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The purpose of this thesis was to determine whether asymmetry in metric and topological spatial judgments could be attributed to the spatial frequency of the stimulus or the size of the attended receptive field. A left hemisphere advantage has been found for topological judgments and a right hemisphere advantage for metric judgments. This asymmetry has been attributed to asymmetrical processing of input conditions, namely size of attended receptive field (called the attentional bin) and spatial frequency of the stimulus. The larger a stimulus, the higher the proportion of low spatial frequencies, so large stimuli are thought to facilitate the extraction of lower spatial frequencies while small stimuli are thought to facilitate the extraction of higher spatial frequencies. A left hemisphere advantage has been reported for high spatial frequencies and small attentional bins and a right hemisphere advantage has been reported for low spatial frequencies and large attentional bins. A method for pitting asymmetrically distributed input conditions against each other using asymmetrically distributed tasks was developed. Three studies were conducted. In the first study, a lack of hemisphere effects suggested bilateral processing of the stimuli. Using an eye tracker, participants were easily able to saccade to the stimulus as was shown in Experiment 2. In Experiment 3, effective exposure duration was reduced so that unilateral viewing was ensured. Under these conditions, bin size and spatial frequency were not dissociable due to a lack of hemisphere effects for spatial frequency and because of task dependency for bin size and spatial frequency processing. Although the assumptions of the double double dissociation were not met, asymmetry in spatial judgments under conditions comparable to those used by Kosslyn et al.(1989) was attributable to a right hemisphere advantage for processing through small attentional bins.

The purpose of this thesis was to determine whether asymmetry in metric and topological spatial judgments could be attributed to the spatial frequency of the stimulus or the size of the attended receptive field. A left hemisphere advantage has been found for topological judgments and a right hemisphere advantage for metric judgments. This asymmetry has been attributed to asymmetrical processing of input conditions, namely size of attended receptive field (called the attentional bin) and spatial frequency of the stimulus. The larger a stimulus, the higher the proportion of low spatial frequencies, so large stimuli are thought to facilitate the extraction of lower spatial frequencies while small stimuli are thought to facilitate the extraction of higher spatial frequencies. A left hemisphere advantage has been reported for high spatial frequencies and small attentional bins and a right hemisphere advantage has been reported for low spatial frequencies and large attentional bins. A method for pitting asymmetrically distributed input conditions against each other using asymmetrically distributed tasks was developed. Three studies were conducted. In the first study, a lack of hemisphere effects suggested bilateral processing of the stimuli. Using an eye tracker, participants were easily able to saccade to the stimulus as was shown in Experiment 2. In Experiment 3, effective exposure duration was reduced so that unilateral viewing was ensured. Under these conditions, bin size and spatial frequency were not dissociable due to a lack of hemisphere effects for spatial frequency and because of task dependency for bin size and spatial frequency processing. Although the assumptions of the double double dissociation were not met, asymmetry in spatial judgments under conditions comparable to those used by Kosslyn et al.(1989) was attributable to a right hemisphere advantage for processing through small attentional bins.

O debate da imagética mental consiste de uma controvérsia iniciada nos anos 1970 a respeito da forma das representações mentais, e foi travada principalmente entre Stephen Kosslyn, que propunha uma forma imagética, e Zenon Pylyshyn, que propunha um formato simbólico-estrutural, além de apontar falhas conceituais na teoria da afiguração implícita no modelo pictorialista. Nesta dissertação, apresenta-se um balanço filosófico deste debate, levando em conta também críticas adicionais de Daniel Dennett aos pressupostos da abordagem pictorialista. / The mental imagery debate is a controversy that began in the 1970s concerning the form of mental representation, and was carried out mainly by Stephen Kosslyn, who defended a picture-like representation, and Zenon Pylyshyn, who proposed a symbolic-structural format. The latter also pointed out conceptual problems of the pictorialist model. This thesis presents a philosophical discussion of the debate, also taking into account additional criticisms by Daniel Dennett to the presuppositions of the pictorialist approach.

O debate da imagética mental consiste de uma controvérsia iniciada nos anos 1970 a respeito da forma das representações mentais, e foi travada principalmente entre Stephen Kosslyn, que propunha uma forma imagética, e Zenon Pylyshyn, que propunha um formato simbólico-estrutural, além de apontar falhas conceituais na teoria da afiguração implícita no modelo pictorialista. Nesta dissertação, apresenta-se um balanço filosófico deste debate, levando em conta também críticas adicionais de Daniel Dennett aos pressupostos da abordagem pictorialista. / The mental imagery debate is a controversy that began in the 1970s concerning the form of mental representation, and was carried out mainly by Stephen Kosslyn, who defended a picture-like representation, and Zenon Pylyshyn, who proposed a symbolic-structural format. The latter also pointed out conceptual problems of the pictorialist model. This thesis presents a philosophical discussion of the debate, also taking into account additional criticisms by Daniel Dennett to the presuppositions of the pictorialist approach.

Internal consistency reliability and validity were established for a new 31 item Imagery Manipulation Scale. Previous attempts to correlate subjectively rated control of visual imagery with tests of spatial ability have been unsuccessful. However, no attempt to construct a subjectively rated control of imagery scale was located which tried to establish internal consistency reliability and both content and construct validity. Further, no research was located in which subjects were requested to rate their imagery ability utilized during the performance of the actual spatial tasks used to try to establish validity. A new scale of subjectively rated control of imagery was devised in which subjects were requested to rate their imagery while solving spatial tasks which involved visualizing the manipulation of geometric forms. Content validity was established by analyzing the transformation involved while solving the spatial problems. Internal consistency reliability for the 31 item scale was established across two samples. Validity was established with the second sample (100 university students: 26 male and 74 female). The task utilized to provide validity could be objectively scored, and was made up of four spatial subtests, which were adapted from the Vandenberg and Kuse Mental Rotations Test, the Kosslyn Directions Test, performed in both the forward and backward direction, and a block task utilized by Snyder. A convergent and discriminant validity analysis established construct validity. Further, the hypotheses of three investigators, Kosslyn, Shepard and his colleagues, and Snyder, were supported by the results of the present investigation, thus substantiating the conclusion that reported control of imagery processing can be operationalized with performance scores on spatial ability tasks.