Mechanisms of aural encoding III: Distinctive features for vowels

To determine the processing of vowel sounds in short-term memory for a serial recall task, 100 Ss heard either a short string of isolated vowel sounds, or a string in which each of these same sounds was embedded between the consonants “h” and “d”. In contrast to findings by Wickelgren, neither an articulatory or an acoustic distinctive-feature analysis predicted the pattern of intrusion errors found. The overall recall of the different sounds was predicted by the ease with which they could be labelled for rehearsal. However, ease of labelling would not explain the pattern of intrusion errors, nor would any other analysis tried. These results are consistent with a coding model presented by Liberman et al (J967). Surprisingly, the patterns of intrusion errors were very similar whether the sounds were presented alone or embedded in words. The implications of these findings for distinctive feature theory and the encoding process are discussed.     

Distinctive feature codes in the short-term memory of children

The present studies investigated the use of distinctive feature codes in shortterm memory tasks by young, school-aged children. Each child was presented with 30 lists of consonant-vowel (CV) syllables for recall. In each list, the initial consonants were different, being drawn from the set of six English stop consonants. The data of interest were the errors in recall, which were not random as would be the case had the encoding unit been the entire consonantal phone. Rather the errors had distinctive features in common with the presented sound. Thus, children encode the consonantal phones into sets of unique features which are recalled independently at times.     

Mechanisms of aural encoding: VI. Consonants and vowels are remembered as subsets of distinctive features

An attempt was made to examine the manner in which consonants and vowels are coded in short-term memory. under identical recall conditions. Ss were presented with sequences of consonant-vowel digrams for serial recall. Sequences were composed of randomly presented consonants paired with/a/ or randomly presented vowels paired with /d/. Halle’s distinctive feature system was used to generate predictions concerning the frequency of intrusion errors. among phonemes. These predictions were based on the assumption that phonemes are discriminated in memory in terms of their component distinctive features, so that intrusions should most frequently occur between phonemes sharing similar distinctive features. The analysis of intrusion errors revealed that each consonant and vowel phoneme was coded m short-term memory by a particular combination of distinctive features which differed from one phoneme to another. A given phoneme was coded by the same set of distinctive features regardless of the number of syllables in the sequence. However, distinctive feature theories were not able to predict the frequency of intrusion errors for phonemes presented in the middle serial positions of a sequence with 100% accuracy. The results of the experiment support the notion that consonant and vowel phonemes are coded in a similar manner in STM and that this coding involves the retention of a specific set of distinctive features for each phoneme.     

Spatially Cued Retrieval of Sentences

Undergraduate Italian students studied a set of 16 feature markers that were either distributed across the areal domain of a map or listed next to the map outline. They then learned a series of 16 sentences in which subject nouns matched feature markers. Following learning, subjects either did or did not see the original features as they attempted to recall the stimulus sentences. In addition, control subjects heard the sentences and saw the map outline but did not see the feature markers. Subjects in the map-plus-features group who were cued at retrieval outperformed all other groups, especially on the second of two trials. The data support the conjoint retention hypothesis, which states that maps are stored as intact images and are then economically represented in working memory where the features serve as second stratum cues for the retrieval of related verbal information.     

Mechanisms of aural encoding: I. Distinctive features for consonants

To examine the importance of distinctive features that are used to encode consonants (following Wickelgren’s analysis) in an immediate recall task, sequences of 5 consonants, all paired with the vowel /a/ were constructed and presented aurally for recall. The middle three items in each sequence all had either the same place of articulation (front, middle, or back of the vocal apparatus), orthe same manner of articulation (voiced, unvoiced, or nasal), or were unrelated in either place or manner (control). It was shown that, in comparison with the control sequences, consonants imbedded among others articulated similarly were recalled less accurately, suggesting that these distinctive features are important in encoding and memory maintenance. A comparison of the 3 manner and 3 place features showed that the greatest difficulty in recall occurred for the similar manner sequences (especially voiced and unvoiced, implicating manner of articulation as the critical distinctive feature in aural encoding. Some discussion is also presented of a distinction between articulation and acoustic factors in encoding processes.     

