1982 — 1986 |
Ratcliff, Roger |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Order Relations in Perceptual Matching |
0.97 |
1985 — 2009 |
Ratcliff, Roger |
K05Activity Code Description: For the support of a research scientist qualified to pursue independent research which would extend the research program of the sponsoring institution, or to direct an essential part of this research program. R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R37Activity Code Description: To provide long-term grant support to investigators whose research competence and productivity are distinctly superior and who are highly likely to continue to perform in an outstanding manner. Investigators may not apply for a MERIT award. Program staff and/or members of the cognizant National Advisory Council/Board will identify candidates for the MERIT award during the course of review of competing research grant applications prepared and submitted in accordance with regular PHS requirements. |
Retrieval Processes in Memory
The highest level goal of the proposed research is an understanding of the processes and structures of human memory and the processes involved in simple decision making. Investigation is planned in five theoretically related domains. In the first domain, three models of choice reaction time (the diffusion model, the OU model, and the accumulator model) will be tested against data from simple perceptual decision tasks and from higher level cognitive tasks. Second, the models' abilities to elucidate the processes by which information is retrieved from long term memory will be examined. The aim is to see whether the reaction time models can be usefully combined with the new memory models that have been developed recently, and if so, provide simultaneous empirical tests of both kinds of model. Third, relatively little work has been done on testing models for situations in which there are more than two response choices, in part because multichoice models of reaction time are often mathematically intractable and they have many parameters. But with fast computers and large experiments, we will be able to constrain and test the models. Fourth, our work with reaction time models has naturally led to tests of the currently leading models for categorization, exemplar models and distance from criterion models. We plan to examine ways to distinguish between these classes of models and also add to them mechanisms for predicting decision response times. Fifth, we continue work on implicit memory models. Research on implicit memory has usually progressed without any specific models of the processes involved in the tasks used to assess implicit memory. By proposing such models, we hope to raise the debate about implicit memory to consideration of the mechanisms by which priming effects come about. We plan to develop models for the frequently used picture naming and stern completion tasks. Overall, the proposed research represents the interaction of two methodologies: the development of explicit models of processing and representation and the development of empirical tests and data bases for those models. An important theme is the use of new models to serve as competitors for well established views, with the aim of driving research in new directions. The proposed research is relevant to themes described in the NIMH "Decade of the Brain" report to Congress. The broad class of models to be examined can be seen as neurally inspired, and these models have been applied to various pathologies (e.g., amnesia and dyslexia). Future applications of well-validated models could help discriminate such issues as whether memory deficits are due to encoding or retrieval problems or whether rapid automatic processes or slower more conscious ones are faulty. Reaction time models especially might lead to diagnostic techniques that are non-invasive and relatively inexpensive. In general, the more we know about the human cognitive system, the more we can improve and augment traditional diagnostic methods.
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1 |
1990 — 1993 |
Ratcliff, Roger |
K02Activity Code Description: Undocumented code - click on the grant title for more information. |
Retrieval Processes in Memory: Rsa @ Northwestern University
The proposed research is designed to examine models of human memory and processes of retrieval from memory, and to provide empirical data to test and expand the models. the first models evaluated are global memory models that assume a test item presented for recognition contacts all of memory to determine an overall value of match by which to discriminate old from new test items. The second class of models is connectionist (neural-like) models and these assume that an item is distributed as a set of features and that there are multiple layers of features (e.g., input and output layers). The proposal describes hypothetical processes of recognition within a connectionist framework and demonstrates problems with the models in accounting for forgetting and learning. Alternative connectionist/neural schemes are proposed as ways of overcoming the problems. Other sections deal with empirical tests for both global memory models and the connectionist models, the time course of availability of different kinds of information, tests of a new view of priming phenomena, and extensions of reaction time models from two-choice to multiple-choice decisions. The proposed work is relevant to mental health because of its investigation of the neurally-inspired connectionist models which offer a new framework with which to view various sorts of brain damage such as amnesia resulting from Alzheimer's disease or Korsakoff's syndrome. Other proposed work will advance our understanding of reaction time models and measures, and therefore advance the future possible application of these techniques and measures to understanding brain deficits and diagnosing those deficits.
