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F Gobet

Publications and source records attributed to F Gobet.

29 records · Page 2Linked to original sources
PubMed1998

Expert chess memory: revisiting the chunking hypothesis.

After reviewing the relevant theory on chess expertise, this paper re-examines experimentally the finding of Chase and Simon (1973a) that the differences in ability of chess players at different skill levels to copy and to recall positions are attributable to the experts' storage of thousands of chunks (patterned clusters of pieces) in long-term memory. Despite important differences in the experimental apparatus, the data of the present experiments regarding latencies and chess relations between successively placed pieces are highly correlated with those of Chase and Simon. We conclude that the two-second inter-chunk interval used to define chunk boundaries is robust, and that chunks have psychological reality. We discuss the possible reasons why Masters in our new study used substantially larger chunks than the Master of the 1973 study, and extend the chunking theory to take account of the evidence for large retrieval structures (templates) in long-term memory.

Adolescent↗
PubMed1996

Templates in chess memory: a mechanism for recalling several boards.

This paper addresses empirically and theoretically a question derived from the chunking theory of memory (Chase & Simon, 1973a, 1973b): To what extent is skilled chess memory limited by the size of short-term memory (about seven chunks)? This question is addressed first with an experiment where subjects, ranking from class A players to grandmasters, are asked to recall up to five positions presented during 5 s each. Results show a decline of percentage of recall with additional boards, but also show that expert players recall more pieces than is predicted by the chunking theory in its original form. A second experiment shows that longer latencies between the presentation of boards facilitate recall. In a third experiment, a Chessmaster gradually increases the number of boards he can reproduce with higher than 70% average accuracy to nine, replacing as many as 160 pieces correctly. To account for the results of these experiments, a revision of the Chase-Simon theory is proposed. It is suggested that chess players, like experts in other recall tasks, use long-term memory retrieval structures (Chase & Ericsson, 1982) or templates in addition to chunks in short-term memory to store information rapidly.

Humans↗
PubMed1996

Recall of random and distorted chess positions: implications for the theory of expertise.

This paper explores the question, important to the theory of expert performance, of the nature and number of chunks that chess experts hold in memory. It examines how memory contents determine players' abilities to reconstruct (1) positions from games, (2) positions distorted in various ways, and (3) random positions. Comparison of a computer simulation with a human experiment supports the usual estimate that chess Masters store some 50,000 chunks in memory. The observed impairment of recall when positions are modified by mirror image reflection implies that each chunk represents a specific pattern of pieces in specific location. A good account of the results of the experiments is given by the template theory proposed by Gobet and Simon (in press) as an extension of Chase and Simon's (1973b) initial chunking proposal, and in agreement with other recent proposals for modification of the chunking theory (Richman, Staszewski, & Simon, 1995) as applied to various recall tasks.

Adolescent↗
PubMed1995

Use of a digestive mucosal graft in urethroplasty. An experimental study--prospective utilization of the appendix mucosa.

Colic mucosa was used as a graft for urethral construction in 9 Sprague-Dawley rats. A urethrectomy was performed in each rat and then a urethroplasty built with the colic mucosa taken from a segmental colectomy. After 6 weeks to 3 months, all of these rats developed a typical urothelium. The digestive mucosa has been transformed into urothelium or acts as a stent to guide regrowth from each end. These results are encouraging, but the use of the appendix mucosa for hypospadias repair and for urethroplasty deserves further study.

Animals↗
PubMed1995

[Urethroplasty using appendiceal mucosa. A preliminary study of urethroplasty using free colonic mucosa in rats].

The use of skin, buccal or vesical mucosa for free graft urethroplasties is associated with a high incidence of postoperative stenosis and fistulas. In order to develop a new urethral substitute, the appendicular mucosa is proposed as a new material. As animals do not possess an appendix, an animal model of colonic mucosa urethroplasty was used in this study. Forty rats were submitted to distal segmental urethrectomy. For 14 rats, a simple urethral catheter was inserted without urethroplasty (group I), for 7 rats, urethroplasty was performed using a collagen tube (group II), and for 19 rats, a free colonic mucosa urethroplasty was performed (Group III). After 3 to 6 weeks, a microscopic and macroscopic study was performed. A newly formed urethra was only observed in the last group (Group III). Histological examination visualized a typical non-secreting urothelium. In the light of this study, free gastrointestinal mucosa appears to be suitable for urethroplasties. Until a human clinical application is developed, early histological studies will probably help to explain the development of this neo-urothelium, which remains hypothetical at the present time.