Spatial Imagery Preserves Temporal Order

Line drawings were presented in either a spatial or a nonspatial format. Subjects recalled each of four sets of 24 items in serial order. Amount recalled in the correct serial order and sequencing errors were scored. In Experiment 1 items appeared either in consecutive locations of a matrix or in one central location. Subjects who saw the items in different locations made fewer sequencing errors than those who saw each item in a central location, but serial recall levels for these two conditions did not differ. When items appeared in nonconsecutive locations in Experiment 2, the advantage of the spatial presentation on sequencing errors disappeared. Experiment 3 included conditions in which both the consecutive and nonconsecutive spatial formats were paired with retrieval cues that either did or did not indicate the sequence of locations in which the items had appeared. Spatial imagery aided sequencing when, and only when, the order of locations in which the stimuli appeared could be reconstructed at retrieval.     

Effects of free and forced retrieval instructions on false recall and recognition.

One hundred undergraduates heard 6 lists of 14 words that were each associated with 1 of 6 central concepts not on the lists (the DRMRS procedure). The participants were instructed to recall as many words as possible (free retrieval) or to fill all 14 spaces (forced retrieval) and were subsequently given a recognition test. False recall and recognition of the critical central concepts were higher with forced than with free retrieval instructions, but correct recall and recognition were not affected. Confidence was lower for false than for correct recall and recognition. Confidence was also lower with forced than with free retrieval instructions for false recall but not for false recognition. The DRMRS procedure easily elicited false memories, but confidence judgments helped more in detecting them in recall than in recognition. Theoretical and applied implications are discussed.     

Misleading Suggestions can Alter Later Memory Reports even Following a Cognitive Interview

Taking an immediate recall test prior to misinformation exposure can increase eyewitness suggestibility—a finding termed retrieval‐enhanced suggestibility. Here, we examined whether retrieval‐enhanced suggestibility would occur when participants were administered an immediate Cognitive Interview (CI). The CI is an investigative interviewing technique that consistently elicits more correct details in memory reports than standard interviews. In this study, participants watched a video of a crime and then completed a distractor task (control condition), a free recall test, or the CI. They then heard misinformation presented in a narrative. Participants produced more accurate memory details in the CI than in free recall despite spending equal time on both tasks. However, the CI also increased the later report of misinformation relative to the control condition. These results show that initial retrieval can increase subsequent suggestibility even when such retrieval occurs under relatively ideal conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Identification versus discrimination of distinctive features in speech perception

Dichotically presented CV syllables were presented to 24 normal subjects under two contrasting performance requirements: consonant identification and consonant discrimination. In the identification task, subjects made more errors identifying stimuli distinguished by two as opposed to one distinctive feature. Conversely, in the discrimination task, subjects made more errors for stimuli distinguished by one as opposed to two distinctive features. It was proposed that the results of the identification task reflect the degree of information load in short-term memory. The results of the discrimination task, on the other hand, reflect the degree of perceptual similarity between contrasting stimuli. Both results were accounted for within a distinctive feature framework. Analyses of the individual features which comprised one and two feature distinctions demonstrated the perceptual prominence of the feature [voice] in contrast to the two place features [compact] and [grave].     

Effects of correspondence between encoding and retrieval organization in social memory

Memory research has shown impaired recall performance when a subset of the studied stimuli is presented at recall (the part-list cueing effect, Slamecka, 1968) or when the recall is collaborative (collaborative-inhibition effect, Weldon & Bellinger, 1997). In two experiments we explore these effects in an impression-formation context and compare two prominent accounts (retrieval blocking versus strategy disruption) for them. We varied the correspondence between item organization at encoding and retrieval, either by manipulating the organization of part-list cues (Experiment 1) or the organization of the stimulus list that was later recalled collaboratively (Experiment 2). Results showed that when encoding and recall organizations did not correspond recall was impaired, replicating part-list cueing and collaborative-inhibition effects. However, when encoding and retrieval organization corresponded, these effects were greatly reduced. Such results support the recall strategy disruption hypothesis and challenge the retrieval blocking account. Implications for understanding memory in a social context are discussed.     

