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R Ratcliff

Publications and source records attributed to R Ratcliff.

At least 55 records · Page 3Linked to original sources
PubMed1995

Bias in the priming of object decisions.

Seven experiments examined priming effects for 3-dimensional line drawings in the object decision task. One of the most important previous findings about object decisions has been that the decision about a possible object is primed by previous presentation of the object, but the decision about an impossible object is not. Through the use of manipulations that can eliminate processes that retrieve episodic information (response time deadlines, memory load, forced choice, and similarity), equal size effects on impossible and possible objects were obtained. This is interpreted to mean that priming effects reflect a bias to respond "possible," which can be opposed for impossible objects by episodic information so as to yield the approximately null priming effect for impossible objects found in past experiments.

Decision Making↗
PubMed1995

Sequential effects in lexical decision: tests of compound-cue retrieval theory.

According to compound-cue retrieval theories, responses in lexical decision are determined by a passive process that matches a compound of the items in short-term memory against all of the information in long-term memory. Because responses depend on other items in short-term memory in addition to the target item about which a lexical decision is required, compound-cue theories must predict sequential effects and priming effects. For example, a nonword preceding a target should slow responses to the target, and a prime word related to a target word can affect responses to the target even when another item intervenes between them. In this article, the results of 4 experiments are presented and sequential effects are shown to be in accord with compound-cue theory.

Adult↗
PubMed1995

The application of Fourier deconvolution to reaction time data: a cautionary note.

The Fourier transform method in conjunction with frequency domain smoothing techniques has been suggested as a powerful tool for examining components in a serial, additive reaction time model (P. L. Smith, 1990). Robustness and sensitivity to violations of the assumptions of serial model of this method are evaluated. When an incorrect distribution was used in recovering an unobserved component, results gave no information to show that an incorrect distribution was used, and the results were just as interpretable as those obtained using the correct distribution. These results demonstrate that the assumptions underlying the method cannot be assessed by the result of deconvolution, and the method cannot show that the purported component is actually from the serial combination.

Fourier Analysis↗
PubMed1995

Generation and characterization of a delta F508 cystic fibrosis mouse model.

We have generated mice carrying the most common mutation in cystic fibrosis (CF), delta F508, within the cystic fibrosis (Cftr) gene. Mutant animals show pathological and electrophysiological changes consistent with a CF phenotype. delta F508-/- mice die from peritonitis and show deficiencies in cAMP-activated electrogenic Cl- transport. These mice produce delta F508 transcripts and show the temperature-dependent trafficking defect first described for the human delta F508 CFTR protein. A functional CFTR Cl- channel not demonstrated by null CF mice or present at 37 degrees C was detected following incubation of epithelial cells at 27 degrees C. Thus, these mice are an accurate delta F508 model and will be valuable for testing drugs aimed at overcoming the delta F508 trafficking defect.

Animals↗
PubMed1995

How should implicit memory phenomena be modeled?

In a reply to R. Ratcliff and G. McKoon's (1995a) article on bias in the object decision task, D. L. Schacter and L. A. Cooper (1995) critiqued their theoretical arguments and presented an updated view of priming in the object decision task. In the present article, the updated view is examined in detail, and it is questioned whether Schacter and Cooper's explanation of the data is sufficiently articulated to be falsifiable. It is also argued in the present article that evidence from other research domains is not directly supportive of the memory systems hypothesis and that the statistical power available in data from object decision experiments is not great enough to test some relevant hypotheses. Finally, the bias hypothesis (Ratcliff & McKoon, 1995a) is elaborated to show that it requires a particular pattern of experimental results and that it serves as a target phenomenon for modeling.

Decision Making↗
PubMed1994

Ion-transporting activity in the murine colonic epithelium of normal animals and animals with cystic fibrosis.

