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J Grainger

Publications and source records attributed to J Grainger.

At least 37 records · Page 2Linked to original sources
PubMed1995

The incremental priming technique: a method for determining within-condition priming effects.

A novel priming technique is applied in two experiments using an alphabetic decision and a lexical decision task to study effects of repetition, and form-related priming on letter and word recognition. The incremental priming technique consists of a gradual increase of the prime's informational value (operationalized as prime intensity). The minimum prime-intensity level serves as a within-condition baseline for each priming condition. Thus, we can define any priming effect with respect to two baseline conditions: one is the minimum-intensity condition of the particular priming condition (within-condition baseline), and the other is a different priming condition (across-condition baseline). This double-baseline approach makes measuring of priming effects more reliable and imposes stronger constraints on our interpretations of these effects.

Arousal↗
PubMed1994

Field-amplified sample stacking in micellar electrokinetic chromatography for on-column sample concentration of neutral molecules.

On-column concentration of neutral molecules was achieved for the first time in micellar electrokinetic chromatography by means of field-amplified sample stacking. The stacking process was accomplished by dissolving the neutral analytes in a low-concentration micellar solution that was still above the critical micelle concentration. The lower total ionic strength in the sample buffer compared to the electrophoresis buffer allowed the negatively charged micelles to migrate rapidly into the boundary between the sample and the running buffer where they slow down. This field-amplified sample stacking was achieved by using normal or reversed electrode polarity and produced a 75-85-fold increase in sensitivity for 1,2,4,7- and 1,2,4,8-tetrachlorodibenzo-p-dioxins. The peak area counts obtained from the sample stacking process were proportional to the sample volume injected, and the stacking efficiency was dependent on the micellar concentration. The best stacking efficiency was obtained when the micelle concentration was slightly higher than the critical micelle concentration. When the injection volume was relatively small, the normal-polarity stacking procedure produced a higher stacking efficiency. However, when the injection volume was large, reversed polarity produced a higher stacking efficiency because the non-uniform distribution of the electrical field strength had been eliminated.

Chromatography↗
PubMed1994

Effects of orthography are independent of phonology in masked form priming.

Briefly presented forward-masked primes that share letters with a word target have been shown to facilitate performance in different word recognition tasks. However, in all the experiments that have previously reported these facilitatory effects, related primes not only shared more letters with the target than did unrelated primes (orthographic priming), but they also shared more phonemes (phonological priming). The stimuli used in the present experiments allow us to separate out the effects of orthographic priming from phonological priming. Varying prime exposure duration from 14 to 57 msec, it is shown that effects of orthography follow a distinct time-course from the effects of phonology, and that orthographic facilitation does not result from a confound with phonological prime-target overlap.

Humans↗
PubMed1994

Chemical characterization and disposition studies with 1,2,7,8-tetrabromodibenzofuran in the rat.

Polybrominated dibenzo-p-dioxins and dibenzofurans have been identified as potential environmental contaminants. The present studies were designed to characterize the chemical disposition of a tetrabrominated dibenzofuran. The isomer-specific pattern of 1,2,7,8-tetrabromodibenzofuran (TBDF) was chemically characterized using high-pressure liquid chromatography, gas chromatography/mass spectrometry, infrared absorption, and proton nuclear magnetic resonance techniques. The absorption, distribution, and elimination of 1,2,7,8-[4,6-3H]-TBDF were examined in the rat following a single oral, dermal, or intravenous dose of 1 nmol/kg. The 1,2,7,8-TBDF was rapidly excreted in the bile (approximately 50% of the dose in 8 h). Likewise, over half of the administered dose was found in the feces and intestine contents 24 h after iv administration and in feces 72 h after oral administration. Thus, the half-life of 1,2,7,8-TBDF is approximately 1 d. Major tissue depots included the liver, adipose tissue, and skin. The decline in hepatic concentrations observed in the iv and bile studies occurred in conjunction with metabolic elimination as well as a slight accumulation in adipose tissue. Dermal absorption of 1,2,7,8-TBDF, quantified as the amount contained in tissues (excluding the skin site) and excreta at 72 h, was estimated to be 29% of the administered dose. Thus, the general disposition profile of 1,2,7,8-TBDF in the rat is similar to that of other polyhalogenated aromatic hydrocarbons. Due to its rapid elimination, which is consistent with its predicted susceptibility to metabolic elimination, acute exposure to 1,2,7,8-TBDF would not be expected to result in the degree of toxicity associated with other more persistent congeners.

