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PubMed1990

Limitations on the parallel guidance of visual search: color x color and orientation x orientation conjunctions.

In visual search for a conjunction it is much more difficult to search for the conjunction of 2 colors or 2 orientations than for Color x Orientation or Color x Shape conjunctions. The result is not limited to particular colors or shapes. Two colors cannot occupy the same spatial location in Color x Color searches. However, Experiments 6 and 7 show that Color x Shape searches remain efficient even if the color and shape are spatially separated. Our guided search model suggests that in searches for Color x Shape, a parallel color module can guide attention toward the correct color, whereas the shape module guides attention toward the correct shape. Together these 2 sources of guidance lead attention to the target. However, if a target is red and green among red-blue and green-blue distractors, it is not possible to guide search independently toward red items and green items or away from all blue items.

Adult↗
PubMed1993

Asymmetries in visual search for conjunctive targets.

Asymmetry is demonstrated between conjunctive targets in visual search with no detectable asymmetries between the individual features that compose these targets. Experiment 1 demonstrated this phenomenon for targets composed of color and shape. Experiment 2 and 4 demonstrate this asymmetry for targets composed of size and orientation and for targets composed of contrast level and orientation, respectively. Experiment 3 demonstrates that search rate of individual features cannot predict search rate for conjunctive targets. These results demonstrate the need for 2 levels of representations: one of features and one of conjunction of features. A model related to the modified feature integration theory is proposed to account for these results. The proposed model and other models of visual search are discussed.

Adult↗
PubMed1994

Search via recursive rejection (SERR): visual search for single and dual form-conjunction targets.

Models of visual search that assume spatially serial processing of conjunction stimuli break down when displays contain 2 identical conjunction targets: (a) They fail to account for the slopes of the target-absent reaction time (RT)/display size functions, both when the target-present response requires the detection of only 1 of the 2 targets and when it requires the detection of both targets and (b) under redundant target conditions, the probability of "fast" present RTs is greater than that expected from the independent (serial) processing of the target stimuli. This article shows that G. W. Humphreys and H.J. Müller's (1993) parallel search via recursive rejection (SERR) model can account for human search performance under dual-target conditions. In SERR, simple form conjunctions are coded and grouped (on the basis of their similarity) in a spatially parallel manner, and targets are detected through the activation of a temporary "template" or through the recursive rejection of grouped distractors.

Adult↗
PubMed2002

Roles of salience and strategy in conjunction search.

In some cases, the search for a conjunction target proceeds through the smaller group of elements in a display, whereas in others, search is limited to those elements that share a particular feature with the target. In 6 experiments, participants searched for a conjunction target among displays consisting of various proportions of 2 distractor types. Smaller-group search was more prevalent than target-feature search with denser displays and with features that were highly discriminable. Explicit instructions to limit search to a specific feature affected performance only when the discriminability of the guiding feature was much greater than the other target feature. Together, these experiments show that bottom-up factors have more influence in guiding conjunction searches than previously thought.

Analysis of Variance↗
PubMed2001

Conjunctive representations in learning and memory: principles of cortical and hippocampal function.

The authors present a theoretical framework for understanding the roles of the hippocampus and neocortex in learning and memory. This framework incorporates a theme found in many theories of hippocampal function: that the hippocampus is responsible for developing conjunctive representations binding together stimulus elements into a unitary representation that can later be recalled from partial input cues. This idea is contradicted by the fact that hippocampally lesioned rats can learn nonlinear discrimination problems that require conjunctive representations. The authors' framework accommodates this finding by establishing a principled division of labor, where the cortex is responsible for slow learning that integrates over multiple experiences to extract generalities whereas the hippocampus performs rapid learning of the arbitrary contents of individual experiences. This framework suggests that tasks involving rapid, incidental conjunctive learning are better tests of hippocampal function. The authors implement this framework in a computational neural network model and show that it can account for a wide range of data in animal learning.

Animals↗
PubMed1992

Proficient performance of a conjunctive, recursive task by an African gray parrot (Psittacus erithacus).

