The memory drum theory after twenty years

The difference between the Henry “memory-drum” theory and our version is that ours includes an additional assumption that, after programming has occurred, the resultant representation can be stored in short-term memory. Otherwise, the essential ideas are the same in the two theories. Implications of the presently available data for the distinction between the theories are discussed. Regardless of how one evaluates our added assumption, it is clear that the essential insight of the Henry theory has fared very well in the 20 yr since the theory first appeared in print.     

The memory drum theory after twenty years: comments on Henry's note

The difference between the Henry "memory-drum" theory and our version is that ours includes, an additional assumption that, after programming has occurred, the resultant representation can be stored in short-term memory. Otherwise, the essential ideas are the same in the two theories. Implications of the presently available data for the distinction between the theories are discussed. Regardless of how one evaluates our added assumption, it is clear that the essential insight of the Henry theory has fared very well in the 20 years since the theory first appeared in print.     

Simple reaction time as a function of response complexity: memory drum theory revisited

The prediction emanating from memory drum theory (Henry & Rogers, 1960') that simple reaction time (SRT) increases as a response becomes more complex (i.e., increases in number of movement parts) was investigated. Experiments 1 (N = 20) and 3 (N = 16) indicated that SRT was longer for responses consisting of two and three parts than it was for a one-part response and this may be interpreted as support for the prediction. Failing to support the prediction, however, was the finding that SRT was essentially the same for responses consisting of two and three parts. This may not be too damaging to the theory because it could simply be reflecting an upper limit in terms of numbers of parts or response duration for causing an increase in SRT. Experiments 2 (N = 20) and 3 revealed an SRT effect between two responses that were supposed to be equal in complexity. At first, this finding appeared to be contrary to the prediction, but it may be interpreted as support for it because one of the responses defined as having one movement part could actually have had two     

Visual short-term memory in the first year of life: capacity and recency effects.

A span task was developed to assess the amount of information infants could hold in short-term memory. In this task, infants were presented with up to 4 items in succession and then tested for recognition by successively pairing each item with a novel one. A large sample of full-terms and low-birth-weight preterms (< 1,750 g) was tested longitudinally, at 5, 7, and 12 months of age. Results were similar for both groups: (a) Longer spans were more difficult, especially at the 2 younger ages; (b) memory capacity increased over the 1st year of life--whereas less than 25% of the sample could hold as many as 3-4 items in mind at once at the younger ages, nearly half could do so by 12 months of age; (c) there was a marked recency effect (greater memory for the final item) for spans of 3 and 4 at all ages; and (d) there were modest cross-age correlations, indicating that individual differences in memory capacity showed some stability from age to age.     

Beating the memory drum: Rapid sequential visual presentation (RSVP) on a 4K PDP-8

A program for presenting alphanumeric strings in rapid succession on a Videoterminal is described. Rates of up to 30 items/sec can be obtained with relatively “slow” systems by creating a push-up stack in the terminal’s display memory and scrolling the items past a small display window during presentation. Advantages of such a program are discussed, and the system is compared to mechanical techniques of rapid sequential visual presentation.     

The perirhinal cortex and long-term familiarity memory.

To analyse the functions of the perirhinal cortex, the activity of single neurons in the perirhinal cortex was recorded while macaques performed a delayed matching-to-sample task with up to three intervening stimuli. Some neurons had activity related to working memory, in that they responded more to the sample than to the match image within a trial, as shown previously. However, when a novel set of stimuli was introduced, the neuronal responses were on average only 47% of the magnitude of the responses to the set of very familiar stimuli. Moreover, it was shown in three monkeys that the responses of the perirhinal cortex neurons gradually increased over hundreds of presentations (mean = 400 over 7-13 days) of the new set of (initially novel) stimuli to become as large as those to the already familiar stimuli. Thus perirhinal cortex neurons represent the very long-term familiarity of visual stimuli. Part of the impairment in temporal lobe amnesia may be related to the difficulty of building representations of the degree of familiarity of stimuli. A neural network model of how the perirhinal cortex could implement long-term familiarity memory is proposed using Hebbian associative learning.     