Electrogenic ion transport in the isolated colonic epithelium from normal and transgenic mice with cystic fibrosis (CF mice) has been investigated under short-circuit current (Isc) conditions. Normal tissues showed chloride secretion in response to carbachol or forskolin, which was sensitive to the Na-K-2Cl cotransport inhibitor, frusemide. Responses to both agents were maintained for at least 12 h in vitro, but the responses to carbachol changed in format throughout this period. By contrast CF colons failed to show the normal secretory responses to carbachol and forskolin, most preparations showing a decrease in Isc that was immediately reversed by frusemide. In CF colons addition of Ba2+ ions or tetraethylammonium (TEA+) to the apical bathing solution antagonised the reduction in Isc caused by the secretagogues. It is concluded that the reduction in Isc in CF colons is due to electrogenic K+ secretion and this was confirmed by flux studies using rubidium-86. In normal colons exposed to TEA+ the responses to forskolin were greater, but not significantly so, presumably because the minor K(+)-secretory responses are dominated by major chloride-secretory responses. Again rubidium-86 fluxes showed an increase of K+ secretion in normal colons receiving forskolin. Since the amiloride-sensitive current was not different in CF and normal colons there was no evidence that the CF mice were stressed in a way that increased mineralocorticoid levels and hence K+ secretion. Knowledge of the phenotype of the colonic epithelium of the CF mouse sets the baseline from which attempts at gene therapy for the gut must be judged.

Amiloride↗
PubMed1994

Empirical generality of data from recognition memory receiver-operating characteristic functions and implications for the global memory models.

The experiments presented in this article examined the slope of the zeta-ROC (receiver-operating characteristic) function for recognition memory. The slope was examined as a function of strength and the variables study time, list length, word frequency, and category membership. For normal distributions of familiarity, the slope of the zeta-ROC is the ratio of the new-item to old-item standard deviations. R. Ratcliff, C.-F. Sheu, and S. D. Gronlund (1992) found that the slope was constant within standard error as a function of strength of encoding, which is inconsistent with the predictions of the global memory models. The results presented here extend this finding: The slope was constant as a function of strength of encoding, list length, and the number of related items from a category in the study list. Word frequency did affect the slope, but within a frequency class the slope was constant as a function of strength. The implications of these data for the global memory models, the attention likelihood model, and variants of these models are discussed.

Attention↗
PubMed1994

Retrieving information from memory: spreading-activation theories versus compound-cue theories.

McNamara (1992a) attacked compound-cue theories on a number of grounds. Using free association as a measure of distance between concepts in memory, he argued that compound-cue theories cannot explain mediated priming effects. The authors show that free-association production probabilities do not accurately predict priming effects, either directly or in the context of current spreading-activation models, and so remove the basis for McNamara's criticism. McNamara also claimed that compound-cue theories cannot account for the sequential effects of items that precede a target on responses to the target, but the authors show that sequential effects are consistent with compound-cue models if the target item is weighted more heavily than preceding items in the calculation of familiarity that determines response time and accuracy for the target. It is concluded that, although compound-cue and spreading-activation theories are both consistent with available data, the compound-cue theory, having less freedom, has passed more stringent tests.

Attention↗
PubMed1994

Testing theories of language processing: an empirical investigation of the on-line lexical decision task.

On-line lexical decision has been used to test major theoretical hypotheses about language comprehension. Contrary to several current models, A. Sharkey and N. Sharkey (1992) found that a word in a sentence did not give facilitation to an immediately following, highly associated test item. In this article it is shown that such facilitation can be obtained. Other theories have proposed that syntactic processes supply antecedents for implicit anaphors. In using a test item that was an associate of the antecedent of the anaphor, the authors were unable to replicate previous findings of facilitation at but not before the site of the anaphor. Across 9 experiments, obtaining facilitation depended on the choice of control condition. This dependency raises questions about previous on-line lexical decision results that have been used to support the immediacy of syntactic processing.

Cognition↗
PubMed1994

Chloride secretion in response to guanylin in colonic epithelial from normal and transgenic cystic fibrosis mice.

