I conduct research in a variety of areas that include areas that have been brought to my attention by students with whom I subsequently publish. Authors who are current or former students are listed in red. I have an enduring interest in behavioral assessment generally and activity measurement in particular using a technology called actigraphy. I have written a book on this subject.
Tryon, W. W. (1991). Activity measurement in psychology and medicine. New York: Plenum.
My other areas of interest include exploring new methods of psychological assessment that entail measuring response latency, neuropsychological assessment, statistics, and connectionism as described below.
Asperger's Syndrome
I am currently conducting a personality study of young adults with Asperger's Syndrome. Please visit my web page for this project.
Reliability and Validity of Actigraphs
Actigraphs are small lightweight typically waist and/or wrist worn computer-based devices that use an accelerometer to continuously (600 times per minute) measure movement at the site of attachment and store the average result in memory 1,440 times per 24 hour period for days and weeks as necessary. Unlike psychological tests whose measurement properties can only be determined by administering the test to people, the reliability and validity of actigraphs can be studied under laboratory conditions. The following two articles demonstrate that actigraphs are extraordinarily reliable and valid. Step counters (digital pedometers) are an inexpensive and less informative but still highly useful in quantifying activity level.
Tryon, W. W. (2005). The reliability and validity of two ambulatory monitoring actigraphs. Behavior Research Methods Instruments & Computers, 37, 492-497.
Tryon, W. W., & Williams, R. (1996). Fully proportional actigraphy: A new instrument. Behavior Research Methods Instruments & Computers, 28, 392-403.
Tryon, W. W., Pinto, L. P., & Morrison, D. F. (1991). Reliability assessment of pedometer activity measurements. Journal of Psychopathology and Behavioral Assessment, 13, 27-44.
Attention-Deficit Hyperactivity Disorder (ADHD)
The central clinical importance of motor excess as a core DSM-IV criterion of the Combined Type of ADHD was emphasized by the NIH consensus study. The Inhibitory Deficit Hypothesis is a leading theory of ADHD that is supported by considerable empirical evidence. It maintains that children with the combined form of ADHD suffer from a form of cortical release due to an impaired ability to inhibit thought and action. The resulting cortical release leads to pervasive hyperactivity, inattention, impulsivity, poor judgment and impaired social relationships that collectively place these children at risk for engaging in antisocial activities and drug use and developing conduct disorder. Studies provide substantial empirical evidence that childhood hyperactivity is a risk factor for subsequent psychosocial maladjustment in adolescence. Studies that have followed children with ADHD for 4 to 14 years have reported a major risk for subsequent aggressive, antisocial, and delinquent behaviors.
My research has focused on the question of whether children who are rated as hyperactive by teachers and parents are measurably hyperactive? This question is especially important because the answer carries implications for the validity of contemporary diagnostic practices concerning ADHD which depend heavily on teacher and parent reports. The two studies listed below reveal that children who are rated as hyperactive and frequently not measurably so.
Licht, C. A., & Tryon, W. W. (2006). Are Children Diagnosed with the Combined Form of ADHD Pervasively Hyperactive? Manuscript submitted for publication.
Tryon, W. W., & Pinto, L. P. (1994). Comparing activity measurements and ratings. Behavior Modification, 18, 251-261.
Pinto, L. P., & Tryon, W. W. (1996). Activity measurements support dimensional assessment. Behavior Modification, 20, 243-258.
I am currently using a feedback actigraph to provide a pharmacological alternative for treating hyperactivity. Preliminary findings have been very encouraging. Only a preprint is currently available as this article has yet to be published.
Tryon, W. W., Tryon, G. S., Kazlausky, T., Gruen, W., & Swanson, J. D. (2006). Reducing Hyperactivity with a Feedback Actigraph: Initial Findings. Journal of Clinical Child Psychology and Psychiatry,
11, 607-617.
I have a $10,000 grant from the MINT foundation to conduct a pilot MRI study investigating the extent to which three weeks of clinical treatment with the feedback actigraph activates the attention centers of the brain.
Sleep and Circadian Rhythm
Sleep is officially objectively measured using polysomnography (PSG) during three nights in a sleep laboratory. Home PSG is also available. Patients are frequently asked to keep sleep logs where they record the time they went to sleep, awakenings during the night, and the time they awoke. Wrist actigraphy provides an additional objective sleep measure (Tryon, 2004) that has been well validated against PSG (Tryon, 1996). My work with Coffield detected sleep problems upon admission in depressed patients, improvement at the point of discharge but notable residual sleep problems.