Absorption↗
PubMed1994

A study of masked form priming in picture and word naming.

We report a series of picture- and word-naming experiments in which the masked priming paradigm with prime exposures brief enough to prevent prime identification were used. Experiment 1 demonstrates that the prior presentation of the same word prime facilitates both picture and word naming independently of target frequency. In Experiments 2 and 3, primes that were pseudohomophones of picture targets produced facilitatory effects compared with orthographic controls, but these orthographically similar nonword primes did not facilitate picture naming compared with unrelated controls. On the other hand, word targets were primarily facilitated by orthographic prime-target overlap. This marked dissociation in the priming effects obtained with picture and word targets is discussed in relation to different explanations of masked form priming effects in visual word recognition and current models of picture and word naming.

Attention↗
PubMed1993

Masked partial-word priming in visual word recognition: effects of positional letter frequency.

In 4 primed lexical decision experiments, it was found that the positional frequencies of letters shared by the prime and target relative to the overall positional letter frequency of the target determined the magnitude of priming effects. The lower the positional frequency of shared letters, the stronger the facilitatory effect observed. Both an interactive and noninteractive semistochastic version of the interactive activation model captured the principal trends in the data. It is argued that masked partial-word priming arises from a tradeoff between the facilitation generated by prime-target letter overlap and the inhibition generated from all lexical representations activated by letters in the prime that receive further support on target presentation.

Adult↗
PubMed1992

Testing a semistochastic variant of the interactive activation model in different word recognition experiments.

A semistochastic variant of the interactive activation (IA) model of context effects in letter perception (McClelland & Rumelhart, 1981) was used to simulate response time distributions and means in different experiments investigating the effects of word frequency, neighborhood size and frequency, and orthographic priming in visual word recognition. The results provide evidence in favor of the connectivity assumption underlying the model but question the necessity of the interactivity assumption for simulating latencies in word recognition tasks. Together with those of a recent study by McClelland (1991), the present results suggest that 10 years after its appearance, the IA model's potential for testing hypotheses about the structure and dynamics of basic phenomena of human information processing in a variety of perceptual and cognitive tasks is not yet fully exploited.

Arousal↗
PubMed1992

Phonology and orthography in visual word recognition: evidence from masked non-word priming.

Three lexical decision experiments in French investigated the effects of briefly presented forward-masked non-word primes on latencies to phonologically and/or orthographically related targets. At 64-msec prime presentation durations, primes that are pseudohomophones of the target produced facilitatory effects compared to orthographic controls, but these orthographically similar non-word primes did not facilitate target recognition compared to unrelated controls. These results were obtained independently of target word frequency and independently of the presence or absence of pseudohomophone targets in the experimental lists. With a 32-msec prime duration, on the other hand, pseudohomophone and orthographic primes had similar effects on target recognition, both producing facilitation relative to unrelated controls. The results are discussed in terms of the time course of phonological and orthographic code activation in the processing of pronounceable strings of letters.

Adult↗
PubMed1992

Neighborhood frequency effects and letter visibility in visual word recognition.

Two experiments are described that measured lexical decision latencies and errors to five-letter French words with a single higher frequency orthographic neighbor and control words with no higher frequency neighbors. The higher frequency neighbor differed from the stimulus word by either the second letter (e.g., ASTRE-AUTRE) or the fourth letter (CHOPE-CHOSE). Neighborhood frequency effects were found to interact with this factor, and significant interference was observed only to CHOPE-type words. The effects of neighborhood frequency were also found to interact with the position of initial fixation in the stimulus word (either the second letter or the fourth letter). Interference was greatly reduced when the initial fixation was on the critical disambiguating letter (i.e., the letter P in CHOPE). Moreover, word recognition was improved when subjects initially fixated the second letter relative to when they initially fixated the fourth letter of a five-letter word, but this second-letter advantage practically disappeared when the stimulus differed from a more frequent word by its fourth letter. The results are interpreted in terms of the interaction between visual and lexical factors in visual work recognition.

