The role of discontinuities in the perception of subjective figures

Recently we proposed a theory of visual interpolation (Kellman & Shipley, in press) that addresses a variety of unit formation phenomena, including the perception of partly occluded objects and subjective figures. A basic notion of the theory is that discontinuities in the first derivative of projected edges are the initiating conditions for interpolation of boundaries that are not physically specified. In this paper, we report four experiments in which this claim was tested in the domain of subjective figures. Experiments 1 and 2 demonstrate that discontinuities in the first derivative of the edges of inducing elements have a clear effect on the frequency of report and the perceived clarity of simple subjective figures. Similar effects are found when unfamiliar subjective figures and inducing elements are used (Experiment 3). Experiment 4 rules out the possibility that the discontinuities in the first derivative merely add to the clarity of subjective figures. These experiments suggest that first-order discontinuities play a central role in unit formation.     

Relationship of induced motion and apparent straight-ahead shifts to optokinetic stimulus velocity

Induced motion (IM) of a fixated spot stimulus and shifts of the apparent straight-ahead (ASA) from the objective median plane were studied as a function of the velocity of a full-field optokinetic background stimulus. Both IM and ASA were influenced similarly by changes in stimulus velocity. The magnitude of both responses, averaged across subjects, increased to a peak level with background velocities of 40-80 deg/sec and decreased at higher velocities. Individual subjects differed with respect to the precise functions by which IM and ASA shifts were related to stimulus velocity. However, for individual subjects, the effects of velocity on IM and ASA shifts were typically highly correlated. Although IM is correlated with shifts of ASA in the opposite direction, the magnitude of the ASA shift is insufficient to account for the observed IM.     

Stochastic analysis of the duration of the speaker role in psychotherapy

An analysis has been undertaken of the stochastic behavior of the time series which defines the duration of utterances exchanged by patients and therapists in six recorded sessions of psychotherapy. Each series followed a Box-Jenkins time series model of order (1, 0, 0): that is, each behaved as a first-order autoregressive process, sensitive to the prior state of the system. The confidences associated with the parameters of the autoregressive models were very high. In addition, the histograms of length of each utterance indicated an underlying Poisson model for the emergence of speech. The parameters of the Poisson and autoregressive models varied with each patient/therapist pair. Signatures for the process dynamics of the speaker-role variable were obtained. The two analyses suggest fundamental structures within the psychotherapeutic dialogue. The Box-Jenkins results provide a global summary of the inner structure of the series and its progression, while the Poisson results describe its instantaneous behavior. This work is offered as a part of new efforts to apply scientific and mathematical methods to the psychotherapeutic domain.     

Concurrent validity of the motor domain of the Vineland Adaptive Behavior Scales

The concurrent validity of the motor domain from the Vineland Adaptive Behavior Scales was estimated using scores from the Peabody Developmental Motor Scales as criteria. A moderately high correlation between the measures was obtained. Implications, particularly for preschool children, were discussed.     

Insulin and dextrose effects on fixed-interval behavioral thermoregulation in albino rats

This study is a systematic replication of the effects of insulin doses on operant behavior reinforced (in an earlier study) by fixed-ratio schedules of microwave (MW) reinforcement. In this study, insulin and dextrose doses were administered (ip) prior to fixed-interval 2-min. schedules of MW reinforcement in rats tested in a cold environment. Six Sprague-Dawley rats were conditioned to regulate their thermal environment with 5-sec. exposures of MW radiation (SAR = 0.34 Watts/kg/(mW/cm2) under the FI-2' schedules. Humulin-regular insulin and 50% solutions of dextrose were administered (ip) alternately with saline control sessions for 8-hr. durations. A within-subjects, repeated-measures 4 x 8 x 3 factorial analysis of variance design showed that insulin doses suppressed operant responding for heat, which confirmed the results of the earlier study under a different schedule. In addition, high doses of dextrose had similar suppressing effects on operant responding for heat. The data are interpreted in terms of the discriminative properties of increased thermogenesis produced by the insulin and dextrose doses. The suppressing effects were more pronounced for the first two hours, yet they persisted for approximately six hours of the 8-hr. sessions.     

Is eye movement dysfunction a biological marker for schizophrenia? A methodological review

There is a high prevalence of eye movement dysfunction (EMD) in persons with schizophrenia and their first-degree relatives. Studies addressing the prevalence, stability, familial transmission, and psychological correlates of EMD in persons from both psychiatric and general populations offer suggestive evidence that this abnormality may serve as a biological marker for schizophrenia. Although these findings are promising, their significance for elucidating the diagnostic bandwidth, pathophysiology, and genetics of this disorder remains to be determined. More precise characterization of ocular motility, perhaps when used in conjunction with global measures of pursuit adequacy, may be essential for clarifying the pathophysiological and genetic significance of EMD for schizophrenia. Recent research efforts are beginning to identify particular abnormalities that could serve as more specific biological markers for schizophrenia.     

Alcohol challenge with sons of alcoholics: a critical review and analysis

Studies are reviewed in which response to acute administration of alcohol was compared between individuals with and without family histories of alcoholism (FH+, FH-). This research represents a search for a psychobiological marker for alcoholism. A methodological critique of the procedures reported in this literature is then presented. Finally, a conceptual model is suggested in which differences in the response to alcohol between FH+ individuals and FH- individuals must be understood in relation to time after drinking alcohol. This Newtonian differentiator model proposes that sons of alcoholics exhibit acute sensitization as blood alcohol level rises and acute tolerance as blood alcohol level falls, compared with sons of nonalcoholics. Therefore, FH+ subjects find alcohol more rewarding because they accentuate the pleasurable, excitatory aspects of initial intoxication and attenuate the feelings of anxiety and depression that predominate as blood alcohol levels drop.     

Marital conflict and children's adjustment: a cognitive-contextual framework

Marital problems have been related to numerous indexes of maladjustment in children. Although several parameters of this association have been identified, the process by which exposure to interparental conflict gives rise to adjustment problems in children is largely unexplored. Research on the link between marital conflict and child maladjustment therefore is critically evaluated, and a framework is presented that organizes existing studies and suggests directions for future research on processes that may account for the association. According to the framework, the impact of marital conflict is mediated by children's understanding of the conflict, which is shaped by contextual, cognitive, and developmental factors. The implications of the framework for children's adjustment are discussed.