The comprehension skills of an African gray parrot (Psittacus erithacus), Alex, were tested on a taks that included a conjunctive condition. For each trial, Alex was shown different collections of 7 items, each collection chosen from among 100 objects of various combinations of shapes, colors, and materials, and he was asked to provide (vocally) information about the specific instance of one category of an item that was uniquely defined by the conjunction of two other categories (e.g., "What color is the [object defined by shape and material]?"). Other objects exemplified one, but not both, of these defining categories. Alex responded with an accuracy of 76.5%, which indicated that he understood all the elements in the question, including the conjunctive condition, and that he used these elements to guide his search for the one object in the collection that provided the requested information.

Animal Communication↗
PubMed2006

Speech perception for adults who use hearing aids in conjunction with cochlear implants in opposite ears.

This study aimed to (a) investigate the effect of using a hearing aid in conjunction with a cochlear implant in opposite ears on speech perception in quiet and in noise, (b) identify the speech information obtained from a hearing aid that is additive to the information obtained from a cochlear implant, and (c) explore the relationship between aided thresholds in the nonimplanted ear and speech perception benefit from wearing a hearing aid in conjunction with a cochlear implant in opposite ears. Fourteen adults who used the Nucleus 24 cochlear implant system in 1 ear participated in the study. All participants had either used a hearing aid in the nonimplanted ear for at least 75% of waking hours after cochlear implantation, and/or, hearing loss less than 90 dB HL in the low frequencies in the nonimplanted ear. Speech perception was evaluated in 3 conditions: cochlear implant alone (CI), hearing aid alone (HA), and cochlear implant in conjunction with hearing aid in opposite ears (CIHA). Three speech perception tests were used: consonant-vowel nucleus-consonant (CNC) words in quiet, City University of New York style (CUNY) sentences in coincident signal and noise, and spondees in coincidental and spatially separated signal and noise. Information transmission analyses were performed on the CNC responses. Of the 14 participants tested, 6 showed significant bimodal benefit on open-set speech perception measures and 5 showed benefit on close-set spondees. However, 2 participants showed poorer speech perception with CIHA than CI in at least 1 of the speech perception tests. Results of information transmission analyses showed that bimodal benefit (performance with CIHA minus that with CI) in quiet arises from improved perception of the low frequency components in speech. Results showed that participants with poorer aided thresholds in the mid-to-high frequencies demonstrated greater bimodal benefit. It is possible that the mid-to-high frequency information provided by the hearing aids may be conflicting with the cochlear implants.

Adult↗
PubMed1987

Episode organization and cohesive conjunctives in narratives of children with and without language disorder.

Language-disordered children (chronological ages [CA] 7:6 [years:months] to 10:6) were compared with children who have normal language skills in their ability to cohere episode units in verbally produced narratives following a movie viewing. Cohesion across the episode boundaries was measured by judging the accuracy of conjunctives used to conjoin sentences. Each story was presented twice, once to an adult who had shared the movie viewing with the child, and once to an adult who had not seen the movie. Results indicated that age correlated with the frequency of complete episodes in both groups of children, only the children with normal language skills changed the number of complete episodes as a function of the listener's shared information, neither group altered the accuracy of conjunctive use as a function of the listener, and both groups used a higher frequency of accurate conjunctives to conjoin sentences within an episode than to conjoin sentences across episodes. Results are discussed in terms of the effects of age, language disorder, and listener context on the varying levels of narrative organization.

Age Factors↗
PubMed2000

Involvement of the human frontal eye field and multiple parietal areas in covert visual selection during conjunction search.

