In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated und... more In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated under some conditions by a second, non-overlapping brief stimulus (the mask). In Type-A masking, target visibility is low when mask and target onset simultaneously (stimulus onset ...
Human listeners can effortlessly categorize a wide range of environmental sounds. Whereas categor... more Human listeners can effortlessly categorize a wide range of environmental sounds. Whereas categorizing visual object classes (e.g., faces, tools, houses, etc.) preferentially activates different regions of visually sensitive cortex, it is not known whether the auditory system exhibits a similar organization for different types or categories of complex sounds outside of human speech. Using functional magnetic resonance imaging, we show that hearing and correctly or incorrectly categorizing animal vocalizations (as opposed to handmanipulated tool sounds) preferentially activated middle portions of the left and right superior temporal gyri (mSTG). On average, the vocalization sounds had much greater harmonic and phase-coupling content (acoustically similar to human speech sounds), which may represent some of the signal attributes that preferentially activate the mSTG regions. In contrast, correctly categorized tool sounds (and even animal sounds that were miscategorized as being tool-r...
To identify the brain regions preferentially involved in environmental sound recognition (compris... more To identify the brain regions preferentially involved in environmental sound recognition (comprising portions of a putative auditory ‘what’ pathway), we collected functional imaging data while listeners attended to a wide range of sounds, including those produced by tools, animals, liquids and dropped objects. These recognizable sounds, in contrast to unrecognizable, temporally reversed control sounds, evoked activity in a distributed network of brain regions previously associated with semantic processing, located predomi-nantly in the left hemisphere, but also included strong bilateral activity in posterior portions of the middle temporal gyri (pMTG). Comparisons with earlier studies suggest that these bilateral pMTG foci partially overlap cortex implicated in high-level visual processing of complex biological motion and recognition of tools and other arti-facts. We propose that the pMTG foci process multimodal (or supramodal) information about objects and object-associated motion,...
Abstract. Object recognition was studied in human subjects to determine whether the storage of th... more Abstract. Object recognition was studied in human subjects to determine whether the storage of the visual objects was in a two-dimensional or a three-dimensional representation. Novel motionbased and disparity-based stimuli were generated in which three-dimensional and two-dimensional form cues could be manipulated independently. Subjects were required to generate internal representations from motion stimuli that lacked explicit two-dimensional cues. These stored internal representations were then matched against internal three-dimensional representations constructed from disparity stimuli. These new stimuli were used to confirm prior studies that indicated the primacy of two-dimensional cues for view-based object storage. However, under tightly controlled conditions for which only three-dimensional cues were available, human subjects were also able to match an internal representation derived from motion to that of disparity. This last finding suggests that there is an internal stor...
Various models of personhood exist within Christianity. These often involve a particular understa... more Various models of personhood exist within Christianity. These often involve a particular understanding of the human soul. We believe that three common assumptions about the soul are incorrect and may lead to errors in Christian praxis. These assumptions are that the soul (1) is instantaneously created at the moment of fertilization, (2) is immaterial and pure and somehow better than the body, and (3) is the “real person.” Using insights from biology, we suggest a new perspective that we call “developing hominization.” Our model is open regarding anthropological monism or dualism. However, we seek to clarify Christian anthropology by stipulating that models employing the foregoing beliefs must be changed or eliminated since they do not meet philosophical, scriptural, and practical qualification to properly inform our understanding of personhood and all its ramifications in theology and science. We examine, through examples, how our model would better inform Christian praxis.
Our ability to manipulate and understand the use of a wide range of tools is a feature that sets ... more Our ability to manipulate and understand the use of a wide range of tools is a feature that sets humans apart from other animals. In right-handers, we previously reported that hearing hand-manipulated tool sounds preferentially activates a left hemisphere network of motor-related brain regions hypothesized to be related to handedness. Using functional magnetic resonance imaging, we compared cortical activation in strongly right-handed versus left-handed listeners categorizing tool sounds relative to animal vocalizations. Here we show that tool sounds preferentially evoke activity predominantly in the hemisphere "opposite" the dominant hand, in specific high-level motor-related and multisensory cortical regions, as determined by a separate task involving pantomiming tool-use gestures. This organization presumably reflects the idea that we typically learn the "meaning" of tool sounds in the context of using them with our dominant hand, such that the networks underlying motor imagery or action schemas may be recruited to facilitate recognition.
The range of spatial displacements over which cyclopean (stereoscopic) apparent motion is perceiv... more The range of spatial displacements over which cyclopean (stereoscopic) apparent motion is perceived was investigated. The cyclopean stimuli were created from retinal disparity embedded in dynamic random-dot stereograms. In one experiment, the displacement range for crossed-disparity cyclopean motion was compared with that for luminance-domain motion. The results showed that cyclopean motion was perceived over spatial displacements that were about two to three times larger than the displacements over which luminance motion was perceived. In a second experiment, the displacement range for crossed-disparity cyclopean motion was compared with that for uncrossed-disparity cyclopean motion. The results revealed that the displacement range was restricted (motion quality was poor) for uncrossed motion relative to crossed motion. It is inferred that cyclopean motion from crossed disparity is represented at a coarse spatial scale, relative to luminance motion, and that cyclopean motion from uncrossed disparity is suppressed due to occlusion cues present when uncrossed stimuli are seen behind a textured background.
In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated und... more In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated under some conditions by a second, non-overlapping brief stimulus (the mask). In Type-A masking, target visibility is low when mask and target onset simultaneously (stimulus onset ...
