Paulo Guilhardi
Assistant Professor of Psychology (Research):
Psychology
Phone: +1 401 863 6271
Paulo_Guilhardi@Brown.EDU
My research interests focus on basic learning processes, such as timing, choice, and appetitive and aversive conditioning, and on the application of these processes to human problems, such as masochism, and attention deficit hyperactivity disorder (ADHD).
Biography
Paulo Guilhardi is an experimental psychologist with research interests on basic learning processes, such as timing, choice, and appetitive and aversive conditioning, and on the application of these processes to human problems, such as attention deficit hyperactivity disorder (ADHD). His research is focused on developing and evaluating animal models of ADHD. A timing procedure provided independent measures of response rate, response pattern, and discrimination accuracy that were directly related to hyperactivity, impulsivity, and attention deficit symptoms described in ADHD. Dr. Guilhardi is currently investigating these symptoms and the effects of different independent variables on them using the Spontaneously Hypertensive Rats (SHR), a strain used as a genetic model of ADHD. Dr.Guilhardi received his B.S. and Clinical Psychology degree from Universidade Federal de São Carlos, Brazil, and earned a Ph.D. in Psychology at Brown University. He is currently an Assistant Professor (Research) in the Department of Psychology at Brown University.
Interests
My research interests focus on basic learning processes, such as timing, choice, and appetitive and aversive conditioning, and on the application of these processes to human problems, such as masochism, and attention deficit hyperactivity disorder (ADHD).
While obtaining my clinical psychology license in Brazil, I felt the increased necessity to relate basic research to clinical problems. The clinical work provided me with interesting problems but few solutions. It was difficult to study these problems under the clinical settings, with limited control of relevant variables. My decision was to simplify; I decided to investigate behavior in well-controlled environments with organisms with a known history. Since then, the focus of my research career has been to understand basic learning processes with rats and pigeons. My basic research includes topics such as the dynamics of acquisition and extinction of conditioned behavior, temporally controlled behavior, and the relationship between timing, conditioning, and choice. I have also used different theoretical models of behavior such as the Rescorla & Wagner Model, Scalar Timing Theory, Learning to Time, and Packet Theory to explain these data. This research provided me the skills to work successfully with large amounts of data, in order to describe the behavior of individuals and groups of subjects, quantitatively fit theories to the data, and evaluate fits of different theories to the data using different criteria, such as a Turing test (Church & Guilhardi, 2005).
The findings from my own research, as well as from others, have provided me with innovative procedures, stable behavioral measures, and theoretical explanations that can be used to study clinical problems in simple environments through the use of animal models. The general approach has made it possible for me to integrate topics, such as conditioning, timing, and choice, that were often investigated with different methods and theories. The focus of my current research has been to integrate those topics even further using an animal model of attention deficit disorder (ADHD). This direction of research will provide the identification of determining variables related to the etiology, symptom, and treatment. This identification promises to provide an outstanding tool that can be used with children.
My early career training
As an undergraduate I was awarded a research fellowship to investigate aversive control in rats; more specifically, to investigate mechanisms under which rats maintain high rates of responding even though responding was frequently and severely punished with electric shock. This research led to the conclusions that behavior that is frequently and severely punished is only maintained if the frequency and intensity of punishment is gradually introduced, and if the behavior is also reinforced. The underlying basic principles provided by this research had close relationship to human problems, such as masochism. In 1997, I was the recipient of a "Young Investigator Award" for my work in this area.
This research provided me the opportunity to understand basic processes and relate them to applied human problems. The nature of the explanation, however, was based on qualitative descriptions of the relationships between the independent and dependent variables. In 1998, as a junior in college, I had the opportunity to conduct research with Dr. Armando Machado at Indiana University. Dr. Machado introduced me to the study of timing behavior and quantitative explanatory models of behavior. This research tested predictions of two influential theories of timing, Scalar Timing Theory (SET) and Learning to Time (LeT), and was published in the Journal of the Experimental Analysis of Behavior (Machado & Guilhardi, 2000).
Basic research: acquiring skills, developing methods, and fitting theories to data.
A fascination for basic and applied research, the quantification of behavior, and the timing behavior led me to pursue the Ph.D. under mentorship of Dr. Russell M. Church in the Timing Lab at Brown University. During these years at Brown University, I have investigated how the temporal relationship between environmental cues (e.g. occurrence of stimuli such as noise) and reinforcements (e.g. food delivery) can be used to predict the learning of the pattern and rate of behavior of rats. A quantitative theory of timing and conditioning, Packet Theory, has been extended to account for the behavior trained under many procedures.