Animals↗
PubMed1994

[Free appendix mucosa urethroplasty. A preliminary experimental study of free grafts of digestive tract mucosa].

The various tissues used as free grafts in urethroplasties are associated with a high incidence of fistulae and strictures. The search for a new, more effective substitute has led the authors to study the possibility of using a new type of mucosa: appendicular mucosa. The size and cylindrical structure of the appendix and its easy resection make it an original and adapted urethral substitute. As most animals do not possess an appendix, an animal model of subcutaneous free graft of colonic mucosa was studied. Segmental transverse colonectomy was performed in 16 rats. The mucosa was stripped and then grafted subcutaneously. Three to six weeks after the operation, this mucosa was still perfectly viable in 11 rats. Its fixation ensures a better take of the graft. Histological examination revealed that the epithelium retained the features of gastrointestinal mucosa: monostratified, pavement and secretory. The results of this preliminary study are very encouraging and justify continuation of experimental studies of free appendicular mucosal urethroplasties. A practical application is expected in the correction of severe hypospadias or extensive urethral strictures.

Animals↗
PubMed1992

[Pyeloureteral lieberkuhn adenocarcinoma after trans-intestinal ureterostomy for bladder exstrophy].

The authors report a case of pyeloureteric adenocarcinoma in a urinary diversion inserted for bladder exstrophy and in a context of chronic pyelonephritis secondary to renal stones. The various aetiopathogenic hypotheses are discussed. Renal stones and chronic inflammation very probably played an important role in the development of this type of adenocarcinoma in the urothelium.

Adenocarcinoma↗
PubMed1991

[Peri-ureteral granuloma after teflon injection for vesico-ureteral reflux].

Based on two cases of correction of vesicoureteric reflux by endoscopic Teflon injection associated with a marked foreign body reaction, the authors analyse the tolerance of this substance for this type of treatment. On reviewing 29 cases of reflux, they found 3 failures (10%) of the method with 2 foreign body granulomas (7%). These complications, related to the use of Teflon, have been rarely reported in the literature, which essentially refers to the risks of migration of Teflon.

Administration, Intravesical↗
PubMed1987

[Intestinal stenosis, sequelae of necrotizing enterocolitis. Analysis of 9 cases].

Intestinal necrosis was a complication of necrotizing enterocolitis of the newborn in 9 of 42 cases. In 6 neonates it followed medical treatment of the enterocolitis, presenting in this case as an occlusive syndrome. After surgical treatment (3 cases) the diagnosis was made from radiologic imaging prior to reestablishment of digestive continuity. Surgery was necessary in all cases, and procedures used are described (technic, date of operation). The prognosis of enterocolitis is worsened by this stenosis (1 death in the 9 cases).

Enterocolitis, Pseudomembranous↗
PubMedDate not supplied

[Urethroplasty of the free colonic mucosa in rats. Preliminary study of the use of appendicular mucosa].

The various tissues used as free grafts in urethroplasties are associated with a high incidence of fistulae and strictures. The search for a new, more effective substitute had led the authors to study the possibility of using a new type of mucosa: appendicular mucosa. The size and cylindrical structure of the appendix and its easy resection make it an original and adapted urethral substitute. As most animals do not possess an appendix, an animal model of urethroplasty with colic mucosa has been used. A segmental distal urethrectomy has been performed on 40 rats, 14 had a simple urethral stent without any urethroplasty (Group I), for 7 wi performed the urethroplasty with a collagen tube (Group II) and for 19 an urethroplasty with free colic mucosa was performed (Group III), 3 to 6 weeks later, a macroscopic and microscopic study were realised. In group I and II the urethral duct developed a fibrosis and all rats had a severe stenosis when the stent went out. In those two groups, a urinary fistula has been developed in all rats except one. In group III, a neo-urethra was found. Under light microscopic examination a typical urothelium was observed in the mid and distal section and a keratinized squamous epithelium on the distal section. The results of the preliminary study let us believe that the digestive mucosa may be used for urethroplasty. Before we can propose the appendix mucosa in human surgery, it will be useful to perform sooner histological examination, then the genesis of the neo-urothelium should be understood.

Animals↗