Tryon, W. W. (2004). Issues of validity in actigraphic sleep assessment. Sleep, 27, 158-165.
Tryon, W. W. (1996). Nocturnal activity and sleep assessment. Clinical Psychology Review, 16, 197-213.
Coffield, T. G., & Tryon, W. W. (2004). Construct validation of actigraphic sleep measures in hospitalized depressed patients. Behavioral Sleep Medicine, 2, 24-40.
Chronic Fatigue Syndrome (CFS) was initially defined as a 50% or more reduction in activity level from the premorbid state. Activity level reductions continue to play an important role in current definitions of chronic fatigue syndrome. CFS reduces daytime activity level somewhat but it devastates sleep and consequently upsets the normal circadian rhythm as demonstrated in the following study.
Tryon, W. W. Jason, L., Frankenberry, E., Torres-Harding, S. (2004). Chronic fatigue syndrome Impairs circadian rhythm of activity level. Physiology & Behavior, 82, 849-853.
Actigraphy has been used to study affective disorders. I was among the first to document that depression reduces activity in outpatients (Futterman & Tryon, 1994) and college students (Barkley & Tryon, 1995) in their natural environments.
Futterman, C. S., & Tryon, W. W. (1994). Psychomotor retardation found in depressed outpatient women. Journal of Behavior Therapy and Experimental Psychiatry, 25, 41-48.
Barkley, T. J., & Tryon, W. W. (1995). Psychomotor Retardation Found in College Students Seeking Counseling. Behaviour Research and Therapy, 33, 977-984.
Eating Disorders
Bodyweight extremes appear to alter activity level. At one end of the spectrum, obesity reduces activity level.
Tryon, W. W., Goldberg, J. L., & Morrison, D. F. (1992). Activity decreases as percent overweight increases. International Journal of Obesity, 16, 591-595.
Tryon, W. W. (1987). Activity as a function of body weight. The American Journal of Clinical Nutrition, 46, 451-455.
Persons diagnosed with anorexia nervosa are expected to be hyperactive. I have only had access to a hospitalized sample with this diagnosis by which time they had lost so much weight that they had become inactive. We found that activity increases were associated with weight gains and clinical progress.
Falk, J. R., Halmi, K. A., & Tryon, W. W. (1985). Activity measures in anorexia nervosa. Archives of General Psychiatry, 42, 811-814.
Activity Level as a Personality Factor
Activity level is the first stable individual difference (personality factor) to develop at around gestational week 34. Activity level is a prominent factor of infant temperament. All major theorists concerned with infant temperament agree that activity level constitutes a major dimension of infant temperament. Behavior genetic studies demonstrate that activity level is a highly heritable personality factor. A breeding study produced a strain of high active and a strain of low active mice over 30 generations resulting in two non-overlapping activity distributions.
Activity level remains a prominent factor of personality during middle childhood. Investigators of adult temperament and personality report evidence of an independent activity factor in adult personality. The Guilford-Zimmerman Temperament Survey, and the Dimensions of Temperament Scale - Revised contain activity level scales. The Five Factor Model (FFM) of personality maintains that activity level is a facet of Extraversion. The FFM is heavily based on factor analysis which is known to be sensitive to the variables analyzed. I have pilot data showing that when objective measures of activity level are factor analyzed along with FFM measures that a sixth activity level factor emerges. I am interested in working with students to further this line of inquiry.
Psychological Assessment via Response Latency
Computer administration of psychological tests enables one to measure the time take to answer each question. Response latency is a behavioral measure that is thought to provide additional information beyond the answer. For example, depressed people may take longer to answer questions than nondepressed people.
Casey, M., & Tryon, W. W. (2001). Validating a Double Press Method for Computer Administration of Personality Inventory Items. Psychological Assessment, 13, 521-530.
Tryon, W. W., & Mulloy, J. M. (1993). Further validation of computer-assessed response time to emotionally evocative stimuli. Journal of Personality Assessment, 61, 231-236.
