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R Ratcliff

Publications and source records attributed to R Ratcliff.

90 records · Page 5Linked to original sources
PubMed1986

Automatic activation of episodic information in a semantic memory task.

Four experiments are presented in which priming between newly learned associates and priming between well-known associates were examined in lexical decision. All four experiments found priming between newly learned associates, including conditions in which the Stimulus Onset Asynchrony (SOA) between prime and target was short (150 ms) and in which the probability was low (1/12) that the prime and target of a pair would be associated to each other. It was concluded, contrary to suggestions by Carroll and Kirsner (1982) and Tulving (1983), that newly learned associates can prime each other, and that they can do so at short SOAs.

Association Learning↗
PubMed1986

Inferences about predictable events.

If someone falls off of a 14th story roof, very predictably death will result. The conditions under which readers appear to infer such predictable outcomes were examined with three different retrieval paradigms: immediate recognition test, cued recall, and priming in word recognition. On immediate test, responses to a word representing the implicit outcome (e.g., dead) were slow, but on delayed test these responses were slow or inaccurate only when primed by an explicitly stated word. However, the word expressing the predictable outcome did function as an effective recall cue. Results suggest that readers encode these inferences into memory only minimally, but that they can make use of a cue word that represents the inference (e.g., dead) both at the time of an immediate test and in delayed cued recall.

Cognition↗
PubMed1986

Memory connections between thematically similar episodes.

Recent theories about the representation of thematic information in memory propose that two episodes that share a theme are connected together through a thematic structure. We investigated the use of such cross-episode connections in comprehension and memory in six experiments. Experiments 1 and 2 used a priming technique; it was found that verification time for a test sentence from one story was speeded by an immediately preceding test sentence from a thematically similar story but only when subjects were given instructions to rate the similarities of the stories. In the remaining experiments, a single test sentence was presented immediately after a story was read, with timing controlled by presenting the story one word at a time. Response time for a test sentence from a previously read story was facilitated if the immediately preceding story was thematically similar, but only if the previously read story was extensively prestudied. We conclude that, during reading of an episode, thematic information may be encoded so as to lead to activation of similar episodes and formation of connections in memory between episodes, but such encoding is not automatic and depends on subjects' strategies and task difficulty.

Adolescent↗
PubMed1986

A critical evaluation of the semantic-episodic distinction.

Tulving (1983, 1984) has recently claimed that a wide range of evidence supports the distinction between episodic and semantic memory systems. He has provided a list of features to describe the differences between the two systems and a set of experimental results to demonstrate the distinction. In this article, we present opposing evidence that invalidates many of the distinguishing features and contradicts interpretations of the supporting experiments. In addition, we argue that the question of whether there are two separate memory systems cannot be answered without a specific theory about the differences between the systems.

Amnesia↗
PubMed1986

More on the distinction between episodic and semantic memories.

In reply to a critique of the episodic/semantic distinction (McKoon, Ratcliff, & Dell, 1986), Tulving (1986) argues that the usual rules for testing theories do not apply to the classification of phenomena with respect to memory systems. But we respond that the classification methods proposed by Tulving (1986) may be detrimental to the advancement of theory and that whole domains of inquiry should not be excluded from the usual criteria of experimental psychology.

Brain↗
PubMed1985

Components of activation: repetition and priming effects in lexical decision and recognition.

Activation decay functions were examined in two different tasks: lexical decision and word recognition. Activation (amount of facilitation) was measured both for item repetition and for priming between newly learned associates. Results indicate that there are at least three different components of activation: a short-term component that decays with one or two intervening items and that appears to be common to priming and repetition; an intermediate component for repetition in recognition; and a long-term component for repetition.

Adolescent↗
PubMed1985

The role of semantic information in episodic retrieval.

In two experiments, subjects studied lists of categorized words and then were tested for recognition of those words. Response time for a test word was speeded whenever the immediately preceding test word was from the same category. This was true even for test words (lures) from categories never studied. Thus it is argued that semantic information not present at the time of study affected retrieval. This finding is discussed with respect to the distinction between episodic and semantic memories.

Adolescent↗
PubMed1984

The mental representation of knowledge acquired from maps.

Recognition priming and distance estimation were used to investigate the mental representation of knowledge acquired from maps. In Experiment 1, recognition priming showed that cities close in route distance primed each other more than cities far in route distance, even when Euclidean distance was equated. Experiment 2 showed that this finding was robust and not an artifact of the way subjects learned the maps. Distance estimations in Experiment 1 supported the priming results. These results indicated that psychological distance in cognitive maps is primarily dependent on route distance rather than Euclidean distance.

Cognition↗
PubMedDate not supplied

Design and application of NMR-compatible bioreactor circuits for extended perfusion of high-density mammalian cell cultures.

MR spectroscopy of cultured cells allows non-invasive analyses of the metabolism of cells with specific phenotypes under defined conditions. This technique can be used to investigate the intracellular metabolism of cells or extended to critically evaluate phenomena observed by in vivo MRS. In this paper, a cell maintenance system is described which allows MR analyses with unparalleled spectral resolution, S/N and stability. This system consists of a 25 mm diameter hollow fiber bioreactor and a supporting circuit. The hollow fiber reactor was chosen because it yields a large filling factor which can be perfused through defined volumes. The fibers were 300 microns diameter microporous (0.2 micron) cellulose acetate/cellulose nitrate membranes with high porosity, which allow bulk convective flow throughout the extracapillary space. This flow (Starling flow) is necessary to disrupt steady-state gradients in substrates and waste products. In many respects, the design of the supporting circuit is more important than the bioreactor itself, since it provides the reactor with the proper chemical and physical environment. Hence, this circuit can be applied to a variety of bioreactor configurations. The circuit consists of a hollow fiber oxygenator and a bleed-and-feed system housed in a temperature-controlled cabinet. Culture of mammalian cells in this reactor yields 31P spectra which have excellent spectral and temporal resolution. At confluence, endogenous 31P line widths were typically < 10 Hz (at 162 MHz) and well resolved spectra were obtained in < 30 s.

3T3 Cells↗