Memory as embodiment : the case of modality and serial short-term memory

Classical explanations for the modality effect—superior short-term serial recall of auditory compared to visual sequences—typically recur to privileged processing of information derived from auditory sources. Here we critically appraise such accounts, and re-evaluate the nature of the canonical empirical phenomena that have motivated them. Three experiments show that the standard account of modality in memory is untenable, since auditory superiority in recency is often accompanied by visual superiority in mid-list serial positions. We explain this simultaneous auditory and visual superiority by reference to the way in which perceptual objects are formed in the two modalities and how those objects are mapped to speech motor forms to support sequence maintenance and reproduction. Specifically, stronger obligatory object formation operating in the standard auditory form of sequence presentation compared to that for visual sequences leads both to enhanced addressability of information at the object boundaries and reduced addressability for that in the interior. Because standard visual presentation does not lead to such object formation, such sequences do not show the boundary advantage observed for auditory presentation, but neither do they suffer loss of addressability associated with object information, thereby affording more ready mapping of that information into a rehearsal cohort to support recall. We show that a range of factors that impede this perceptual-motor mapping eliminate visual superiority while leaving auditory superiority unaffected. We make a general case for viewing short-term memory as an embodied, perceptual-motor process

The company a word keeps: the role of neighbourhood density in verbal short-term memory

Psycholinguistic information plays an important role in verbal memory over the short-term (vSTM). One such linguistic feature is neighbourhood density (ND)—the number of words that can be derived from a given word by changing a single phoneme or single letter—so that vSTM performance is better when word sequences are from dense rather than sparse neighbourhoods, an effect attributed to higher levels of supportive activation among neighbouring words. Generally, it has been assumed that lexical variables influence item memory but not order memory, and we show that the typical vSTM advantage for dense neighbourhood words in serial recall is eliminated when using serial recognition. However, we also show that the usual effect of ND is reversed—for both serial recall and serial recognition—when using a subset of those same words. The findings call into question the way in which ND has been incorporated into accounts of vSTM that invoke mutual support from long-term representations on either encoding or retrieval

Questioning short-term memory and its measurement: why digit span measures long-term associative learning

Traditional accounts of verbal short-term memory explain differences in performance for different types of verbal material by reference to inherent characteristics of the verbal items making up memory sequences. The role of previous experience with sequences of different types is ostensibly controlled for either by deliberate exclusion or by presenting multiple trials constructed from different random permutations

Long-term associative learning predicts verbal short-term memory performance

Studies using tests such as digit span and nonword repetition have implicated short-term memory across a range of developmental domains. Such tests ostensibly assess specialized processes for the short-term manipulation and maintenance of information that are often argued to enable long-term learning. However, there is considerable evidence for an influence of long-term linguistic learning on performance in short-term memory tasks that brings into question the role of a specialized short-term memory system separate from long-term knowledge. Using natural language corpora, we show experimentally and computationally that performance on three widely used measures of short-term memory (digit span, nonword repetition, and sentence recall) can be predicted from simple associative learning operating on the linguistic environment to which a typical child may have been exposed. The findings support the broad view that short-term verbal memory performance reflects the application of long-term language knowledge to the experimental setting

Does short-term memory develop?

Such is the consistency by which performance on measures of short-term memory (STM) increase with age that developmental increases in STM capacity are largely accepted as fact. However, our analysis of a robust but almost ignored finding – that span for digit sequences (the traditional measure of STM) increases at a far greater rate than span for other verbal material – fundamentally undermines the assumption that increased performance in STM tasks is underpinned by developmental increases in capacity. We show that this digit superiority with age effect is explained by the relatively greater linguistic exposure to random sequences of digits versus other stimuli such as words. A simple associative learning process that learns incrementally from exposure to language accounts for the effect, without any need to invoke an STM mechanism, much less one that increases in capacity with age. By extension, using corpus data directed at 2-3 year old children, 4-6 year old children, and adults, we show that age-related performance increases with other types of verbal material are equally driven by the same basic associative learning process operating on the expanding exposure to language experienced by the child. Our results question the idea that tests such as digit span are measuring a dedicated system for the temporary maintenance and manipulation of verbal material, and as such have implications for our understanding of those aspects of typical and atypical development that are usually accounted for with respect to the operation of such a system

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Implant Programs for Feedlot Heifers using Synovex® Plus™, Revalor®-H, or Finaplix®-H with MGA

A commercial feedlot experiment was conducted using 1,558 heifers to evaluate the effects of implant programs on finishing heifers. Implanting with Synovex Plus increased ADG and hot carcass weight compared to heifers implanted with Revalor-H or Finaplix- H and fed MGA. Heifers implanted with either Synovex Plus or Revalor-H had increased DMI compared to heifers implanted with Finaplix-H. Marbling score was influenced by each of the implant treatments, being highest for Finaplix-H followed by Revalor-H and Synovex Plus

Implant Programs for Feedlot Heifers Using Synovex® Plus™

Two commercial feedyard experiments evaluated implant strategies for feedlot heifers. In both experiments, implanting heifers with Synovex Plus increased ADG compared to heifers implanted with Finaplix-H and fed MGA. In Experiment 1, implanting heifers with Synovex Plus improved feed conversion and increased live basis net returns, and the use of MGA with Synovex Plus increased carcass merit basis net returns and had similar marbling scores compared with Finaplix-H and MGA

Limitless capacity: a dynamic object-oriented approach to short-term memory

The notion of capacity-limited processing systems is a core element of cognitive accounts of limited and variable performance, enshrined within the short-term memory construct. We begin with a detailed critical analysis of the conceptual bases of this view and argue that there are fundamental problems – ones that go to the heart of cognitivism more generally – that render it untenable. In place of limited capacity systems, we propose a framework for explaining performance that focuses on the dynamic interplay of three aspects of any given setting: the particular task that must be accomplished, the nature and form of the material upon which the task must be performed, and the repertoire of skills and perceptual-motor functions possessed by the participant. We provide empirical examples of the applications of this framework in areas of performance typically accounted for by reference to capacity-limited short-term memory processes

Language and short-term memory : the role of perceptual-motor affordance

The advantage for real words over nonwords in serial recall—the lexicality effect—is typically attributed to support for item-level phonology, either via redintegration, whereby partially degraded short-term traces are “cleaned up” via support from long-term representations of the phonological material or via the more robust temporary activation of long-term lexical phonological knowledge that derives from its combination with established lexical and semantic levels of representation. The much smaller effect of lexicality in serial recognition, where the items are re-presented in the recognition cue, is attributed either to the minimal role for redintegration from long-term memory or to the minimal role for item memory itself in such retrieval conditions. We show that the reduced lexicality effect in serial recognition is not a function of the retrieval conditions, but rather because previous demonstrations have used auditory presentation, and we demonstrate a robust lexicality effect for visual serial recognition in a setting where auditory presentation produces no such effect. Furthermore, this effect is abolished under conditions of articulatory suppression. We argue that linguistic knowledge affects the readiness with which verbal material is segmentally recoded via speech motor processes that support rehearsal and therefore affects tasks that involve recoding. On the other hand, auditory perceptual organization affords sequence matching in the absence of such a requirement for segmental recoding and therefore does not show such effects of linguistic knowledge