All methods of measuring response times to answer written questions are flawed in one-way or another. In order to more accurately measure response times, I developed a computer administered visual-analog procedure. The participant is first familiarized with a labeled horizontal continuum of interest. The participant presents themselves with an “item” in the form of a vertical marker somewhere along the continuum. They are instructed to endorse or not by pressing a “yes” or “no” key. Positions along the entire continuum are sampled an odd number of times. Consecutive locations that are endorsed 100% of the time for a continuously true area. The middle of this area is taken as the person’s trait location. What the width of this area means is unclear at this point and require future research to determine.
Corby, B. J., & Tryon, W. W. (2006). Validating a New Method for Quantifying Traits: The Systematic Computer-Administered Visual Analog. Journal of Research in Personality, 40, 285-312.
Neuropsychological Testing
I have a cognitive neuropsychological science perspective and support student research in the area of neuropsychological testing.
Fertuck, E. A., Marsano-Jozefowicz, S., Stanley, B., Tryon, W. W., Oquendo, M., Mann, J. J., & Keilp. J. G. (2006). The impact of borderline personality disorder and anxiety on neuropsychological performance in major depression. Journal of Personality Disorder, 20, 55-70.
Baerwald, J. P., Tryon, W. W., & Sanford, J. (2005). Bimodal response sensitivity and bias in a test of sustained attention contrasting patients with schizophrenia and bipolar disorder to normal comparison group. Archives of Clinical Neuropsychology, 20, 17-32.
Gorlyn, M., Keilp, J. G., Tryon, W. W., & Mann, J. J. (2005). Performance test correlates of component factors of impulsivity. Personality and Individual Differences, 38, 1549-1559.
Baerwald, J. P., Tryon, W. W., & Sandford, J. (2001). Modal attention asymmetry in patients with schizophrenia and bipolar disorder. Neuropsychology, 15, 535-543.
Trudel, T. M., Tryon, W. W., & Purdum, C. M. (1999). Awareness of disability and long-term outcome after traumatic brain injury. Rehabilitation Psychology, 43, 267-281.
Medalia, A., Aluma, M., Tryon, W., & Merriam, A. E. (1998). The effectiveness of attention training in schizophrenia. Schizophrenia Bulletin, 24, 147-152.
Statistics
Null Hypothesis Statistical Testing has been problematic since its introduction by Sir Ronald Fisher in 1927 (Tryon, 1998). Even noted statistical authorities seem unable to consistently use these methods correctly despite more than half a century of well intended educational efforts. I took a human factors approach to the problem and introduced Inferential Confidence Intervals (ICIs) as an integrated method of determining statistical difference, equivalence, and indeterminacy (Tryon, 2001).
Tryon, W. W. (1998). The inscrutable null hypothesis. American Psychologist, 53, 796.
Tryon, W. W. (2001). Evaluating statistical difference, equivalence, and indeterminacy using inferential confidence intervals: An integrated alternative method of conducting null hypothesis statistical tests. Psychological Methods, 6, 371-386.
With assistance from Dr. Charles Lewis, the following article corrects the formula for the reduction factor E and further developes applications to statistical equivalence. Of special note is the introduction of Hybrid Confidence Intervals that combine both Descriptive and Inferential confidence intervals. They are intended to replace error bars because they reveal both the error associated with the mean and provide a visual basis for determining statistical difference, equivalence, indeterminacy, and trivial difference.
Tryon, W. W., & Lewis, C. (2008). An Inferential Confidence Interval Method of Establishing Statistical Equivalence That Corrects Tryon’s (2001) Reduction Factor. Psychological Methods, 13, 272-278.
With assistance from Dr. Charles Lewis, my ICI method has been extended to two independent proportions. This work has been accepted for publication by the Journal of Educational and Behavioral Statistics.
My other publications in the area of statistics and methodology include:
Meyerson, P., & Tryon, W. W. (2003). Validating Internet research: A test of the psychometric equivalence of Internet and in-person samples. Behavior Research Methods Instruments & Computers, 35 , 614-620.
Tryon, W. W., & Bernstein, D. (2002). Understanding measurement. In J. C. Thomas and M. Hersen (Eds.). Understanding Research in Clinical and Counseling Psychology: A textbook (pp. 27-68). Mahwah, NJ: Earlbaum.