In a paper published in Learning & Behavior (Guilhardi & Church, 2005), Packet Theory was extended to predict the dynamics of temporal discrimination. The theory predicted different patterns of results produced by different dependent measures of acquisition. The fits to these dependent measures with different patterns were based on a single set of parameters. These, and other, dependent measures of fixed-interval performance, as well as analysis tools, were published in Behavior Research Methods, Instruments, and Computers (Guilhardi & Church, 2004). This publication also provided a case study of the data archiving and secondary data analysis.
Packet Theory was also extended to account for pattern and rate of responses under fixed and random interval schedules, and under schedules in which multiple time-markers are present and used as cues to the delivery of reinforcement. In addition, the theory was used to predict the tendency of behavior to occur in bouts of responses. This extension of the model was presented at the Society for Quantitative Analysis of Behavior (SQAB) and published in a special issue on the "quantitative analysis of behavior" in Behavioural Processes (Guilhardi, Keen, MacInnis, & Church, 2005).
In addition to acquisition, a series of papers addressed the response rate and pattern of temporal discrimination behavior after extensive extinction. Results showed that the memory for interval duration was preserved after extensive extinction when the conditions of acquisition and extinction were similar, learning of new intervals and context occurred during extinction when the conditions of acquisition and extinction differed (Guilhardi & Church, 2006). The dynamics of acquisition and extinction of temporal discrimination were also studied. The speed of acquisition was faster than the speed of acquisition. The Rescorla & Wagner model with the addition of a linear response-mapping rule was sufficient to account for the acquisition and extinction of response rate(Guilhardi, Yi, & Church, 2006). Another manuscript extended packet theory to account for the dynamics of extinction in addition to the dynamics of acquisition. An explicit solution of the theory has also been described (Guilhardi, Yi, & Church, submitted).
Current and future directions: integrating basic and applied research
I have reviewed the literature on animal models of ADHD and was dissatisfied with the current analogy of the hyperactivity, impulsivity, and attention deficit. Moreover, I was dissatisfied with a lack of studies exploring etiological and treatment aspects. At the same time, I found that my research (Guilhardi, 2005) had provided me with a behavioral procedure, behavioral measures, and theoretical explanations that could be directly used to develop and evaluate current animal models of ADHD. The procedure designed to relate timing, conditioning, and choice, provided independent measures of response rate, response pattern, and discrimination accuracy. These measures were directly related to the three symptoms described in ADHD: response rate was related to hyperactivity, response pattern to impulsivity, and discriminative accuracy to attention deficit. The development of this task along with a quantitative theory to explain the results, provide tools to study ADHD. As an Assistant Professor Research at Brown University, I am currently testing hyperactivity, impulsivity, and attention deficit in the Spontaneously Hypertensive Rats (SHR), a strain often used as a genetic model of ADHD.
In the future, I plan to try to isolate these measures and investigate effects of different independent variables on them. The study of the conditions under which the symptoms are exacerbated or eliminated in a simple laboratory environment will provide information about the processes underlying the etiology, symptomatology, and treatment of ADHD. Further development of the SHR model will provide a better understanding of the etiology, symptomatology, and treatment of ADHD.
In addition to conducting research on ADHD with rats, I intend to collect data using similar procedures with children diagnosed with ADHD and controls. In fact, this research is currently being implemented at Brown University. In addition, details for future research collaboration with children are concurrently being discussed with two major universities (Universidade Federal de São Carlos and Universidade de Campinas), and a clinical institute (Instituto de Análise do Comportamento de Campinas) in Brazil.
Another direction of research has recently been established through collaborations with Dr. Mark Laubach at Yale University and Rebecca Burwell at Brown University. This research will provide pre-frontal cortex single unit recordings from rats while performing a task similar to the one I am currently using to evaluate and develop the SHR model of ADHD. Collaborations with researchers who have experience with clinical populations as well as collaborations with researchers investigating the neurobiological bases of behavior, combined with my research skills using behavioral procedures, provides an integrative approach that will certainly produce outstanding outcomes. Such integrative approach is ambitious but realistic.
Degrees
Ph.D., Brown University, 2005
Awards
2005 - The Phi Beta Kappa Society
1996 to 1998 - Research Fellowship. Institutional Program of Scientific Initiating Fellowship(PIBIC/CNPq). Fellowship for researching at Universidade Federal de São Carlos.
1997 - Prêmio Jovem Pesquisador. The paper: Explorations on an animal model of masochism: Introductory effect of the aversive stimuli on a positively reinforced baseline, presented in the V Congresso de Iniciação Científica da Universidade Federal de São Carlos was awarded best session.
Affiliations
Eastern Psychological Association (EPA)
Society for the Quantitative Analysis of Behavior (SQAB)
Society for Comparative Cognition (CO3)
Associação Brasileira de Psicoterapia e Medicina Comportamental (ABPMC)
Association for Behavior Analysis (ABA)
Funded Research
N/A
