differences were marked in the conditions with the greatest need for attentional control (words and especially changing words). The findings were interpreted with respect to current models of memory. Theories of the irrelevant-speech effect that include a role for attentional control were better suited to handle the results than those without a specified role for attention.     

Irrelevant Sound Disrupts Order Information in Free Recall as in Serial Recall

The claim that the sensitivity of free recall to disruption by irrelevant sound is a function of the extent to which rote rehearsal is employed as a mnemonic strategy was investigated in two experiments. The degree of disruption by irrelevant sound in terms of both item and order information was contrasted under serial and free recall instructions. Irrelevant sound was found to disrupt order and item information equally in serial and free recall tasks (Experiment 1). Contrary to previous reports, an effect of irrelevant sound was also demonstrated on free recall of particularly long lists, and the interaction between list length and retention interval in the irrelevant sound effect was examined (Experiment 2). Generally, the results support the view that irrelevant sound disrupts the use of order cues.     

Similarities between the irrelevant sound effect and the suffix effect

Although articulatory suppression abolishes the effect of irrelevant sound (ISE) on serial recall when sequences are presented visually, the effect persists with auditory presentation of list items. Two experiments were designed to test the claim that, when articulation is suppressed, the effect of irrelevant sound on the retention of auditory lists resembles a suffix effect. A suffix is a spoken word that immediately follows the final item in a list. Even though participants are told to ignore it, the suffix impairs serial recall of auditory lists. In Experiment 1, the irrelevant sound consisted of instrumental music. The music generated a significant ISE that was abolished by articulatory suppression. It therefore appears that, when articulation is suppressed, irrelevant sound must contain speech for it to have any effect on recall. This is consistent with what is known about the suffix effect. In Experiment 2, the effect of irrelevant sound under articulatory suppression was greater when the irrelevant sound was spoken by the same voice that presented the list items. This outcome is again consistent with the known characteristics of the suffix effect. It therefore appears that, when rehearsal is suppressed, irrelevant sound disrupts the acoustic-perceptual encoding of auditorily presented list items. There is no evidence that the persistence of the ISE under suppression is a result of interference to the representation of list items in a postcategorical phonological store.     

Children and adults are differentially affected by presentation modality in the DRM paradigm

Using the Deese–Roediger–McDermott (DRM) method for free recall, we examined mode of list presentation and association type in 8–9 year old children and adults. Participants verbally recalled lists of associates that were presented orally (Experiment 1) or visually (Experiment 2). Lists consisted of semantic associates (e.g. hound, puppy, etc.), phonological associates (e.g. log, dot, etc.) and both semantic and phonological associates (e.g. hound, dot, etc.) to a nonpresented lure word (e.g. dog). Interestingly, the ratio of false to true recall was higher in children than adults only when lists were presented orally. These results suggest that children rely more on sublexical information or item‐specific information than adults when reading lists, and, thus, are less likely to activate the critical lure via lexical associations. Furthermore, these results suggest that information processing differences at encoding between children and adults need to be taken into account when interpreting free recall studies. Copyright © 2008 John Wiley & Sons, Ltd.     

Recall of short word lists presented visually at fast rates: Effects of phonological similarity and word length

Phonological similarity of visually presented list items impairs short-term serial recall. Lists of long words are also recalled less accurately than are lists of short words. These results have been attributed to phonological recoding and rehearsal. If subjects articulate irrelevant words during list presentation, both phonological similarity and word length effects are abolished. Experiments 1 and 2 examined effects of phonological similarity and recall instructions on recall of lists shown at fast rates (from one item per 0.114-0.50 sec), which might not permit phonological encoding and rehearsal. In Experiment 3, recall instructions and word length were manipulated using fast presentation rates. Both phonological similarity and word length effects were observed, and they were not dependent on recall instructions. Experiments 4 and 5 investigated the effects of irrelevant concurrent articulation on lists shown at fast rates. Both phonological similarity and word length effects were removed by concurrent articulation, as they were with slow presentation rates.     

Auditory memory and the irrelevant sound effect: Further evidence for changing-state disruption

Four experiments investigate the hypothesis that irrelevant sound interferes with serial recall of auditory items in the same fashion as with visually presented items. In Experiment 1 an acoustically changing sequence of 30 irrelevant utterances was more disruptive than 30 repetitions of the same utterance (the changing-state effect; Jones, Madden, & Miles, 1992) whether the to-be-remembered items were visually or auditorily presented. Experiment 2 showed that two different utterances spoken once (a heterogeneous compound suffix; LeCompte & Watkins, 1995) produced less disruption to serial recall than 15 repetitions of the same sequence. Disruption thus depends on the number of sounds in the irrelevant sequence. In Experiments 3a and 3b the number of different sounds, the "token-set" size (Tremblay & Jones, 1998), in an irrelevant sequence also influenced the magnitude of disruption in both irrelevant sound and compound suffix conditions. The results support the view that the disruption of memory for auditory items, like memory for visually presented items, is dependent on the number of different irrelevant sounds presented and the size of the set from which these sounds are taken. Theoretical implications are discussed.     

Age-related differences in irrelevant-speech effects

Three experiments examined age-related differences in irrelevant-speech effects. Younger and older adults were required to recall short prose texts or lists of semantically related words presented visually together with distractor speech. In all experiments, older adults made more semantically related intrusion errors from the irrelevant speech than younger adults. Results of a source memory test suggested that these age-related differences in interference are most likely due to both inhibitory deficits and source-monitoring problems. The results lend partial support to the inhibition deficit theory of cognitive aging.     