Searching for a target object in a cluttered visual scene requires active visual attention if the target differs from distractors not by elementary visual features but rather by a feature conjunction. We used functional magnetic resonance imaging (fMRI) in human subjects to investigate the functional neuroanatomy of attentional mechanisms employed during conjunction search. In the experimental condition, subjects searched for a target defined by a conjunction of colour and orientation. In the baseline condition, subjects searched for a uniquely coloured target, regardless of its orientation. Eye movement recordings outside the scanner verified subjects' ability to maintain fixation during search. Reaction times indicated that the experimental condition was attentionally more demanding than the baseline condition. Differential activations between conditions were therefore ascribed to top-down modulation of neural activity. The frontal eye field, the ventral precentral sulcus and the following posterior parietal regions were consistently activated: (i) the postcentral sulcus; (ii) the posterior; and (iii) the anterior part of the intraparietal sulcus; and (iv) the junction of the intraparietal with the transverse occipital sulcus. Parietal regions were spatially distinct and displayed differential amplitudes of signal increase with a maximal amplitude in the posterior intraparietal sulcus. Less consistent activation was found in the lateral fusiform gyrus. These results suggest an involvement of the human frontal eye field in covert visual selection of potential targets during search. These results also provide evidence for a subdivision of posterior parietal cortex in multiple areas participating in covert visual selection, with a major contribution of the posterior intraparietal sulcus.

Adult↗
PubMed2001

Lipogranulomatous conjunctivitis: clinical findings from 21 eyes in 13 cats.

OBJECTIVE: The clinical and, where available, histologic features of lesions fitting a previous description of lipogranulomatous conjunctivitis were reviewed retrospectively from a series of cats. ANIMALS STUDIES: Thirteen cats (21 eyes) with lesions consistent with a diagnosis of lipogranulomatous conjunctivitis were seen over a 4-year period in a referral practice in southern Australia. Affected cats ranged in age from 6 to 16 years (mean 11.2 +/- 3.6 years). RESULTS: Twelve cats were domestic shorthair or longhair cats and one was a British shorthair cat. Five cats were white, four were bicolor, two were orange tabby and two were dilute orange tabby. Lesions were always found in the palpebral conjunctiva, adjacent to the eyelid margin. They affected upper eyelids only in five cases, and upper plus lower eyelids in eight cases. Lesions were bilateral in eight cases. Lesions were excised in eight cases, with resolution of associated irritation and no signs of lesion recurrence during a 4- to 21-month follow-up period. SUMMARY: Histologic features of tissues excised from surgically treated cases were consistent with a previous report of lipogranulomatous conjunctivitis and with descriptions of chalazia. A possible role of actinic radiation in the etiopathogenesis of lesions is discussed.

Animals↗
PubMed1989

Efficacy of neonatal ocular prophylaxis for the prevention of chlamydial and gonococcal conjunctivitis.

Opinions differ concerning the efficacy of prophylaxis against neonatal chlamydial and gonococcal conjunctivitis. From January 1986 through June 1988, we gave all infants born at Kings County Hospital Medical Center one of three prophylactic agents -- silver nitrate drops, erythromycin ophthalmic ointment, or tetracycline ophthalmic ointment. The treatments were rotated monthly. Gonococcal ophthalmia occurred in 8 of the 12,431 infants born during the study (0.06 percent), 1 in the silver nitrate group, 4 in the erythromycin group, and 3 in the tetracycline group (P not significant). Seven of these infants were born to women who had received no prenatal care. From September 1985 through December 1987, we screened 4357 pregnant women for cervical chlamydial infection, of whom 341 (8 percent) had positive cultures. Of their offspring, 230 were evaluated for neonatal chlamydial conjunctivitis; the incidence was 20 percent in the silver nitrate group, 14 percent in the erythromycin group, and 11 percent in the tetracycline group (P not significant). We conclude that neonatal ocular prophylaxis with either erythromycin or tetracycline ophthalmic ointment does not significantly reduce the incidence of chlamydial conjunctivitis in the offspring of mothers with chlamydial infection as compared with silver nitrate, and that better management of maternal chlamydial infection is therefore required. We also conclude that there is a small but appreciable incidence of neonatal gonococcal ophthalmia that could be prevented by better prenatal screening and treatment of maternal gonococcal infection.

Chlamydia Infections↗
PubMed1992

Distractor ratio and grouping processes in visual conjunction search.