Adult↗
PubMed1991

Prescribed fenoterol and death from asthma in New Zealand, 1981-7: a further case-control study.

The association between inhaled fenoterol and death from asthma has been investigated further by studying 112 asthma deaths (cases) during 1981-7 in patients aged 5-45 years who had been admitted to a major hospital for asthma during the 12 months before death. Two age matched control groups were chosen. Control group A comprised 427 patients who had been admitted to hospital for asthma during the calendar year that the corresponding death occurred and who had also had a previous admission for asthma in the previous 12 months. Control group B comprised 448 patients admitted to hospital for asthma during the calendar year in which the admission of the corresponding case occurred. The inhaled fenoterol odds ratio was 2.11 (95% confidence interval (CI) 1.37-3.23, p less than 0.01) when group A was used as the control (the approach used in previous studies), and 2.66 (95% CI 1.74-4.06, p less than 0.01) with group B as the control (the approach recommended by critics of previous studies). Markers of chronic asthma severity were associated with asthma death when control group B was used, but not when control group A was used (which indicates that these markers were indirectly matched for when control group A was used). Information was also collected on various markers of acute asthma severity and prescription of psychotropic drugs, but it was found that these were not important confounders. These findings address the major criticisms of previous case-control studies of this issue, and add support to the hypothesis that inhaled fenoterol increases the risk of death in patients with severe asthma.

Administration, Inhalation↗
PubMed1991

Automatic letter priming in an alphabetic decision task.

An alphabetic decision task was used to study effects of form priming on letter recognition at very short prime durations (20 to 80 msec). The task required subjects to decide whether a stimulus was a letter or a nonletter. Experiment 1 showed clear facilitatory effects of primes being either physically or nominally identical to the targets, with a stable advantage for the former. Experiment 2 demonstrated that uppercase letters are classified more rapidly as letters (vs. non-letters) when they are preceded by a briefly exposed, forward- and backward-masked, visually similar uppercase letter than when they are preceded by a visually dissimilar uppercase letter. Finally, Experiment 3 demonstrated that nominally identical and visually similar primes facilitate processing more than do nominally identical, visually dissimilar primes. The alphabetic decision task proved to produce sensitive and stable priming effects at the feature, letter, and response-choice level. The present results on letter-letter priming thus constitute a solid data base against which to evaluate other priming effects, such as word-letter priming. The results are discussed in light of current activation models of letter and word recognition and are compared with data simulated by the interactive activation model (McClelland & Rumelhart, 1981).

Arousal↗
PubMed1990

A comparison of the haemodynamic and hypokalaemic effects of inhaled pirbuterol and salbutamol.

In this double blind study, the cardiovascular and hypokalaemic effects of equal doses of inhaled pirbuterol and salbutamol were compared in eight healthy volunteers. Increasing doses of 200, 400, 600 and 800 micrograms (total dose 2000 micrograms) were given from a metered dose inhaler at 15 min intervals, followed by measurement of heart rate, blood pressure, total electromechanical systole (QS2I) (as a measure of inotropic response) and plasma potassium (K+) concentration 15 min after each inhalation. After inhalation of the highest concentration, salbutamol resulted in a greater increase in heart rate (10.5 bpm vs 4.4 bpm, p less than 0.0007), and reduction in QS2I (-25.4 ms vs -9.6 ms, p less than 0.0001) than pirbuterol. There were no significant differences in changes in systolic blood pressure (1.9 mmHg vs 6 mmHg, p = 0.27), diastolic blood pressure (-5.8 mmHg vs -3.9 mmHg, p = 0.64) or plasma K+ (-0.21 mmol/L vs -0.15 mmol/L, p = 0.57). We conclude that the new beta-2 adrenergic agonist pirbuterol is at least as beta-2 selective as salbutamol when administered by repeated inhalation in healthy volunteers.

Administration, Inhalation↗
PubMed1990

Gas chromatographic and spectral properties of pentafluorobenzyl derivatives of 2,4-dichlorophenoxyacetic acid and phenolic pesticides and metabolites.