The impact of broadband noise on serial memory: changes in band-pass frequency increase disruption

Irrelevant sound consisting of bursts of broadband noise, in which centre frequency changes with each burst, markedly impaired short-term memory for order. In contrast, a sequence of irrelevant sound in which the same band-pass noise burst was repeated did not produce significant disruption. Serial recall for both visual-verbal (Experiment 1) and visual-spatial items (Experiment 2) was sensitive to the increased disruption produced by changing irrelevant noise. The results provide evidence that sounds that are largely aperiodic can produce marked disruption of serial recall in a similar manner to periodic sounds (e.g., speech, musical streams, and tones), and thus show a changing-state effect.     

What happens to information to be suppressed in working-memory tasks? Short and long term effects

The study explored, from an individual differences point of view, what happens to information to be suppressed in a working-memory task at short and long term. In particular, it was examined whether control mechanisms of irrelevant information in working memory imply their complete elimination from working memory or just the modulation of their activation. To this end, we compared the fate of irrelevant information in groups of subjects with high and low reading comprehension (Experiments 1 and 2) and subjects with high and low working memory (Experiments 1, 2, 3, and 4). All the experiments presented a working-memory task devised by De Beni, Palladino, Pazzaglia, and Cornoldi (1998), which required participants to process lists of words, to tap when a word from a particular category was presented, and then to recall only the last items in each list. Results confirmed that participants with high reading comprehension also have higher working memory and make less intrusion errors due to irrelevant items that have to be processed but then discarded. Furthermore, it was found that participants with low working memory have slightly better implicit (Experiment 1) and explicit memory (Experiments 3 and 4) of highly activated irrelevant information. Nevertheless, in a long-term recognition test, participants with high and low reading comprehension/working memory presented a similar pattern of memory for different types of irrelevant information (Experiment 2), whereas in a short-term memory recognition test, low-span participants presented a facilitation effect in the time required for the recognition of highly activated irrelevant information (Experiment 4). It was concluded that efficient working-memory performance is related to the temporary reduction of activation of irrelevant information but does not imply its elimination from memory.     

The sources of visual recency: Movement and language in serial recall

Four experiments examine the importance of movement—the sequential ordering of stimulus features—in producing recency in the ordered serial recall of visual lists. The written recall of handsigns produced more recency when they were seen moving than still (Experiment I). Number lists presented as moving bar figures showed more recency than numbers which were displayed in the normal way with all features displayed simultaneously (Experiment II). The order in which features of abstract shapes are displayed can, itself, determine recency (Experiment III). However, a final experiment showed that still lip pictures of speech sounds generate more recency than letters representing those speech sounds. Therefore movement of stimulus features need not account for the extensive recency advantage in remembering lipread lists. The theoretical implications of these findings are discussed.     

Auditory memory and the irrelevant sound effect: Further evidence for changing-state disruption

Four experiments investigate the hypothesis that irrelevant sound interferes with serial recall of auditory items in the same fashion as with visually presented items. In Experiment 1 an acoustically changing sequence of 30 irrelevant utterances was more disruptive than 30 repetitions of the same utterance (the changing-state effect; Jones, Madden, & Miles, 1992) whether the to-be-remembered items were visually or auditorily presented. Experiment 2 showed that two different utterances spoken once (a heterogeneous compound suffix; LeCompte & Watkins, 1995) produced less disruption to serial recall than 15 repetitions of the same sequence. Disruption thus depends on the number of sounds in the irrelevant sequence. In Experiments 3a and 3b the number of different sounds, the "token-set" size (Tremblay & Jones, 1998), in an irrelevant sequence also influenced the magnitude of disruption in both irrelevant sound and compound suffix conditions. The results support the view that the disruption of memory for auditory items, like memory for visually presented items, is dependent on the number of different irrelevant sounds presented and the size of the set from which these sounds are taken. Theoretical implications are discussed.     

Disruption of visual short-term memory by changing-state auditory stimuli: The role of segmentation

Typically, serial recall performance can be disrupted by the presence of an irrelevant stream of background auditory stimulation, but only if the background stream changes over time (the auditory changing-state effect). It was hypothesized that segmentation of the auditory stream is necessary for changing state to be signified. In Experiment 1, continuous random pitch glides failed to disrupt serial recall, but glides interrupted regularly by silence brought about the usual auditory changing-state effect. In Experiment 2, a physically continuous stream of synthesized vowel sounds was found to have disruptive effects. In Experiment 3, the technique of auditory induction showed that preattentive organization rather than critical features of the sound could account for the disruption by glides. With pitch glides, silence plays a preeminent role in the temporal segmentation of the sound stream, but speech contains corr-elated-time-varying changes in frequency and amplitude that make silent intervals superfluous.     

A left-ear disadvantage for the presentation of irrelevant sound: manipulations of task requirements and changing state

Three experiments attempted to clarify the effect of altering the spatial presentation of irrelevant auditory information. Previous research using serial recall tasks demonstrated a left-ear disadvantage for the presentation of irrelevant sounds (). Experiments 1 and 2 examined the effects of manipulating the location of irrelevant sound on either a mental arithmetic task () or a missing-item task (; Experiment 4). Experiment 3 altered the amount of change in the irrelevant stream to assess how this affected the level of interference elicited. Two prerequisites appear necessary to produce the left-ear disadvantage; the presence of ordered structural changes in the irrelevant sound and the requirement for serial order processing of the attended information. The existence of a left-ear disadvantage highlights the role of the right hemisphere in the obligatory processing of auditory information.