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Biomedical subjects

A M Jacobs

Publications and source records attributed to A M Jacobs.

At least 19 recordsLinked to original sources
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

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↗
PubMed1992

Opioid receptor affinity for agonist-antagonist analgesics.

Analgesic medications are distributed to a variety of receptors within the central nervous system. Activity at these receptors (mu 1, mu, sigma, delta, kappa) results in both the beneficial pain-relieving effects of analgesics as well as undesirable side effects. The mixed agonist-antagonist class of analgesics offers the potential benefit of greater receptor site selectivity while diminishing the incidence of adverse sequelae, such as respiratory depression. Traditionally, it has been suggested that mixed agonist-antagonist medications may be associated with decreased analgesic effectiveness. However, newer agents of this mixed class may result in effective analgesia while diminishing the incidence of side effects.

Analgesics, Opioid↗
PubMed1992

An alternative approach to the mandatory year of clinical residency training.

The author takes the position that a mandatory fifth postgraduate year to serve as a uniform period of clinical education for podiatric medical graduates is unnecessary. A need exists to define primary podiatric medicine as the entry level podiatric medical field of practice. The colleges of podiatric medicine are urged to deemphasize podiatric surgery while placing greater emphasis on primary podiatric care. The author believes that the colleges are responsible for preparing primary podiatric medical practitioners. Residency programs should focus on specialty training in podiatric surgery and podiatric orthopedics.

Clinical Clerkship↗
PubMed1991

The effects of target discriminability and retinal eccentricity on saccade latencies: an analysis in terms of variable-criterion theory.

Two experiments are reported that studied changes in saccade latencies (SLs) in a target-identification task as a function of target discriminability and eccentricity. SLs were found to be longer when target discriminability was low and eccentricity was large, both factors showing a significant interaction. Variable-criterion theory (Grice, 1968) was used to derive a working model of the perceptual and decisional processes influencing SLs in the present task. Application of the measurement operations of the theory provided a good quantitative description of individual SL distributions. The analyses in terms of variable-criterion theory suggest that the perceptual process influencing SLs starts earlier and operates at a faster rate when the saccade target can be discriminated on the basis of global-visual features (e.g., size) than when local features (e.g., gaps) have to be extracted.

Adult↗
PubMed1991

The search operating characteristic as a tool for analyzing performance in dynamic visual search tasks.

A standard data plot for the analysis of eye movement behavior in visual search and related tasks, a Search Operating Characteristic (SOC), is proposed. The SOC plots mean fixation duration (in ms) vs. search span (in items/fixation) for different difficulty levels. It is well specified by a reciprocal power function and this function can be explained with the help of Piéron's law.

Eye Movements↗
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↗
PubMed1991

Synovectomy-arthroplasty as an alternative to triple arthrodesis in the management of subtalar joint pain.

Subtalar joint synovectomy-arthroplasty represents an intermediate intervention between more traditional conservative and surgical techniques. Localization of pathology to the structures of the subtalar joint is essential. The likelihood of operative success is predicted by a prolonged remission of symptoms following the injection of steroid and local anesthesia within the subtalar joint. The procedure reduces pain and swelling while increasing ambulatory capacity. No appreciable increase in subtalar joint motion occurs.

Arthrodesis↗
PubMed1991

Posterior calcaneal osteotomy. Effect, technique, and indications.

Posterior calcaneal osteotomy is a technically simple procedure that may be used to correct frontal, transverse, or sagittal plane displacement of the calcaneus associated with flatfoot deformity. In selected individuals, subluxation about the oblique axis of the midtarsal joint may be stabilized. Forefoot supinatus may be expected to reduce secondary to the reduction of heel valgus obtained, although with deformity chronicity, adaptive midtarsal joint changes may necessitate medial column stabilization. Posterior calcaneal osteotomy increases rotational stability of the subtalar joint in a supinatory direction. In addition, displacement of the posterior calcaneal fragment effects a dynamic correction force by translocation of the Achilles tendon and its posterior relation to the axis of the subtalar joint.

Calcaneus↗
PubMed1990

Local antibiotic treatment of soft tissue and bone infections of the foot.

Twenty-seven pedal soft tissue and bone infections in 26 patients were treated with surgical necrectomy of infected tissues and implantation of antibiotic-loaded polymethyl methacrylate bone cement beads on chains. The definitive diagnosis of the infected tissues was obtained by culture and histologic examination in all of the cases. A wide variety of foot infections was successfully treated in this manner. The success rate without recurrence of osteomyelitis or soft tissue infection was 95% in this study at an average of 16 months after surgery.