Eleven phenols and 2,4-dichlorophenoxyacetic acid, compounds that may be found in body fluids of humans exposed to pesticides, are derivatized with pentafluorobenzyl bromide and characterized by gas chromatography with electron capture detection. These derivatives are further characterized by positive and negative chemical ionization mass spectrometry, nuclear magnetic resonance spectroscopy, and gas chromatography-Fourier transform infrared spectroscopy. Negative chemical ionization mass spectra of all derivatives have an anionic base peak derived from the parent analyte. In the positive mode the nonchlorinated derivatives have base peaks indicative of the analyte, while chlorinated derivatives are cleaved to give the pentafluorobenzyl cation as base peak. The possibility is explored that ortho-substituted phenols might be formed as byproducts in these derivatizations.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1990

Case-control study of prescribed fenoterol and death from asthma in New Zealand, 1977-81.

A previous New Zealand case-control study of asthma deaths in the 5-45 year age group during 1981-3 found that prescription of fenoterol (by metered dose inhaler) was associated with an increased risk of death in patients with severe asthma. One major criticism of this study was that drug data for the cases and controls came from different sources. A new case-control design has been used to evaluate the same hypothesis, with a different set of asthma deaths, the same source for drug information being used for both cases and controls. This depended on identifying deaths from asthma during 1977-81 from national mortality records, and ascertaining which patients from those who died had been admitted to a major hospital for asthma during the 12 months before death. The study was confined to this subgroup, which accounted for about 20% of all asthma deaths in the areas served by a major hospital. For each of the eligible patients who died four age matched controls were selected from patients admitted to hospital for asthma during the year that the death occurred who had also had an admission for asthma in the previous 12 months. For the 58 cases and 227 control subjects information on prescribed drugs was collected from the hospital records relating to the previous admission. The odds ratio of asthma death in patients prescribed inhaled fenoterol was 1.99 (95% confidence interval 1.12-3.55, p = 0.02). As in the previous study, subgroups defined by markers of chronic asthma severity were also considered. The inhaled fenoterol odds ratio was 2.98 (95% CI 1.15-7.70, p = 0.02) in patients prescribed three or more categories of asthma drugs, 3.91 (95% CI 1.79-8.54, p less than 0.01) in patients with a previous admission for asthma in the past 12 months, and 5.83 (95% CI 1.62-21.0, p = 0.01) in patients prescribed oral corticosteroids at the time of admission. In patients with the most severe asthma (defined by a previous admission for asthma during the past 12 months and prescribed oral corticosteroids at time of admission) the inhaled fenoterol odds ratio was 9.82 (95% CI 2.23-43.4, p less than 0.01). These findings add further support to the hypothesis that inhaled fenoterol increases the risk of death in patients with severe asthma.

Administration, Inhalation↗
PubMed1990

Neighborhood frequency effects in visual word recognition: a comparison of lexical decision and masked identification latencies.

Recent research suggests that the time to recognize a visually presented word may be a function of the frequencies of orthographically similar words. More precisely, recognition latencies and errors appear to increase significantly as soon as the stimulus word is orthographically similar to at least one other higher frequency word. This phenomenon, referred to as the neighborhood frequency effect, was subjected to further experimental testing, using a larger selection of words of varying frequency and length, and using a new experimental technique that proved to be extremely sensitive to such effects. The results provide additional support for earlier observations of neighborhood frequency effects. It is also demonstrated that clear word-frequency effects do obtain when neighborhood frequency is held constant. The results support activation-based accounts of the word-recognition process.

Attention↗
PubMed1990

Priming word recognition with orthographic neighbors: effects of relative prime-target frequency.

Four lexical decision experiments were performed with an orthographic priming paradigm in which test words were preceded by orthographically related or unrelated prime words. When prime words were presented for 350 ms without a mask, it was observed that primes that are lower frequency orthographic neighbors of the target interfered with target processing relative to an unrelated condition. When primes were higher frequency neighbors of the target, no interference or facilitation was observed. On the other hand, with briefly presented masked primes, interference was observed with higher frequency prime words. Finally, facilitatory effects in masked repetition priming were obtained with both high- and low-frequency prime-target pairs. The results are interpreted in terms of activation and selection processes operating in visual word recognition.

Adult↗