Interference and auditory short-term memory in the bottlenosed dolphin

Interference in auditory short-term memory in the bottlenosed dolphin,Tursiops truncatus (Montagu), was studied using a delayed matching-to-sample task. At each trial, one of two sample sounds, chosen randomly, was projected underwater for 4 sec and then, after a variable delay interval, both sounds were presented. A response to the sound matching the initial sample was reinforced. Correct matching was significantly reduced following short intervals between trials in combination with long delays after the sample (proactive interference), or when a near continuous irrelevant sound was inserted into the delay interval (retroactive interference). There was rapid habituation to interference if the irrelevant sound was short in duration relative to the delay interval. For both proactive and retroactive interference, the errors were predominantly responses to the sample sound appropriate to the prior trial rather than to the current trial, indicating that memory for the relative recency of events (temporal memory) was degraded by interference. When interference was deleted or minimized, temporal memory remained nearly perfect over 30-sec delay intervals, the longest tested. The importance of distinguishing between temporal memory and nontemporal, or event, memory in different forms of the delayed matching task was emphasized.     

Symbolic,identity, and probe delayed matching of sounds by the bottlenosed dolphin

The short-term memory for sounds of the bottlenosed dolphin was tested using symbolic, identity, and probe forms of the delayed matching-to-sample (DMS) task. The forms differed in the number (one or two) or nature (symbolic or identity matches of sample sounds) of postdelay test stimuli available as memory retrieval cues. Although symbolic DMS was difficult to learn, the final performance level was approximately equal to that for identity or probe DMS. On all tasks, the dolphin’s responses were above 80% correct through to delays of 90 sec and, in some cases, through to delays of 180 and 240 sec, the “limits” being governed mainly by the dolphin’s reluctance to continue being tested at long delays. Encoding of sample stimuli into their learned symbolic representation was hypothesized to have reduced symbolic DMS to a recognition memory task, resulting in the observed equivalence of performance with the other two recognition memory tasks. The probe DMS results, unlike those for identity or symbolic DMS, showed no significant proactive interference effects from samples of prior trials. Instead, proactive interference was traceable to the probe value of the prior trial. Overall, the auditory DMS data for the dolphin were functionally similar to results reported for monkeys tested on symbolic, identity, and probe visual DMS tasks.     

Delayed matching of visual materials by a bottlenosed dolphin aided by auditory symbols

A bottlenosed dolphin (Tursiops truncatus) with good underwater and aerial visual acuity was tested in visual matching-to-sample (MTS) paradigms. Attempts to train visual identity MTS directly, using two simple two-dimensional patterns as sample stimuli and as alternatives (comparison stimuli), met with little success, in keeping with previously observed difficulties of this auditory-specialized species for learning complex tasks utilizing simple visual materials. Pairing of each visual sample with a unique sound, to produce a compound auditory-visual sample, while retaining the two visual alternatives, resulted in the dolphin’s learning both auditory-visual symbolic matching and visual-visual identity matching. At 0-sec delay, performance with the auditory element of the sample alone was equivalent (76%) to performance with the visual element alone; performance with the compound was distinctly better (95%–98% correct). Testing with longer delays using the visual element alone resulted in successful matching through to a maximum delay of 34 sec. These results provided the first demonstration of delayed MTS in a dolphin using visual materials, and complemented other data showing the ready capability of this species for delayedauditory MTS. It appeared that the dolphin solved the visual MTS task by forming auditory codes to represent the visual materials, and that these auditory codes were eventually replaced with purely visual codes.     

Monkey auditory list memory: tests with mixed and blocked retention delays

A rhesus monkey was tested in an auditory list memory task with blocked and mixed retention delays. Each list of four natural or environmental sounds (from a center speaker) was followed by a retention delay (0, 1, 2, 10, 20, or 30 sec) and then by a recognition test (from two side speakers). The monkey had been tested for 12 years in tasks with blocked delays. An earlier (4 years prior) blocked-delay test was repeated, with virtually identical results. The results from the mixed-delay test were likewise similar. Thus, the peculiarities of blocked-delay testing, such as delay predictability or differences in list spacing, apparently do not alter this monkey’s memory for auditory lists. It is concluded from this and other evidence that the monkey’s serial position functions reflect mnemonic processes that change with changes in retention delay and are not artifacts of the blocked-delay procedure. The nature of the monkey’s auditory memory is discussed.     