The relation between source memory and aging.

Previous research has shown that elderly adults have difficulty recalling the source of recently acquired facts but does not indicate whether source memory is more impaired than fact memory. This study examined old and young subjects' memory for novel facts that had been read to them by 1 of 2 experimental sources either in a random order or in a blocked order. When fact memory was equated in young and old at different levels of performance, the elderly exhibited disproportionate source memory deficits in the blocked condition but not in the random condition. Results suggest that the relation between fact and source memory in the elderly varies across experimental conditions.     

Remembering first impressions: Effects of intentionality and diagnosticity on subsequent memory

People rely on first impressions every day as an important tool to interpret social behavior. While research is beginning to reveal the neural underpinnings of first impressions, particularly through understanding the role of dorsal medial prefrontal cortex (dmPFC), little is known about the way in which first impressions are encoded into memory. This is surprising because first impressions are relevant from a social perspective for future interactions, requiring that they be transferred to memory. The present study used a subsequent-memory paradigm to test the conditions under which the dmPFC is implicated in the encoding of first impressions. We found that intentionally forming impressions engages the dmPFC more than does incidentally forming impressions, and that this engagement supports the encoding of remembered impressions. In addition, we found that diagnostic information, which more readily lends itself to forming trait impressions, engages the dmPFC more than does neutral information. These results indicate that the neural system subserving memory for impressions is sensitive to consciously formed impressions. The results also suggest a distinction between a social memory system and other explicit memory systems governed by the medial temporal lobes.     

The dynamics of memory retrieval in older adulthood.

One of the most robust findings in cognitive aging is that of a significant decline in self-initiated recall from episodic memory. In laboratory studies this deficit can be seen in significant age differences in word-list free recall. In this article, we focus on free recall of categorized word lists where one observes "response bursting" in the form of a rapid output of within-category items with longer delays between categories. Age differences appear primarily in between-category latencies, results that are consistent with a relative sparing of semantic memory combined with an age-deficit in episodic retrieval. When adjusted for differences in overall mnemonic ability, we demonstrate that the relationship between organization and learning remains invariant with normal aging. We argue that the locus of the age deficit in free recall lies at the level of temporal coding of items and the use of temporal associations to guide recall.     

The deterioration of semantic memory in Alzheimer's disease.

Semantic memory impairment is a common feature of dementia of the Alzheimer type (DAT). Recent research has shown that patients with DAT are more impaired (relative to non-demented controls) in generating exemplars from a particular semantic category (e.g., animals) than words beginning with a particular letter, exhibit an altered temporal dynamic during the production of category exemplars, are impaired on confrontation naming tasks and make predominantly superordinate or semantically related errors, consistently misidentify the same objects across a variety of semantic tasks, and have alterations in multi-dimensional scaling models of their semantic network that are indicative of a loss of concepts and associations. These results are consistent with the view that Alzheimer's disease results in a breakdown in the organization and structure of semantic knowledge as neurodegeneration spreads to the association cortices that presumably store semantic representations.     

The influence of implicit motives on memory processes.

Four studies tested the hypothesis that agentic and communal motives act as a channel for new knowledge and are linked to specific ways of organizing information that facilitate its accessibility. In Study 1, agentic and communal participants read an agentic or a communal vignette consisting of differentiated and integrated statements, performed a distraction task, then completed written recall and recognition tasks. Agentics recalled and recognized more differentiation in the agentic story; communals recalled and recognized more integration in the communal story. A computerized replication with randomized recognition items (Study 2) found the same pattern of recognition results. Studies 3 and 4 used implicit motive primes and found similar results in both written and computerized recognition tasks. These ways of organizing information have powerful implications for the encoding of autobiographical knowledge and its long-term organization.     

The role of short-term memory in semantic priming.