1. Guanylin, a 15 amino acid endogenous gut peptide, increased the short circuit current (SCC) in the epithelium of the mouse colon, but only when applied to the apical and not the basolateral surface. 2. By use of selective blockers of epithelial ion transport and modification of the bathing solution, it was concluded that guanylin increased electrogenic chloride secretion but also had a minor effect on electrogenic sodium absorption. In addition there were small residual currents which remained unresolved. 3. The threshold concentration of guanylin causing a SCC increase was less than 50 nM, but at concentrations 40 times greater no indication of a maximally effective concentration was found. 4. Two guanylin isomers with the same amino acid sequence but with the disulphide bridges joined in an alternate fashion showed no activity. Thus only guanylin with the greatest structural homology to heat stable enterotoxin (STa) showed biological activity. 5. The action of guanylin was virtually eliminated in colonic epithelia from transgenic cystic fibrosis (CF) mice. As these animals lack the chloride channel coded by the CF gene sequence, it is likely that the final effector process in murine colonic epithelia involves the CFTR (cystic fibrosis transmembrane conductance regulator) chloride channel. 6. Opportunistic infections of the gut generating STa lead to diarrhoeal conditions via an action of the toxin on apical guanylin receptors. Thus, as discussed, the CF heterozygote may have a genetic advantage in this circumstance.

Amino Acid Sequence↗
PubMed1994

Kinin-stimulated chloride secretion in mouse colon requires the participation of CFTR chloride channels.

The effect of lysylbradykinin on electrogenic chloride secretion in the epithelium of the mouse colon has been investigated. The peptide was active only when applied to the basolateral surface and its effects were inhibited by the B2 receptor antagonist, Hoe 140, also applied to the same surface. The chloride channel blocker, niflumic acid, also inhibited the response to kinin when added apically. Cyclo-oxygenase inhibition with piroxicam attenuated the responses to kinin, indicating involvement of prostaglandins in the responses. It is concluded that lysylbradykinin increases chloride secretion by acting via B2 receptors and, as with other tissues, brings about secretion through the agency of multiple messengers. In colonic epithelia from cystic fibrosis (CF) mice lysylbradykinin was without effect, suggesting that the final effector process involves apically located cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels.

Animals↗
PubMed1994

Sentential context and on-line lexical decision.

J. L. Nicol and D. Swinney (1989) reported that lexical decision response times to a test word that was related to the implicit object of a verb were faster, when tested immediately after the verb, than response times to a control test word. They concluded from this result that the relation between the implicit object and the verb was understood during comprehension. In G. McKoon, R. Ratcliff, and G. Ward (1994), another interpretation was suggested, that the faster lexical decision response times were due to the better semantic-pragmatic fit of the related test words to the sentential contexts, and experimental data were presented to support this interpretation. In response, J.L. Nicol, J. D. Fodor, and D. Swinney (1994) pointed out some possible problems with these experiments. The experiment presented in this article undermines their arguments. By using sentences in which there was no implicit object, exactly the same pattern of results was found as originally reported by J. L. Nicol and D. Swinney, thereby implicating some factor other than syntactic processing of an implicit object as an explanation of their finding.

Cognition↗
PubMed1993

Correction of the ion transport defect in cystic fibrosis transgenic mice by gene therapy.

Cystic fibrosis (CF) is a lethal inherited disorder affecting about 1 in 2,000 Caucasians. The major cause of morbidity is permanent lung damage resulting from ion transport abnormalities in airway epithelia that lead to mucus accumulation and bacterial colonization. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that encodes a cyclic-AMP-regulated chloride channel. Cyclic-AMP-regulated chloride conductances are altered in airway epithelia from CF patients, suggesting that the functional expression of CFTR in the airways of CF patients may be a strategy for treatment. Transgenic mice with a disrupted cftr gene are appropriate for testing gene therapy protocols. Here we report the use of liposomes to deliver a CFTR expression plasmid to epithelia of the airway and to alveoli deep in the lung, leading to the correction of the ion conductance defects found in the trachea of transgenic (cf/cf) mice. These studies illustrate the feasibility of gene therapy for the pulmonary aspects of CF in humans.

