PubMed · 3661675
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M A Bullimore, B Gilmartin. 1987. Retinal eccentricity and the accommodative response.. https://pubmed.ncbi.nlm.nih.gov/3661675/
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Goal-directed actions are guided by expected outcomes of those actions. Humans with bilateral damage to ventromedial prefrontal cortex, or the amygdala, are deficient in their ability to use information about positive and negative outcomes to guide their choice behavior. Similarly, rats and monkeys with orbital prefrontal or amygdala damage have been found to be impaired in their responses to changing values of outcomes. In the present study, we tested whether direct, functional interaction between the amygdala and the orbital prefrontal cortex is necessary for guiding behavior based on expected outcomes. Unlike control monkeys, rhesus monkeys with surgical disconnection of these two structures, achieved by crossed unilateral lesions of the amygdala in one hemisphere and orbital prefrontal cortex in the other, combined with forebrain commissurotomy, were unable to adjust their choice behavior after a change in the outcome (here, a reduction in the value of a particular reinforcer). The lesions did not affect motivation to work for a food reinforcer, or food preferences, per se. Hence, the amygdala and orbital prefrontal cortex act as part of an integrated neural system guiding decision-making and adaptive response selection.
An old explanation of the moon illusion holds that various cues place the horizon moon at an effectively greater distance than the elevated moon. Although both moons have the same angular size, the horizon moon must be perceived as larger. More recent explanations hold that differences in accommodation or other factors cause the elevated moon to appear smaller. As a result of this illusory difference in size, the elevated moon appears to be more distant than the horizon moon. These two explanations, both based on the geometry of stereopsis, lead to two diametrically opposed hypotheses. That is, a depth interval at a long distance is associated with a smaller binocular disparity, whereas an equal depth interval at a smaller distance is associated with a larger disparity. We conducted experiments involving artificial moons and confirmed the hypothesis that the horizon moon is at a greater perceptual distance. Moreover, when a moon of constant angular size was moved closer it was also perceived as growing smaller, which is consistent with the older explanation. Although Emmert's law does not predict the size-distance relationship over long distances, we conclude that the horizon moon is perceived as larger because the perceptual system treats it as though it is much farther away. Finally, we observe that recent explanations substitute perceived size for angular size as a cue to distance. Thus, they imply that perceptions cause perceptions.
UNLABELLED: To study motor and sensory responses in vertical fusion at different angles of horizontal vergence in normal humans. METHODS: The study included 12 normal subjects. A cross (+) extending 3.4 degrees x3.2 degrees was presented dichoptically. Vertical disparity was introduced by changing the vertical position of the cross in front of one eye. The disparity was incremented by 0.08 degrees every 8 s. Distance viewing was tested with 1 degrees of convergence demand, near vision with 6-15 degrees convergence demand. Eye movements were recorded using three-axis search coils. RESULTS: Vertical fusion capability was larger at near vision than at distance in 9 of 12 subjects. For the entire group, total vertical fusion capability (motor plus sensory response) differed between distance (mean 1.68 degrees ) and near (mean 2.39 degrees ). The motor component differed significantly between distance (mean 1.42 degrees ) and near (mean 2.13 degrees ). No difference in the sensory component was seen between distance (mean 0.26 degrees ) and near (mean 0.27 degrees ). CONCLUSIONS: Vertical fusion capability increases with convergence. This increase is mainly due to an increase of the motor response.