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0.942 |
1991 |
Ratcliff, Roger |
S15Activity Code Description: Undocumented code - click on the grant title for more information. |
Small Instrumentation Grant @ Northwestern University
biomedical equipment purchase;
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0.942 |
1994 |
Ratcliff, Roger |
K02Activity Code Description: Undocumented code - click on the grant title for more information. |
Retrieval Processes in Memory--Rsa @ Northwestern University
The proposed research is designed to examine models of human memory and processes of retrieval from memory, and to provide empirical data to test and expand the models. the first models evaluated are global memory models that assume a test item presented for recognition contacts all of memory to determine an overall value of match by which to discriminate old from new test items. The second class of models is connectionist (neural-like) models and these assume that an item is distributed as a set of features and that there are multiple layers of features (e.g., input and output layers). The proposal describes hypothetical processes of recognition within a connectionist framework and demonstrates problems with the models in accounting for forgetting and learning. Alternative connectionist/neural schemes are proposed as ways of overcoming the problems. Other sections deal with empirical tests for both global memory models and the connectionist models, the time course of availability of different kinds of information, tests of a new view of priming phenomena, and extensions of reaction time models from two-choice to multiple-choice decisions. The proposed work is relevant to mental health because of its investigation of the neurally-inspired connectionist models which offer a new framework with which to view various sorts of brain damage such as amnesia resulting from Alzheimer's disease or Korsakoff's syndrome. Other proposed work will advance our understanding of reaction time models and measures, and therefore advance the future possible application of these techniques and measures to understanding brain deficits and diagnosing those deficits.
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0.942 |
1999 — 2003 |
Ratcliff, Roger |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Modeling the Effects of Aging On Reaction Time @ Northwestern University
DESCRIPTION (adapted from investigator's abstract): The investigator proposes to bring theoretical modeling from the reaction time domain to bear on the domain of aging and reaction time. Random walk and diffusion models are able to fit a range of experimental data beyond mean reaction time, and there appears to be a consensus that these models are setting new standards in accounting for reaction time phenomena. Five lines of experiments are proposed, each requiring two-choice decisions about simple cognitive and perceptual stimuli. Each kind of experiment places different limits on cognitive processes: the first two require subjects to learn stimulus-to-response mappings; the second two limit perceptual processes by limiting encoding time and stimulus discriminability; and the third requires memory. For all five tasks, performance will be examined with standard reaction time tasks, speed versus accuracy instructions, and deadlines that limit the time subjects have to respond. Models will be fit to all of the data from each task, including reaction times for correct and error responses, response accuracy, the relations among reaction time and accuracy, and the shapes of the reaction time distributions. Parameters of the models will be used to interpret aging deficits. For example, the parameters of the diffusion model allow the quality of the information entering decision processes to be separated from other components of the processes. The investigators anticipate that this theoretical approach will provide a more complete picture of processing than the Brinley plot analyses that currently dominate explanations of aging effects on reaction time.
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1 |
1999 — 2003 |
Ratcliff, Roger |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Neural Recordings and Reaction Time Models @ Northwestern University
The proposed research has two aims: The first is to use neuronal recordings in awake behaving rhesus monkeys to test models of rapid two-choice decision making that have been derived from data from human subjects. The models have been applied to simple perceptual tasks in which humans are asked to decide which of two stimuli was displayed, and they provide a good description of the speed and accuracy characteristics of the data. Monkeys can be trained to perform the same perceptual tasks with relative ease, using eye movements to one of two targets to indicate their decisions instead of the key presses used by humans. Our aim is to investigate whether the components of processing identified by cognitive models are reflected in neural activities. The second aim of the research is to investigate the joint behavior of small subsets of the neuronal populations that decide the direction, distance, and timing of eye movements. We plan to use simultaneous recordings from up to six neurons to examine correlations in the activities of neurons of different types and locations. Central questions are whether neurons hypothesized to perform the same function exhibit the same patterns of firing, whether neurons in the different parts of the oculomotor system show synchronous activities, whether the neurons responsible for movement to one of the possible choices interact with the neurons responsible for movement to the other choice, and how changes in stimulus information in the course of a single trial affect neuronal firing rates. The two aims of the research are tightly intertwined in that hypotheses and results from one of the domains will inform choices of hypotheses in the other. The primary oculomotor system is ideal for examining the neural decision processes that precede the generation of eye movements. We propose to investigate the possibility that neurons in the frontal eye field and superior colliculus that show preparatory and saccade-related burst activities prior to eye movements map onto the components of the diffusion model. To put it naively, wouldn't it be amazing if this neural activity was well-described by the characteristics of the accumulation of information reaching a threshold in the diffusion model? With this possibility in mind, the beginning phases of the proposed research will use the diffusion model to guide the designs of experiments with monkeys, to provide estimates of component processes through model fits to the behavioral data, and to guide the analysis of neural data. These experiments will make direct comparisons between human and monkey decision-making systems. Because of known and expected similarities between rhesus monkey and human oculomotor systems, these experiments will also provide a model for the functional organization of the neural control of voluntary movement in humans.