Adult↗
PubMed1990

Development and application of antibiotic-loaded bone cement beads.

The authors presented an overview of the development of antibiotic-loaded bone cement beads and their indications for usage, method of application, advantages, disadvantages, and causes of failure. This method of treatment for bone and soft tissue infections of the foot is not a panacea and should be used only in selected cases. The vascular status and the physiologic ability of the patient to heal a peripheral wound or infection are the basis for the success of this method of therapy. European literature makes little mention of adjunctive systemic antibiotic therapy with local antibiotic-loaded bone cement bead use. It is the authors' opinion that clinical judgment should be used to determine the necessity for such therapy.

Anti-Bacterial Agents↗
PubMed1990

Use of antibiotic-loaded bone cement in the management of common infections of the foot and ankle.

Antibiotic-loaded bone cement is a useful adjunct in the management of chronic osteomyelitis and in the prevention of recurrent osteomyelitis after an initial attack. Additionally, antibiotic-loaded bone cement stimulated the formation of granulation tissue in excess of that which would normally be expected. Our experience has been consistent with others' experience, which suggests that the use of antibiotic-loaded bone cement is an effective means of reducing the length of hospitalization and the cost usually associated with traditional methods in the management of bone and soft-tissue infections.

Adolescent↗
PubMed1989

Sensory factors are insufficient to define the ocular saccade goal in complex visual fields.

In most normal visual search situations, the environment is filled with a variety of stimuli, and selection among possible saccade targets is necessary. Current theories of visuomotor mechanisms must take into account not only the classical 'retinal error' input signal, but also perceptual and decisional factors as well as task-specific strategies adopted by the subjects. Experiments are reported in which eye movements are recorded in tasks requiring ocular saccades to be made onto target letters indicated by a peripherally visible mark or embedded within lines of homogeneous background letters. The results show how nonsensory factors interact with visual determinants in the preparation of the exploratory saccades. Expectations concerning the visibility of the sought-for target influence the spatial and temporal parameters of the eye movement which will be executed.

Attention↗
PubMed1989

Eye movement control during reading: II. Frequency of refixating a word.

An analysis of over 40,000 eye fixations made by college students during reading indicates that the frequency of immediately refixating a word following an initial eye fixation on it varies with the location of that fixation. The refixation frequency is lowest near the center of the word, positively accelerating with distance from the center. The data are well fit by a parabolic function. Assuming that refixation frequency is related to the frequency of successful word identification, the observed curvilinear relation results naturally from models that postulate a linear decrease in visual information with retinal eccentricity. A single letter difference in fixation location in a word can make a sizeable difference in the likelihood of refixating that word. The effects of word length and cultural frequency on the frequency of refixating are also examined.

Adult↗
PubMed1989

On the role of competing word units in visual word recognition: the neighborhood frequency effect.

Current models of word recognition generally assume that word units orthographically similar to a stimulus word are involved in the visual recognition of this word. We refer to this set of orthographically similar words as an orthographic neighborhood. Two experiments are presented that investigate the ways in which the composition of this neighborhood can affect word recognition. The data indicate that the presence in the neighborhood of at least one unit of higher frequency than the stimulus word itself results in interference in stimulus word processing. Lexical decision latencies (Experiment 1) and gaze durations (Experiment 2) to words with one neighbor of higher frequency were significantly longer than to words without a more frequent neighbor. This neighborhood frequency effect is discussed in terms of the different types of candidate selection process postulated by contemporary models of visual word recognition.

Adult↗
PubMed1989

Thermographic evaluation of the autonomic effects of nerve blocks in the foot.

The authors evaluated regional skin temperatures of the foot following the administration of a variety of local anesthetic nerve blocks with either Xylocaine (lidocaine hydrochloride) or Sensorcaine (bupivacaine hydrochloride). The study was carried out on ten randomized parallel groups of five subjects, each group being tested with one drug and one regional nerve block. The results indicated that both Xylocaine and Sensorcaine, when administered as a posterior tibial block, result in a significantly increased blood flow to the foot. Nerve blockade of the remaining nerves of the foot did not significantly increase the sympatholytic effect obtained by posterior tibial nerve block alone.

Adult↗