Tryon, W. W., Orr, D. A., & Blumenfield, M. (1996). Psychometric equivalency of an electronic visual-analog (EVA), a conventional visual-analog, and a Likert rating scale. Methods in Psychiatric Research, 6, 163-167.
DeCarlo, L. T., & Tryon, W. W. (1993). Estimating and testing autocorrelation with small samples: A comparison of the C-statistic to a modified estimator. Behaviour Research and Therapy, 31, 781-788.
Fitz, D., & Tryon, W. W. (1989). Attrition and augmentation biases in time series analysis: Evaluation of clinical programs. Evaluation and Program Planning, 12, 259-270.
Tryon, W. W. (1983). Digital filters in behavioral research. Journal of the Experimental Analysis of Behavior, 39, 185-190.
Tryon, W. W. (1982). A simplified time series analysis for evaluating treatment interventions. Journal of Applied Behavior Analysis, 15, 423-429.
Connectionism and Theoretical Synthesis
Cognitive science treats the mind as a system for abstract symbol manipulation. Neuroscience takes a biological approach to brain function. Cognitive neuroscience views mind as emerging from brain function. Connectionism is a part of cognitive neuroscience that seeks to understand how layered networks give rise to psychological functions such as memory and learning which interactively support virtually other psychological processes. I find that the principles by which parallel distributed processing connectionist neural networks give rise to psychological processes provide a basis for many of the synthesis of theoretical schisms that have divided psychology into competing camps and schools. The following articles express most of my views on this subject. They are listed in chronological order because they make better sense when read in that order.
Tryon, W. W. (1993). Neural Networks: I. Theoretical Unification Through Connectionism. Clinical Psychology Review, 13, 341-352.
Tryon, W. W. (1993). Neural Networks: II. Unified Learning Theory and Behavioral Psychotherapy. Clinical Psychology Review, 13, 353-371.
Tryon, W. W. (1994). Synthesis not complementarity. American Psychologist, 49, 892-893.
Tryon, W. W. (2002). Network models contribute to cognitive and social neuroscience. American Psychologist, 57, 728.
Prueitt, P., Levine, D., Leven, S., Tryon, W. W., & Abraham, F. (1995). Introduction to artificial neural networks. In A. Gilgen and F. Abraham (Eds.), Chaos theory in psychology (pp. 195-204). Westport, CT: Praeger.
Tryon, W. W. (1995). Neural networks for behavior therapists: What they are and why they are important. Behavior Therapy, 26, 295-318.
Tryon, W. W. (1995). Resolving the cognitive behavioral controversy. the Behavior Therapist, 18, 83-86.
Tryon, W. W. (1995). Synthesizing animal and human research via neural network learning theory. Journal of Behavior Therapy and Experimental Psychiatry, 26, 303-312.
Tryon, W. W. (1995). Synthesizing psychological schisms through connectionism. In A. Gilgen and F. Abraham (Eds.), Chaos theory in psychology (pp. 247-263). Westport, CT: Praeger.
Tryon, W. W. (1996). Yes -- Neural network learning theory can resolve the behavioral-cognitive controversy. the Behavior Therapist, 19, 70, 72-73.
Tryon, W. W. (1997). Introduction to the bidirectional associative memory model: Implications for psychopathology, treatment, and research. In G. E. Stelmach & P. A. Vroon (Series Ed.) & B. Matthews (Vol. Ed.), Advances in psychology: Vol 124. Cognitive science perspectives on personality and emotion (pp. 65-122). Amsterdam, The Netherlands: Elsevier Science.
Tryon, W. W. (1998). A neural network explanation of posttraumatic stress disorder. Journal of Anxiety Disorders, 12 , 373-385.
Tryon, W. W. (1999). A bidirectional associative memory explanation of posttraumatic stress disorder. Clinical Psychology Review, 19, 789-818.
Tryon, W. W. (2000). Neural network learning theory integrates behavior therapy and behavior genetics. the Behavior Therapist, 23, 3-4, 6, 8-9, 19-20, 22.
Tryon, W. W. (2002). Contributions of connectionism to postmodern psychology. American Psychologist, 57, 455-456.
Tryon, W. W. (2002). Network models contribute to cognitive and social neuroscience. American Psychologist, 57, 728.
Tryon, W. W. (2005). Possible mechanisms for why desensitization and exposure therapy work. Clinical Psychology Review, 25, 67-95.