According to feature integration theory, conjunction search is conducted via a serial self-terminating search. However, effects attributed to search processes operating on the entire display may actually reflect search restricted to elements defined by a single feature. In experiment 1 this question is addressed in a reaction-time (RT) paradigm by varying distractor ratios within an array of fixed size. For trials in which the target was present in the array, RT functions were roughly symmetric, the shortest RTs being for extreme distractor ratios, and the longest RTs being for arrays in which there were an equal number of each distractor type. This result is superficially consistent with Zohary and Hochstein's interpretation that subjects search for only one distractor type and are able to switch search strategy from trial to trial. However, negative-trial data from experiment 1 case doubt on this interpretation. In experiment 2 the possible role of 'pop out' and of distractor grouping in visual conjunction search is investigated. Results of experiment 2 suggest that grouping may play a more important role than does distractor ratio, and point to the importance of the spatial layout of the target and of the distractor elements in visual conjunction search. Results of experiment 2 also provide clear evidence that groups of spatially adjacent homogeneous elements may be processed as a unit.

Attention↗
PubMed2001

Spatially parallel processing of within-dimension conjunctions.

Within-dimension conjunction search for red-green targets amongst red-blue, and blue-green, nontargets is extremely inefficient (Wolfe et al, 1990 Journal of Experimental Psychology: Human Perception and Performance 16 879-892). We tested whether pairs of red-green conjunction targets can nevertheless be processed spatially in parallel. Participants made speeded detection responses whenever a red-green target was present. Across trials where a second identical target was present, the distribution of detection times was compatible with the assumption that targets were processed in parallel (Miller, 1982 Cognitive Psychology 14 247-279). We show that this was not an artifact of response-competition or feature-based processing. We suggest that within-dimension conjunctions can be processed spatially in parallel. Visual search for such items may be inefficient owing to within-dimension grouping between items.

Adult↗
PubMed1995

The effect of self-serving attribution on attraction in additive- and conjunctive-task groups.

The prediction that the effect of self-serving attribution on personal attraction will vary according to task type was tested. Twenty-four groups of Turkish students, each consisting of 1 participant and 3 confederates, received success feedback after having performed either an additive or a conjunctive task. Two of the confederates made either self-serving or group-serving attributions, whereas the 3rd confederate attributed success to the collective efforts of all group members. Following these attributions, the participants filled out a form to indicate the degree to which they preferred each member as a friend and a work mate. Self-serving attributors in the conjunctive-task condition were less preferred as friends than the self-serving attributors in the additive-task condition. Also, the additive-task participants' ratings for other group members were systematically higher than those of the conjunctive-task participants. Thus, there was a main effect of task type for both friends and workmates.

Adult↗
PubMed1993

Prospective randomized trial of high-dose interleukin-2 alone or in conjunction with lymphokine-activated killer cells for the treatment of patients with advanced cancer.

BACKGROUND: Treatment using interleukin-2 (IL-2) alone or in conjunction with lymphokine-activated killer (LAK) cells has been shown to mediate disease regression in selected patients with advanced cancer. PURPOSE: This prospective randomized trial was designed to determine whether the administration of LAK cells in conjunction with high-dose IL-2 alters response and survival rates, compared with those for IL-2 alone, in patients with advanced cancer. METHODS: The 181 patients who had metastatic cancer that had failed to respond to standard therapy or who had disease for which no effective therapy existed received treatment with high-dose IL-2 alone or with LAK cells plus IL-2. Both treatment groups were to receive the same dose of IL-2 administered according to the same schedule. IL-2 doses were omitted depending on the tolerance of the patient. Of the 181 patients, 97 had renal cell cancer and 54 had melanoma. RESULTS: Median potential follow-up was 63.2 months. There were 10 complete responses among the 85 assessable patients who received IL-2 plus LAK cells, compared with four among the 79 who received IL-2 alone. There were 14 and 12 partial responses, respectively. Complete response continues in seven patients at 50-66 months. The 36-month actuarial survival with IL-2 plus LAK cells was 31%, compared with 17% with IL-2 alone (two-sided P value [P2] = .089). A trend toward improved survival was seen for patients with melanoma who received IL-2 plus LAK cells, compared with those who received IL-2 alone (24-month survival: 32% versus 15%; 48-month survival: 18% versus 4%; P2 = .064 [corrected]). None of 26 patients with melanoma who received IL-2 alone are alive; five of 28 who received IL-2 plus LAK cells are alive, and three continue in complete response. No difference in survival was seen in patients with renal cell cancer in the two treatment groups. There were six treatment-related deaths (3.3%); three were due to myocardial infarction. Other toxic effects resolved by discontinuation of IL-2. Many toxic effects were related to increased vascular permeability induced by IL-2. CONCLUSIONS: Some patients with metastatic cancer have prolonged remission when they are treated with high-dose IL-2 alone or in conjunction with LAK cells. Our results suggest a trend toward increased survival when IL-2 is given with LAK cells in patients with melanoma, but no trend was observed for patients with renal cell cancer. IMPLICATIONS: As these studies continue, efforts are underway to develop improved immunotherapies using tumor-infiltrating lymphocytes (TIL) and gene-modified TIL.