Two theories of priming were compared: spreading activation theories, in particular ACT, and compound-cue theories. Whereas ACT assumes that priming is a result of diffusing activation in long-term memory, compound-cue models suggest that priming results from a formation process of prime and target in short-term memory. Thirty-eight participants took part in a study that combined a digit span task with a double lexical decision task consisting of a prime and a target item. Digit span length (low, medium, and high) and prime type (related or unrelated word or nonword) were both within-subject variables. As expected, results showed significant priming effects. In favor of ACT, no interaction between digit span length and prime type was found. Additionally, a nonword inhibition effect (unrelated versus nonword prime) was found, which was predicted by compound-cue theories. This finding is discussed in terms of the process interference and response competition hypotheses.     

Measuring recognition memory.

Recent years have seen an expanded interest in recognition memory tasks. This resurgence of interest has also renewed concerns with measurement problems. Comparing 4 models of recognition memory, Snodgrass and Corwin (1988) found that measures of bias from the distribution-free (nonparametric) model were inadequate. However, their analysis was based on bias measures that can be shown a priori to be nonindependent of discrimination. This article traces the history of the nonparametric model and develops a better measure of bias. The consequence of developing this better measure is that the nonparametric model deserves serious consideration.     

The moral journey of the first Viennese psychoanalysts.

By exploring the cultural concerns of Freud's first Viennese disciples, this article explains how these concerns helped inspire both intellectual conviction in Freudianism and inner commitment to the psychoanalytic movement. In this way, it illuminates an important underlying identity between medical practitioners and laypersons within Freud's circle. At the same time, it brings to light the tension between values and science in Viennese psychoanalysis.     

The real relationship between short-term memory and working memory

Storage-oriented memory span tasks with no explicit concurrent processing are usually referred as short-term memory (STM) tasks, whereas tasks involving storage plus concurrent processing requirements are designated as working memory (WM) tasks. The present study explores a question that remains unsolved: Do STM and WM tasks clearly tap distinguishable theoretical constructs? For that purpose, a large sample of 403 participants was tested through 12 diverse memory span tasks. Half of those tasks are widely accepted as measures of STM, whereas the other half measure WM. The results show that STM and WM share largely overlapping underlying capacity limitations, suggesting that all memory span tasks tap essentially the same construct. Some implications are discussed.     

The intentionality of memory

In the philosophy of perception, typically, everything is illuminated. Discussions of perceptual experience primarily focus on subjects situated in illuminated environs. Rarely do we see treatment of putative perceptual experience involving darkness. In this paper, I will carefully canvas and characterize the nature of experiences of darkness, marking a substantive distinction between two such kinds of experiences. Crucially, I give an account of the distinctive phenomenology of experiences of darkness, and show that neither of the two broad kinds of experiences of darkness requires, as Roy Sorensen has recently suggested, the reification of unfamiliar entities to serve as objects of perceptual awareness. I will also offer potential candidates for the proper representational contents of experiences of darkness. This exploration not only reveals that such experiences pose no threat to a view like representationalism, but also demonstrates how experiences of darkness can be given their rightful place in a naturalistic theory of perceptual awareness. Atlast, darkness will be brought out from the shadows.

A dungeon horrible, on all sides round,

As one great furnace flamed, yet from those flames

No light; but rather darkness visible …

–John Milton, Paradise Lost     

The metasemantics of memory

In Sven Bernecker’s excellent new book, Memory, he proposes an account of what we might call the “metasemantics” of memory: the conditions that determine the contents of the mental representations employed in memory. Bernecker endorses a “pastist externalist” view, according to which the content of a memory-constituting representation is fixed, in part, by the “external” conditions prevalent at the (past) time of the tokening of the original representation (the one from which the memory-constituting one is causally derived). Bernecker argues that the best version of a pastist externalism about memory contents will have the result that there can be semantically-induced memory losses in cases involving unwitting “world-switching”. The burden of this paper is to show that Bernecker’s argument for this conclusion does not succeed. My arguments on this score have implications for our picture of mind-world relations, as these are reflected in a subject’s attempts to recall her past thoughts.