Binocular unmasking with unequal interocular contrast: The case for multiple Cyclopean eyes

Under certain conditions, the detection threshold for a sinusoidal grating embedded in a noisy background may be an order of magnitude lower when binocular cues are available than when monocular cues only are present. Such binocular unmasking occurs only when the degree of interocular disparity for the target differs from that of the background. Two classes of models have been advanced to account for such unmasking. The first assumes that orientation-specific, spatial frequency channels in each eye encode the amplitude and phase of the spatial frequency component of the pattern the channel is tuned to detect. Thus, a difference in interocular disparity between target and background could result in interocular amplitude and/or phase differences in left- and right-eye spatial frequency channels. When, however, there are no disparity differences between target and background, there will be no interocular differences in amplitude and phase in the left- and right-eye channels. In this model, then, binocular unmasking reflects the binocular system’s ability to respond to interocular amplitude and/or phase differences in the patterns presented to the two eyes. In the second class of models, it is assumed that the left and right-eye patterns are first summed to form a “Cyclopean” eye. In these models, detection depends on the effect this summation process has on the power spectrum of the summated patterns. To decide between these two classes of models, we observed the occurrence of binocular unmasking when (1) the contrast of masker and signal was varied identically in both eyes and (2) the contrast of masker and signal was varied in one eye only. Consistent with our previous research, we found that the results can be accounted for in terms of a linear summation model of binocular unmasking; the alternative interocular phase detection model was disproved. The implications of these findings for binocular contrast summation in the absence of visual noise are discussed.     

Binocular vision enhances phase discrimination by filtering the background

Previous studies have shown that the detectability of a noise-masked target can be enhanced under stereoscopic viewing when the target’s interocular disparity differs from that of the noise. This enhanced detectability can be accounted for by a model postulating that the binocular system linearly sums the left-eye and right-eye views of a visual scene. This model also predicts enhanced phase discrimination under specifiable interocular disparities of target and noise. Two experiments were conducted in which subjects were asked to discriminate between two luminance patterns (target and foil) that differed only in phase. The target patterns were constructed by summating two vertical sinusoidal gratings in which the phase difference between the higher and the lower spatial frequency gratings was 45°. The foils contained the same two component frequencies, with a phase difference of ?45°. Thus, targets and foils were mirror images of one another. The ability of subjects to Discriminate between these stereoscopically viewed mirror-image patterns was investigated under two sets of interocular disparities: those that, according to our model, would unmask one or both spatial frequency components, and those that would leave both components masked by the noise. Phase discrimination was enhanced only when both component frequencies of the target and foil were unmasked. The implications of these findings for template-matching and phase-discrimination models of pattern discrimination are considered.     

A comparison of higher order auditory processes in younger and older adults

The authors conducted 3 experiments investigating the effects of aging on higher order auditory processes. They compared younger and older adults with respect to (a) their auditory channel capacity, (b) the extent of their top-down control over auditory gain, and (c) their ability to focus attention on a narrow band of frequencies. To ensure that subclinical cochlear processing deficits in older adults (e.g., higher thresholds, poorer discrimination of frequency and intensity differences) did not limit performance, the authors used only stimuli that were perfectly discriminable by all participants. No age differences were found in any of these experiments, suggesting that some higher order auditory processes (e.g., top-down control over auditory gain, auditory attention) are preserved in normal aging, despite numerous age-related declines in peripheral auditory functionality.     

Disorganized Narratives: Problems In Treatment And Therapist Intervention Hierarchy

The way in which patients tell therapists their stories has an impact on treatment. They try to put their emotions and the events generating them, their goals and the behavior they adopt to achieve them, and so on, together in a coherent discourse. But some patients fail in organizing their narratives. They might describe a diffuse arousal without letting the reasons for their discomfort be known, switch from one subject to another without any apparent connection, or pile up one topic after another, thus overwhelming a listener, who is unable to see which is the main one. We call such narratives disorganized. They do not help a patient to make sense of experience or achieve consistency in behavior. A therapist listening has difficulty in planning treatment and often reacts negatively to such patients. Here we propose a series of interventions aimed at improving narrative coherence, creating a sound therapeutic relationship and making treatment effective. We will describe the therapy with a seriously dissociated patient in which this intervention has proven useful.     

General principles for treating personality disorder with a prominent inhibitedness trait: towards an operationalizing integrated technique

Psychotherapists need to perform tasks such as being empathetic, performing an ongoing assessment of cases, self-disclosing, making explicit treatment contracts, validating patients' experiences and promoting awareness of psychological experience, if they are to be effective in treating personality disorder (PD). Successful therapy also requires a systematic accurate PD model. We suggest here that it is still unclear how, when, and according to what session markers therapists need to perform specific operations to maximize therapeutic gains. This article describes and operationalizes a step-by-step procedure for organizing and delivering the interventions necessary for effective outcomes, such as maintaining a good therapeutic relationship, increasing understanding of mental states, reducing symptoms and improving social adaptation. The procedure is illustrated by reference to the treatment of cases of emotionally overly-constricted PDs. We include a theoretical proposal to facilitate the development of measures for evaluating the efficacy of therapist actions.