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0.942 |
2006 — 2010 |
Ratcliff, Roger |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Theoretical Analysis of the Effects of Aging On Memory and Reaction Time
DESCRIPTION (provided by applicant): In previously funded research (National Institute of Aging, 1999-2005), we used theories of two-choice decision making to explore the effects of aging on cognition. The theories were severely challenged by wide ranges of performance levels and the competing demands of large numbers of experimental conditions, but they were successful in jointly accounting for all the response time and accuracy data for young and older adults. The theories allowed separation of the components of processing involved in two-choice decisions and determination of which components were affected by aging. The quality of the information obtained from stimuli was usually not worse for 60-90 year old adults than college students, although the older adults were generally slower in non-decision components of processing and they adopted more conservative decision criteria. In the proposed research, the theories will be applied to four main issues, all central to the mission of NIA: First, we plan to investigate whether performance on simple two-choice tasks can be improved for older adults by training on laboratory tasks and/or computer-based training packages, which components of processing identified by the theories can be improved with training, and under what conditions do improvements in processing transfer from one task to another? Second, we plan to investigate which components of processing are affected for patients with early Alzheimer's disease and patients with Mild Cognitive Impairment compared to normal healthy adults. If one or another of the components is differentially affected among the three populations, it might provide a signature to aid in diagnosis. Third, we plan to examine the effects of aging on a broad sample of healthy young and older adults. Most of our completed work has focused on adults with college educations. We may find that aging leads to larger decrements in performance and components of processing for adults with less education and/or lower cognitive abilities. Fourth, we plan to extend our theories and empirical investigations to tasks that require associative memory, a kind of memory that often shows large decrements with aging. In addition to these four main issues, we plan to check that conclusions about the effects of aging, impairment, practice, and task requirements are consistent across theories of two-choice decision making, and to check the conclusions from the standard two-choice response time paradigm against conclusions from the response signal paradigm.
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1 |
2012 — 2017 |
Ratcliff, Roger |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Toward Using Comprehensive Decision-Making Models in Neuropsychological Testing
DESCRIPTION (provided by applicant): In everyday life, fast one-, two-, and multi-choice decisions are common. Rapid decisions must be made based on any number of sources of information, often in the face of quickly changing conditions. The paramount aim of the proposed research is to move a set of Cognitive Psychology theories to practical issues. The plan is to use the theories to develop tools with which to measure the basic, elemental processes by which rapid decisions are made. Currently, modern cognitive theories have had little impact on neuropsychological testing. The goal of the proposed research is to begin to change this by providing a coherent, theory-based account of rapid one-, two-, and multi-choice decisions. The Cognitive Psychology models to be used are designed to explain the accuracy and speed of simple decisions in the research domains of perception and memory and to bridge to the practical domains of cognition and driving, and cognition and aging. For example, in driving, deciding to slow at the onset of another car's brake lights is a one-choice decision; deciding whether a patch of light is darker or brighter than the background is a two-choice decision; rating the confidence in whether a word or picture was studied earlier is a multi-choice decision. The three models we will use, one for one-choice decisions, one for two-choice decisions, and one for multi-choice decisions, use diffusion processes and share foundational properties. Each divides processing into similar components: the quality of the information upon which a decision is based, the criteria that determine how much information must be available in order to make a decision, the encoding and memory-access processes that make the needed information available, and the response execution processes that make a decision overt. Central to our aims, the models allow examination of the particular, moment-by-moment, processes that take place between the presentation of a stimulus and the response to it. The research will investigate these processes for college-age adults and elderly adults (ages 60-74). The planned approach is to develop and test new models for one- and multi-choice decisions in a variety of domains. The one-choice model will be tested in experiments that involve simulated driving and perceptual tasks that have been used to assess the effects of sleep deprivation on cognition. The multi-choice model will be tested in the domains of memory and perceptual judgments. In both cases, planned experiments will allow comparisons of the two models to a currently well-validated two-choice model. The eventual goal of the proposed research is the development of neuropsychological tests that can be used to assess the impacts on cognition of, for example, concussion, aging, and chemotherapy. The research will be innovative in that the one-, two- and multi-choice models have not previously been used in the diagnosis of cognitive impairments or in the tracking of recovery from them.