Basic auditory processing and developmental dyslexia in Chinese

The present study explores the relationship between basic auditory processing of sound rise time, frequency, duration and intensity, phonological skills (onset-rime and tone awareness, sound blending, RAN, and phonological memory) and reading disability in Chinese. A series of psychometric, literacy, phonological, auditory, and character processing tasks were given to 73 native speakers of Mandarin with an average age of 9.7 years. Twenty-six children had developmental dyslexia, 29 were chronological age-matched controls (CA controls) and 18 were reading-matched controls (RL controls). Chinese children with dyslexia were significantly poorer than CA controls in almost all phonological tasks, in semantic radical search, and in phonological recoding proficiency. Chinese children with dyslexia also showed significant impairments in most of the basic auditory processing tasks. Regression analyses demonstrated that different auditory measures of rise time discrimination were the strongest predictors of individual differences in Chinese character reading (1 Rise task) and phonological recoding (2 Rise task) respectively, with frequency discrimination also important for nonsense syllable decoding. Our results support the hypothesis that accurate perception of the amplitude envelope of speech is critical for phonological development and consequently reading acquisition across languages.     

“咽音海豚音”训练法在高校声乐教学中的应用

研究意大利美声唱法＂咽音海豚音＂发声训练方法,通过海豚音、狼鸣音发声科学原理,将意大利美声理论的经验形态教学提升到科学理论指导训练,将难以捕捉的抽象的声乐训练创新成简易、科学的训练法,应用于高校声乐教学。     

Infants'' Localization of Sounds within Hemifields: Estimates of Minimum Audible Angle

Infants' acuity in localizing sounds within hemifields was examined by determining the smallest sound shift off 60 degrees and along the horizontal axis that infants could discriminate reliably, that is, minimum audible angle (MAA). Infants 6, 12, and 18 months of age were tested using a Go/No-Go conditioned head-turn procedure in which infants received an equal number of no-change (control) trials and sound-shift (experimental) trials. A correct response (i.e., a head turn toward the loud-speakers) on an experimental trial resulted in visual reinforcement. Localization acuity for sounds within hemifields was fairly poor and improved systematically with increasing age. MAA estimates at each age were significantly higher, indicating poorer localization acuity, in comparison to those obtained previously in research examining infants' resolution of auditory space near midline. These findings are consistent with adult data and demonstrate a finer partitioning of auditory space near midline than within hemifields. The implications of these findings for our understanding of the development of auditory processing mechanisms in sound localization are discussed.     

Executive function and early reading skills

The purpose of this study was to examine how executive function skills in verbal and nonverbal auditory tasks are related to early reading skills in beginning readers. Kindergarteners (N = 41, aged 5 years) completed verbal (phonemes) and nonverbal (environmental sounds) Continuous Performance tasks yielding measures of executive function (misses, false alarms, and shift) as well as reaction time and D-Prime (sensitivity). Year-end measures of early reading skill included tests of phoneme awareness, letter knowledge, as well as reading (words and nonwords). The children made more errors on the verbal than the nonverbal tasks, suggesting that executive function abilities may differ by task. Adding to the literature on the role of inhibitory skills in reading, verbal inhibitory executive function skills were tied more closely to early reading than other verbal or nonverbal skills when age, short-term memory, and vocabulary were controlled.     

Auditory Frequency Resolution in Human Infancy

Frequency resolution is a fundamental capacity of the auditory system that underlies the perception of all complex sounds. The development of this capacity has not been well characterized in humans. This investigation used a nonsimultaneous pulsation threshold technique to examine the development of infant frequency resolution. Psychophysical tuning curves were obtained for 3- and 6-month-olds and for adults at either 500, 1,000, or 4,000 Hz. Both the sensation level and the sound pressure level of the stimulus were varied for adults to determine the contribution of stimulus intensity to age differences in frequency resolution. At 500 and 1,000 Hz, 3- and 6-month-olds' tuning curve widths were equivalent to adults'. At 4,000 Hz, the 3-month-olds' tuning curves were broader than those of 6-month-olds and adults, even when absolute sound pressure level was equivalent. The maturation of psychophysical frequency resolution in infants is discussed in terms of the general development of the auditory system and of nonsensory factors that might contribute to age differences in performance.     

Inhibition of delay of the two-way avoidance response and warning-signal salience

Effects of extended training (nine sessions, 50 trials each) on two-way avoidance response latencies were studied. For each rat, auditory and visual warning signals (CS) were presented on separate trials, either according to a Gellermann series or in 25-trial blocks. Intermittent presentation of the two kinds of trials yielded shorter latencies and higher levels of avoidance performance in response to the noise CS than in response to the darkness CS. Presentation of trials in blocks revealed stronger response-eliciting properties of stimuli presented during the second half of the session than of those presented during the first half. A significant decrease of avoidance performance in the early portions of the delay period, an index of inhibition of delay, was obtained on auditory trials presented in the second half of the sessions. Results indicate that strong fear of the warning signal is required for inhibition of delay of avoidance responses.     