Channel-capacity, intelligibility and immediate memory

When subjects try to remember lists of digits played to them through pulse-modulated white noise the number of errors they make is greater than would be expected if digitrecognition errors and immediate memory errors were independent (Exp. 1).

A second experiment compared recall of digits in early list positions, when digits in subsequent list positions were presented through noise, and in clear. Digits in early positions were less well remembered when digits in later list positions had to be discriminated through noise.

In a third experiment prose passages were played to subjects who subsequently answered questions about their factual content. Judged by this technique recall of the first half of a prose passage is less accurate if the second half must be heard through noise than if the entire passage is heard through a good fidelity system. These results together are interpreted as demonstrations that increased difficulty of recognition of speech through noise may interfere with other activities, (conveniently termed “rehearsal”) which may be necessary to efficiently retain data in memory.     

The importance of semantics in auditory representations

The purpose of the present study was to examine the nature of auditory representations by manipulating the semantic and physical relationships between auditory objects. On each trial, listeners heard a group of four simultaneous sounds for 1 sec, followed by 350 msec of noise, and then either the same sounds or three of the same plus a new one. Listeners completed a change-detection task and an object-encoding task. For change detection, listeners made a same-different judgment for the two groups of sounds. Object encoding was measured by presenting probe sounds that either were or were not present in the two groups. In Experiments 1 and 3, changing the target to an object that was acoustically different from but semantically the same as the original target resulted in more errors on both tasks than when the target changed to an acoustically and semantically different object. In Experiment 2, comparison of semantic and acoustic effects demonstrated that acoustics provide a weaker cue than semantics for both change detection and object encoding. The results suggest that listeners rely more on semantic information than on physical detail.)     

Are space and time automatically integrated in episodic memory?

The aim of the present study was to determine to what extent spatial and temporal features are automatically integrated during encoding in episodic memory. Both nameable and non-nameable stimuli were presented sequentially at different locations on a computer screen. Mixed and pure blocks of trials were used. In the mixed blocks participants were instructed to focus either on the spatial or the temporal order of the objects, as on the majority of the trials recall of this feature was tested (expected trials). However, on a few trials participants had to reproduce the other feature (unexpected trials). In the pure blocks either the spatial or the temporal order of the objects was tested on all trials. More errors were made on unexpected than on expected trials of the mixed blocks. Moreover, no primacy or recency effects were found when performance on the spatial task was plotted as a function of the temporal position. These results suggest that spatial information and temporal order information rely on separate encoding processes.     

Are space and time automatically integrated in episodic memory?

The aim of the present study was to determine to what extent spatial and temporal features are automatically integrated during encoding in episodic memory. Both nameable and non-nameable stimuli were presented sequentially at different locations on a computer screen. Mixed and pure blocks of trials were used. In the mixed blocks participants were instructed to focus either on the spatial or the temporal order of the objects, as on the majority of the trials recall of this feature was tested (expected trials). However, on a few trials participants had to reproduce the other feature (unexpected trials). In the pure blocks either the spatial or the temporal order of the objects was tested on all trials. More errors were made on unexpected than on expected trials of the mixed blocks. Moreover, no primacy or recency effects were found when performance on the spatial task was plotted as a function of the temporal position. These results suggest that spatial information and temporal order information rely on separate encoding processes.     