Animals↗
PubMed1993

Inactivation of the murine cftr gene abolishes cAMP-mediated but not Ca(2+)-mediated secretagogue-induced volume decrease in small-intestinal crypts.

The cellular volume of crypts isolated from 2- to 3-week-old mouse small intestine has been measured to assess the capacity of the epithelial cells to respond to secretagogues. Vasoactive intestinal polypeptide (VIP) or carbachol, respectively cAMP- and calcium-mediated secretagogues, produced a reduction crypt volume attributed to KCl loss through channels activated by the agonists. Consistent with the participation of separate chloride channels, 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) blocked the carbachol- but not the VIP-induced volume decrease, whilst glibenclamide abolished the VIP effect without affecting the carbachol-induced volume decrease. Animals homozygous for a disrupted cftr gene, introduced by gene targeting, were also used as the source for crypt isolation. In these CFTR (-/-) crypts. VIP failed to elicit any reduction in cellular volume, while the response to carbachol was indistinguishable from that seen in crypts from age-matched control animals. These results are consistent with murine CFTR being a cAMP-activated chloride channel inhibited by glibenclamide and resistant to DIDS. A separate chloride conductance activated by calcium mobilization in small-intestinal crypts appears to be independent of CFTR.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

Discourse models, pronoun resolution, and the implicit causality of verbs.

Some interpersonal verbs, such as admire and amaze, describe an action or property of one person (the reactor) that is necessarily a response to an action or property of another (the initiator). We hypothesized that these verbs make the initiator relatively more accessible in a comprehender's discourse model and that this change in relative accessibility aids identification of the referent of a pronoun in a subsequent because clause. We predicted that, as a result, subjects would be faster to recognize a character's name after a because clause that uses a pronoun to refer to that character than after one that refers to some other character. Four experiments confirmed this prediction. Three further experiments demonstrated the importance of the verb's causal structure and of the presence of the connective because to this result.

Adult↗
PubMed1993

Methods for dealing with reaction time outliers.

The effect of outliers on reaction time analyses is evaluated. The first section assesses the power of different methods of minimizing the effect of outliers on analysis of variance (ANOVA) and makes recommendations about the use of transformations and cutoffs. The second section examines the effect of outliers and cutoffs on different measures of location, spread, and shape and concludes using quantitative examples that robust measures are much less affected by outliers and cutoffs than measures based on moments. The third section examines fitting explicit distribution functions as a way of recovering means and standard deviations and concludes that unless fitting the distribution function is used as a model of distribution shape, the method is probably not worth routine use.

Analysis of Variance↗
PubMed1993

TODAM and the list-strength and list-length effects: comment on Murdock and Kahana (1993a).

B. B. Murdock and M. J. Kahana (1993a) presented a continuous memory version of the theory of distributed associative memory (TODAM) model; they claimed that this model predicts list-strength and list-length findings, including those reported by R. Ratcliff, S. E. Clark, and R. M. Shiffrin (1990) and K. Murnane and R. M. Shiffrin (1991a). This model is quite similar to one discussed by R. M. Shiffrin, R. Ratcliff, and S. Clark (1990), who rejected the model on the basis of its inability to predict both an absent or negative list-strength effect (when strength is varied by repetitions) and a present list-length effect. In this comment we elaborate the earlier discussion and demonstrate that the version of TODAM proposed by B. B. Murdock and M. J. Kahana (1993a) indeed fails for this reason. We show this first for a somewhat simplified version of the model for which derivations are obvious and then in a simulation of the complete version using the parameter values suggested by B. B. Murdock and M. J. Kahana (1993a).

Female↗