Integration of cardiac responses to serial stimuli after Pavlovian conditioning in rats

The expression of cardiac responses to sequences of two sounds was studied in restrained rats following discriminative trace or delay conditioning. Stimuli paired with a tail shock 10 sec later (CS1) elicited conditioned bradycardia. Unpaired or neutral stimuli (CS0) elicited mostly tachycardia. Rats did not learn to suppress responding to nonreinforced sequences with an interval of 6 sec between sounds. Responses to the second stimulus were significantly augmented following a CS1 stimulus, but not following a CS0 stimulus. Real-time summation of simple responses provided a more complete and quantitative prediction of dual responses than did resetting or facilitation. These results extend the time range over which summation may be observed from less than 2 sec to at least 16 sec. They appear to be inconsistent with models involving competition between unitary representations of stimuli in short-term memory and suggest the existence of multiple stimulus traces with independent time courses.     

Potentiation of responding on a VR schedule by a stimulus correlated with reinforcement: Effects of diffuse and localized signals

In Experiment 1, rats were trained to leverpress on a variable ratio (VR) 30 schedule with a 500-msec delay between the reinforced response and food delivery. Subjects that experienced a signal during the delay responded faster than did control subjects that received the stimulus un-correlated with reinforcement. Higher response rates were obtained when the stimulus used to signal reinforcement was auditory rather than visual. Experiments 2 and 3 compared the effects of signaling reinforcement with either a localized or a diffuse light on responding maintained by VR schedules of reinforcement. Elevated response rates were observed with the diffuse stimulus, but the localized stimulus failed to produce such potentiation. Experiment 3 also examined the conditioned reinforcing power of localized and diffuse visual stimuli. These results are discussed with reference to (1) theories of selective association and sign tracking and (2) their implications for current theories of signaling reinforcement.     

In a daily time–place learning task,time is only used as a discriminative stimulus if each daily session is associated with a distinct spatial location

It is difficult for rats to acquire daily time–place (TP) learning tasks. One theory suggests that rats do not use time of day as a stimulus signaling a specific response. In the present study, we tested rats’ ability to use time of day as a discriminative stimulus. A fixed-interval procedure was used in which one lever provided reinforcement on a FI-5-s schedule in morning sessions, and the same lever provided reinforcement on a FI-30-s schedule in afternoon sessions. Because only one place was used in this paradigm, the rats could only use time of day to acquire the task. Mean responses during the first 5 s of the first trial in each session indicated that the rats did not discriminate between the two sessions. In Phase II, a different lever location was used for each of the two daily sessions, which meant that both spatial and temporal information could be used to acquire the task. The rats readily acquired the task in this phase, and probe trials indicated that the rats were using a combination of spatial and temporal information to discriminate between the two different trial types. When the spatial cue was removed in Phase III, rats no longer discriminated the two sessions, suggesting that time can only be used as a discriminative stimulus when each daily session is associated with a distinct spatial location.     

A possible contribution of word-retrieval difficulties to reading and spelling impairments

Good and poor readers at the junior high school level and good and poor spellers at the university level were compared on their ability to produce words in response to a semantic cue (a category name), a visual cue (three letters), and an auditory cue (a syllable rime). Kindergarten children were tested on a word-identification task and their retrieval of words in response to the semantic and auditory cues. At all ages, poor readers or spellers produced fewer words on all word-retrieval tasks than did good readers or spellers. Performance on the auditory and visual word-retrieval tasks correlated very highly with pseudoword reading and spelling ability in the two older groups; in the kindergarten children, auditory retrieval correlated with word identification. The results suggest that poor readers have not organized words in long-term memory according to rhyming families but that good readers have. We speculate that failure to retrieve rhyming words during acquisition of reading and spelling skills underlies the failure of poor readers and spellers to abstract the higher-order relationships between orthography and phonology.     

Short-term memory for visual and auditory stimuli in pigeons

Separate groups of pigeons were trained to perform symbolic delayed matching to sample with auditory and visual sample stimuli. For animals in the auditory group, ambient tones that varied in frequency served as sample stimuli; for animals in the visual group, ambient red and green lights served as sample stimuli. In both cases, the sample stimuli were mapped onto the yellow and blue comparison stimuli presented on left and right pecking keys. In Experiments 1 and 2, it was found that visual and auditory delayed matching were affected in the same ways by several temporal variables: delay, length of exposure to the sample stimulus, and intertrial interval. In Experiments 3, 4A, and 4B, a houselight presented during the delay interval strongly interfered with retention in both visual and auditory groups, but white noise presented during the delay had little effect in either group. These results seem to be more in line with a prospective memory model, in which visual and auditory sample stimuli are coded into the same instructional memories, than with a model based on concepts of retrospective memory and modality specificity.     