In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated und... more In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated under some conditions by a second, non-overlapping brief stimulus (the mask). In Type-A masking, target visibility is low when mask and target onset simultaneously (stimulus onset ...
Human listeners can effortlessly categorize a wide range of environmental sounds. Whereas categor... more Human listeners can effortlessly categorize a wide range of environmental sounds. Whereas categorizing visual object classes (e.g., faces, tools, houses, etc.) preferentially activates different regions of visually sensitive cortex, it is not known whether the auditory system exhibits a similar organization for different types or categories of complex sounds outside of human speech. Using functional magnetic resonance imaging, we show that hearing and correctly or incorrectly categorizing animal vocalizations (as opposed to handmanipulated tool sounds) preferentially activated middle portions of the left and right superior temporal gyri (mSTG). On average, the vocalization sounds had much greater harmonic and phase-coupling content (acoustically similar to human speech sounds), which may represent some of the signal attributes that preferentially activate the mSTG regions. In contrast, correctly categorized tool sounds (and even animal sounds that were miscategorized as being tool-r...
To identify the brain regions preferentially involved in environmental sound recognition (compris... more To identify the brain regions preferentially involved in environmental sound recognition (comprising portions of a putative auditory ‘what’ pathway), we collected functional imaging data while listeners attended to a wide range of sounds, including those produced by tools, animals, liquids and dropped objects. These recognizable sounds, in contrast to unrecognizable, temporally reversed control sounds, evoked activity in a distributed network of brain regions previously associated with semantic processing, located predomi-nantly in the left hemisphere, but also included strong bilateral activity in posterior portions of the middle temporal gyri (pMTG). Comparisons with earlier studies suggest that these bilateral pMTG foci partially overlap cortex implicated in high-level visual processing of complex biological motion and recognition of tools and other arti-facts. We propose that the pMTG foci process multimodal (or supramodal) information about objects and object-associated motion,...
Abstract. Object recognition was studied in human subjects to determine whether the storage of th... more Abstract. Object recognition was studied in human subjects to determine whether the storage of the visual objects was in a two-dimensional or a three-dimensional representation. Novel motionbased and disparity-based stimuli were generated in which three-dimensional and two-dimensional form cues could be manipulated independently. Subjects were required to generate internal representations from motion stimuli that lacked explicit two-dimensional cues. These stored internal representations were then matched against internal three-dimensional representations constructed from disparity stimuli. These new stimuli were used to confirm prior studies that indicated the primacy of two-dimensional cues for view-based object storage. However, under tightly controlled conditions for which only three-dimensional cues were available, human subjects were also able to match an internal representation derived from motion to that of disparity. This last finding suggests that there is an internal stor...
Various models of personhood exist within Christianity. These often involve a particular understa... more Various models of personhood exist within Christianity. These often involve a particular understanding of the human soul. We believe that three common assumptions about the soul are incorrect and may lead to errors in Christian praxis. These assumptions are that the soul (1) is instantaneously created at the moment of fertilization, (2) is immaterial and pure and somehow better than the body, and (3) is the “real person.” Using insights from biology, we suggest a new perspective that we call “developing hominization.” Our model is open regarding anthropological monism or dualism. However, we seek to clarify Christian anthropology by stipulating that models employing the foregoing beliefs must be changed or eliminated since they do not meet philosophical, scriptural, and practical qualification to properly inform our understanding of personhood and all its ramifications in theology and science. We examine, through examples, how our model would better inform Christian praxis.
Our ability to manipulate and understand the use of a wide range of tools is a feature that sets ... more Our ability to manipulate and understand the use of a wide range of tools is a feature that sets humans apart from other animals. In right-handers, we previously reported that hearing hand-manipulated tool sounds preferentially activates a left hemisphere network of motor-related brain regions hypothesized to be related to handedness. Using functional magnetic resonance imaging, we compared cortical activation in strongly right-handed versus left-handed listeners categorizing tool sounds relative to animal vocalizations. Here we show that tool sounds preferentially evoke activity predominantly in the hemisphere "opposite" the dominant hand, in specific high-level motor-related and multisensory cortical regions, as determined by a separate task involving pantomiming tool-use gestures. This organization presumably reflects the idea that we typically learn the "meaning" of tool sounds in the context of using them with our dominant hand, such that the networks underlying motor imagery or action schemas may be recruited to facilitate recognition.
The range of spatial displacements over which cyclopean (stereoscopic) apparent motion is perceiv... more The range of spatial displacements over which cyclopean (stereoscopic) apparent motion is perceived was investigated. The cyclopean stimuli were created from retinal disparity embedded in dynamic random-dot stereograms. In one experiment, the displacement range for crossed-disparity cyclopean motion was compared with that for luminance-domain motion. The results showed that cyclopean motion was perceived over spatial displacements that were about two to three times larger than the displacements over which luminance motion was perceived. In a second experiment, the displacement range for crossed-disparity cyclopean motion was compared with that for uncrossed-disparity cyclopean motion. The results revealed that the displacement range was restricted (motion quality was poor) for uncrossed motion relative to crossed motion. It is inferred that cyclopean motion from crossed disparity is represented at a coarse spatial scale, relative to luminance motion, and that cyclopean motion from uncrossed disparity is suppressed due to occlusion cues present when uncrossed stimuli are seen behind a textured background.
In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated und... more In metacontrast masking, perception of a brief stimulus (the target) is reduced or eliminated under some conditions by a second, non-overlapping brief stimulus (the mask). In Type-A masking, target visibility is low when mask and target onset simultaneously (stimulus onset ...
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