Comparison of the efficacy of two name-learning techniques: expanding rehearsal and name-face imagery

Two name-learning techniques were compared: expanding rehearsal and name-face imagery. Participants studied name-face associations and were given a cued recall test in which they were presented with a face and were to recall the name. They were presented with either an expanding rehearsal schedule (expanding condition), a distinctive facial feature coupled with a word phonologically similar to the last name and an interactive image linking the name and facial feature (name-face imagery condition), or a no memory (control) strategy. The expanding rehearsal schedule led to superior name learning relative to the name-face imagery and control conditions after a 15-min (Experiment 1) or 48-hr (Experiment 2) retention interval. In Experiment 3, the retrieval practice explanation was tested but not supported; we argue that an encoding variability interpretation is consistent with the overall pattern of results. Applied implications are also discussed.     

Semantic and acoustic processing in free and cued recall by educable mentally retarded adolescents

The abilities of educable mentally retarded adolescents to encode and retrieve words with semantic and acoustic cues were investigated in a free and cued recall task. On each of three trial blocks, seven groups of subjects were presented 20 unrelated stimulus words. Groups received either semantic, acoustic, or no encoding cues along with the stimuli. Free recall was requested from all subjects, followed immediately by a second period of either free recall or cued recall with the semantic or acoustic cues. Semantic cues were most effective when presented both at encoding and retrieval. The subjects were unable to use acoustic information as effective retrieval aids. Results were discussed in terms of encoding dimension dominance and mediational deficiencies.     

Large auditory and small visual effects in the recall of consonant letters

Eighty-six adults serially recalled lists of visually presented consonant letters similar in auditory or visual features or dissimilar in both feature sets. There were significantly more errors at every auditory list position than at the corresponding visual and neutral list positions, which did not themselves differ. There was a positive correlation between the tendency toward phonetic coding and overall performance, with 75 subjects making more errors on the auditory list than either of the other lists. The eight subjects who made more errors on the visual list showed poor performance in the recall of all lists. Factors governing the perceivability of stimuli apparently do not continue to operate significantly in controlling their recallability, at least in the case of veridical visual input.     

Listening for mispronunciations: A measure of what we hear during speech

Ss heard a passage from Lewis Carroll’s Through the Looking Glass and were asked to indicate, as quickly as possible, whenever they heard a mispronunciation. Mispronunciations were produced by changing one consonant sound in a three-syllable word by one, two, or four distinctive features (e.g., busily to “pizily,” “visily,” or “sizily”). Mispronunciations involving a single feature change were seldom detected, while two and four feature changes were readily detected. The syllable in which a mispronunciation occurred did not affect the probability of detecting a mispronunciation. However, reaction times to mispronounced words were at least a third of a second slower when they occurred in the-first syllable of the word. The results were taken to support the notion that words are identified by their distinctive features.     

Hypnosis and interrogative suggestibility

An attempt was made to induce memory errors through the use of misleading questioning in hypnosis. Subjects heard a short newslike story and gave initial free recall for the story details, then 4 days later were given three free recall trials: prior to hypnosis, following hypnotic induction and suggestion for enhanced memory, and after hypnosis was terminated. During hypnosis subjects were also twice interrogated with either misleading or objective questions for the story details. Accurate memory increased over the three free recall trials for all subjects regardless of hypnotizability. In recognition testing, subjects given misleading questions during the interrogation gave fewer correct responses, had more errors-in-fact as well as forgetting, and showed an increase in yielding to interrogative suggestibility over trials than subjects given objective questions. All subjects subsequently confabulated more information on the final awake free recall trial as a result of errors introduced during hypnotic interrogation process. These results help to clarify the inherent dangers in relying on hypnosis to enhance memory.     

Similarity and contrast in memory for relations

The paper reports four experiments concerned with memory for sets of categorically related or unrelated nouns, as a function of the extent to which initial processing focused on categorical or distinctive features of the nouns. The general finding is that distinctive features are valuable for later intracategory discrimination in recall and recognition, but categorical features are not, as judged by cued recall, recognition, measures of association between items, and categorical intrusion errors. A theoretical framework, based on the diagnostic value of features for various classifications, is offered as an account of the results.