An investigation into teaching phonemic awareness through shared reading and writing

This study examined teaching phonemic awareness by embedding sound talk within meaningful literacy experiences of shared reading and writing. Small groups of 5 and 6-year-old children were seen three times a week for seven weeks. Four phonemic awareness tasks – first and last sound identification, sound segmentation and deletion – were targeted in each session, with scaffolding fitting task difficulty and individual child ability. Results showed that such naturalistic instruction lead to gains in phonemic awareness compared to a no-treatment control group for both the treatment group as a whole and for a subgroup of children with lower literacy levels. Treatment-specific improvement was evident in three of the four phonemic awareness tasks: first sound identification, last sound identification, and sound segmentation. Additional observations of language and literacy benefits for this emergent literacy approach were also identified.     

Poor performance on serial visual tasks in persons with reading disabilities: impaired working memory?

The present study investigates the performance of persons with reading disabilities (PRD) on a variety of sequential visual-comparison tasks that have different working-memory requirements. In addition, mediating relationships between the sequential comparison process and attention and memory skills were looked for. Our findings suggest that PRD perform worse than normally achieving readers (NAR) when the task requires more than a minimal amount of working memory, unrelated to presentation rate. We also demonstrate high correlations between performance on the task with the most working-memory demands and reading-related skills, suggesting that poor working-memory abilities may be one of the underlying mechanisms of dyslexia. The mediating model analysis indicates that order judgment tasks are mediating to verbal working memory, suggesting that visual sequence memory precedes auditory sequence memory. We further suggest that visual tasks involving sequential comparisons could probe for poor working memory in PRD.     

Memory for a stimulus versus anticipation of a response: Contrasting effects of proactive interference in two delayed comparison tasks

Pigeons were trained to perform two delayed comparison tasks that differed only in the temporal placement of the retention interval relative to the sample and comparison stimuli. In one task (conditional delayed response—CDR), the subject could determine the correct response prior to the retention interval. In the second task (delayed conditional response—DCR), the subject was required to compare stimuli presented before and after the retention interval. Although overt mediational responding was not observed in the CDR condition, retention was, nevertheless, greater than in the DCR condition. Furthermore, this difference was amplified at short intertrial intervals. Finally, retention in the DCR, but not the CDR, condition was disrupted by proactive interference (PI) from previous sample stimuli. The results suggest that memory is less closely tied to the sample stimulus when the stimuli necessary to determine the correct response are presented prior to the retention interval (CDR and other delayed response tasks) than when the subject must compare stimuli across the retention interval (DCR, or delayed matching-to-sample, tasks). This difference may lead directly, or indirectly through an interaction with PI, to task differences in retention.     

The Goldilocks Effect in Infant Auditory Attention

Infants must learn about many cognitive domains (e.g., language, music) from auditory statistics, yet capacity limits on their cognitive resources restrict the quantity that they can encode. Previous research has established that infants can attend to only a subset of available acoustic input. Yet few previous studies have directly examined infant auditory attention, and none have directly tested theorized mechanisms of attentional selection based on stimulus complexity. This work utilizes model‐based behavioral methods that were recently developed to examine visual attention in infants (e.g., Kidd, Piantadosi, & Aslin, 2012). The present results demonstrate that 7‐ to 8‐month‐old infants selectively attend to nonsocial auditory stimuli that are intermediately predictable/complex with respect to their current implicit beliefs and expectations. These findings provide evidence of a broad principle of infant attention across modalities and suggest that sound‐to‐sound transitional statistics heavily influence the allocation of auditory attention in human infants.     

Comparing cognition by integrating concept learning,proactive interference,and list memory

This article describes an approach for training a variety of species to learn the abstract concept of same/different, which in turn forms the basis for testing proactive interference and list memory. The stimulus set for concept-learning training was progressively doubled from 8, 16, 32, 64, 128 . . . to 1,024 different pictures with novel-stimulus transfer following learning. All species fully learned the same/different abstract concept: capuchin and rhesus monkeys learned more readily than pigeons; nutcrackers and magpies were at least equivalent to monkeys and transferred somewhat better following initial training sets. A similar task using the 1,024-picture set plus delays was used to test proactive interference on occasional trials. Pigeons revealed greater interference with 10-s than with 1-s delays, whereas delay time had no effect on rhesus monkeys, suggesting that the monkeys’ interference was event based. This same single-item same/different task was expanded to a 4-item list memory task to test animal list memory. Humans were tested similarly with lists of kaleidoscope pictures. Delays between the list and test were manipulated, resulting in strong initial recency effects (i.e., strong 4th-item memory) at short delays and changing to a strong primacy effect (i.e., strong 1st-item memory) at long delays (pigeons 0-s to 10-s delays; monkeys 0-s to 30-s delays; humans 0-s to 100-s delays). Results and findings are discussed in terms of these species’ cognition and memory comparisons, evolutionary implications, and future directions for testing other species in these synergistically related tasks.