Adolescent↗
PubMed1999

The popout in some conjunction searches is due to perceptual grouping.

The target in a visual search task usually pops out if it can be distinguished from its background on the basis of only one visual feature but not if the target represents a conjunction of two or more features. However, several recent reports suggest that in certain cases, search targets defined by a conjunction of two features also pop out. We have reinvestigated three pairs of such features to determine whether the popout in these cases can be attributed to perceptual grouping. We find that that in all three cases, popout no longer occurs when perceptual grouping is degraded, suggesting that the popout is the result of perceptual grouping and not of novel mechanism/s of conjunction search.

Depth Perception↗
PubMed2004

Beneficial effects of costimulatory blockade with anti-inducible costimulator antibody in conjunction with CTLA4Ig on prevention of islet xenograft rejection from rat to mouse.

BACKGROUND: Costimulatory signals have been reported to play an important role in islet-xenograft rejection, although the precise mechanisms remain unknown. The aim of the present study was to determine a role of a novel costimulatory molecule, inducible costimulator (ICOS), in rat islet-xenograft rejection in conjunction with CTLA4Ig with respect to cellular as well as humoral immune responses. METHODS: Isolated rat islets were transplanted into the liver of streptozotocin (180 mg/kg) induced diabetic mice. Cellular immune responses to islet xenografts, and productions of anti-rat antibody in mice were examined by flow cytometry (FACS) after transplantation. RESULTS: Intrahepatic rat islet xenografts were rejected in mice within 8 days after transplantation. FACS analysis revealed an expansion of CD8(+) T cells in the liver as well as a production of anti-rat antibody in recipient mice in association with rejection. The treatment with anti-ICOS antibody in conjunction with CTLA4Ig produced a marked prolongation of islet-xenograft survival with neither expansion of CD8(+) T cells nor production of anti-rat antibody, whereas, in contrast, those treated with anti-ICOS antibody or CTLA4Ig alone did not have prolonged survival, and CD8(+) T cells were expanded. CONCLUSION: These findings demonstrate that cellular rather than humoral immune responses are considered responsible for islet-xenograft rejection from rat to mouse and that the blockade of costimulatory signals with anti-ICOS antibody in conjunction with CTLA4Ig has a favorable effect on prevention of islet xenograft rejection.

Abatacept↗
PubMed1981

Adeno-viral kerato conjunctivitis.

In summer, 1976 an epidemic of Kerato Conjunctivitis commenced in Melbourne, Australia. A total of 422 patients was studied in the adeno-viral clinic at the Royal Victorian Eye and Ear Hospital, Melbourne, from 1976 to 1979. Most patients were referred from the Casualty Department of the hospital, but others came from private practice. A total of 72 cases were adeno-viral with positive cultures. Types 8 and 19 predominated, but sporadic cases of types 1, 3, 4 and 7 were also isolated. Herpes Simplex type 1 was positive in 13 patients. The hospital staff were involved in spread of adeno-virus type 8. Six patients contracted Kerato-Conjunctivitis following removal of corneal foreign bodies from the casualty ward, and several patients contracted epidemic Kerato-Conjunctivitis after beta-irradiation post-pterygium surgery. These latter two methods of infection have not been reported before. Treatment and prevention is discussed.

Adenoviridae Infections↗