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1 |
2017 — 2021 |
Mckoon, Gail A Ratcliff, Roger |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R56Activity Code Description: To provide limited interim research support based on the merit of a pending R01 application while applicant gathers additional data to revise a new or competing renewal application. This grant will underwrite highly meritorious applications that if given the opportunity to revise their application could meet IC recommended standards and would be missed opportunities if not funded. Interim funded ends when the applicant succeeds in obtaining an R01 or other competing award built on the R56 grant. These awards are not renewable. |
Decision Making On Continuous Scales in Aging and Alzheimers Disease
Project Summary/Abstract The goal of the project is to develop a model that explains how decisions are made about information that is continuously distributed across space, with decisions made on continuous scales. The model will provide a unified explanation of the full range of decision-making data, including accuracy, the distributions of response times for correct and incorrect responses, how they change with manipulations of independent variables, and how they differ among individuals and groups of individuals. The totality of these data will place severe constraints on the development of the model and its success. The tasks used to test the model will ask participants to make simple decisions quickly; for example, point to the area on a circle that is the brightest. Brightness is a continuous scale and responses are made on a continuous scale (the circle). Large, comprehensive bodies of data will be collected for decision-making in perception, long-term memory, working memory, and numeracy. Statistical properties of the model will be examined and the numbers of observations needed will be determined for experiments with clinical patients, children, and other populations for whom the time for testing must be short. Four populations of adults will be studied: young adults, adults with Mild Cognitive Impairment (MCI), adults with early Alzheimer's Disease (AD), and older adults who have no cognitive impairments. The aim will be to understand how normal aging affects individual components of processing in continuous decision-making and how MCI and early AD affect the components. Almost no research has been conducted with AD and MCI patients that models the time course of decision-making and no research has been done for decisions made on continuous response scales about continuously distributed information. It is not known if the components of decision-making are the same for MCI and AD patients as for unimpaired older adults and it is not known how independent variables (e.g., the difficulty of a task) affect performance for MCI and AD patients. It is also not known whether a modeling approach can uncover preserved skills not discernible from accuracy and RT data alone.
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1 |
2017 — 2021 |
Mckoon, Gail A Ratcliff, Roger |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Integrated Cognitive and Decision Models With Applications to Aging and Numeracy
Project Summary/Abstract Our primary methodological/theoretical goal is to develop models that integrate models of how information is represented with models of how decisions are made. The domain of application will be numeracy: how numeracy is represented in the cognitive system and how it is used in making decisions. The specific goals for numeracy are to understand the basic processes involved in numeracy skills and to produce measures with which to understand the relationships between basic processes and higher-level skills. We will examine statistical properties of the integrated models and work with the authors of publicly available diffusion-model fitting packages to make the integrated models widely available. The decision model we will use is the well-established diffusion decision model, which provides a unified explanation of the full range of data for simple two-choice tasks of the kinds we will use, including the distributions of response times for correct and incorrect responses, how the distributions and accuracy change with manipulations of independent variables, and how they change with differences among individuals and groups of individuals. The representation models we will test assume distributed representations over numerosity and they will produce the measures of numeracy that drive decision processes. A successful representation model will be one for which the measures accurately predict, when translated through the diffusion model, response time and accuracy data. The proposed research will examine low-level skills, as measured by applying the models to simple numeracy discrimination and memory tasks. Relations will then be examined between these skills, working memory, and speed-of-processing and also between the skills and performance on standardized tests of higher-level math abilities, financial numeracy abilities, and health numeracy abilities. All of these tasks and measures will be tested with college-age adults, adults with Mild Cognitive Impairment, adults with early and moderate Alzheimer's disease, and cognitively unimpaired age-matched adults. Questions will include how numeracy abilities decline with normal aging and how they are impacted by cognitive impairment. It may be that impairments in numeracy abilities precede memory impairments and if so, lead to earlier treatments and earlier interventions in health and financial decision making. 1
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