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About neural implementation and microgenesis
Cognitive Contributions to the Perception of Spatial and Temporal Events G. Aschersleben, T. Bachmann, and J. Miisseler (Editors) 1999 Elsevier Science B.V.
About Neural Implementation and Microgenesis Commentary on Tsal
TalisBachmann Department of Psychology, University of Portsmouth, Un#ed Kingdom The main contribution of Tsal's paper consists in providing a strong and varied evidence for the facilitative effect of spatial selective attention on spatial discrimination. Another interesting empirical aspect relates to the finding that with unfocused spatial attention, the visual system creates certain perceptual illusions that are related to the poor spatial discrimination: overestimation of line length and the tendency to close small gaps within the extended visual objects. Tsal puts forward a theoretical construct to explain these effects - attentional receptive fields. Both the data reviewed and theory offered are highly valuable for the development of our understanding of visual cognition and advanced applied research in ergonomics. As follows, there will be few comments I would like to make with regard to the theoretical context Tsal's contribution might fit in.
1
Attentional Receptive Fields and Other Concepts of Spatial Attention
The conceptualisation put forward by Tsal is by no means the only one that relates selective attention to spatial resolution. One of the central notions of the zoom lens model by Eriksen (e.g., Eriksen & StJames, 1986) states that if attention is drawn to a spatial area, then its focus is initially large, but gradually "zooms in" at the designated region. Eriksen hypothesised that the larger the focus, the poorer the resolution within the focus and vice versa. Most of the data by Tsal is consistent with this theory. As a result of the putative zooming-in, spatial resolution increases and observers are better able to detect the gaps and localise the objects. The overestimation of size, however, becomes more difficult a problem for the zoom lens model. One would assume that observers would err in both directions with attention being spatially unfocused (or even tend to make more mistakes in the direction of underestimating the s i z e - the larger the focus, the relatively smaller the object may seem according to the contrast effect). In this respect, Tsal's model has an advantage over the zoom-lens model. In a recent study, Bachmann and Kahusk (1997) did find that precuing of spatially quantised target images caused different effects depending on the spatial scale of quantisation. Identification of the fine-quantised target images did not change much or was facilitated by attentional precuing. With coarse-quantised target images there
168 Talis Bachmann was a cost ofprecuing, however: preliminary focusing of attention had a detrimental effect on target identification. We explained this as a result of the effective spatialattentional routine, according to which attention gradually helps to activate perceptual representations, beginning with coarse levels of image description and proceeding on at the fine, detailed levels. The hypothesis of attentional receptive fields is not at odds with this. If precues cause attentional focusing that results in the activation of the fine-tuned (small) receptive fields, then what dominates perceptual representation at the moment when focusing is effected will be primarily the fine-scale image description. In case of coarse-quantised images, the fine scales carry only misleading information about pixel edges and corners, which explains the cost of precuing. This notion would require further development of Tsal's theory so as to involve the timecourse aspect of the activity of attentional receptive fields, however. In an important paper on the "crowding effect", He, Cavanagh, and Intriligator (1996) found that observers who were able to discriminate the small patches of variously oriented gratings if the patches were exposed in isolation, lost discrimination sensitivity if the same stimuli were presented among the spatially neighbouring, distractor, items. Importantly, single-cell recordings revealed that irrespective of the discrimination in explicit perceptual representation, visual cortical neurones that were tuned to the target stimuli kept responding in the same manner whether in "crowding" conditions or not. This is a piece of evidence proving that processing of the stimulus-specific information at the cortical level can be functionally independent of the attentive perception at the phenomenal level. This result is ambiguous with regard to the Tsal's theory. On the one hand, He et al.'s (1996) findings add credibility to Tsal's hypothesis by showing that not only the low-level visual receptive fields matter in phenomenal representation of spatial stimulus-information, but that some other (further?) processes related to parallel versus serial processing and/or limited capacity (attention?) should be important. On the other hand, the findings by He and his colleagues, by the virtue of showing precisely the neural equivalent for "preconscious" sensory discrimination, at the same time stress the lack of this kind of neurophysiological specificity in the Tsal's concept of attentional receptive fields. Computationally, the theory is apt. Neurophysiologically- unproven. Most of the existing neurophysiological evidence for the neural correlates of attentional processes seems to point towards the relatively poor spatial resolution of the neural systems that service spatial selective attention. For example, in the seminal works by Wurtz and his colleagues (e.g., Goldberg & Wurtz, 1972; Wurtz, Goldberg, & Robinson, 1980) superior colliculus' and cortical neurones have been found, the activity of what strongly correlates with covert orienting of spatial attention. These neurones, however, have receptive fields that are not as much finetuned as are the receptive fields of the neurones for perceptual stimulus representation proper. In several approaches nonspecific thalamic neurones have been described to fulfil the functions of focal attention (Scheibel, 1981; Scheibel & Scheibel, 1967, 1970; Crick, 1984; LaBerge, 1995; Bachmann, 1999). As a rule, the size of the receptive fields of the thalamic "orienting" and "awareness-related" neuronal systems is much larger than that of the specific, sensory-representational, system. All this contradicts the theory of attentional receptive fields which assumes just the opposite better spatial resolution for the attentional receptive fields in comparison with the
-
Commentary on Tsal 169 perceptual receptive fields without attentional involvement. How to solve this seeming contradiction? First, one might assume that Tsal will provide us with some direct neurophysiological evidence showing how the neurones which are the intimate part of some known attentional system evidence higher spatial discrimination power in comparison with the neurones of perceptual systems that are neuroanatomically independent of the attentional system. Second,- and this is my personal favouriteit may be more realistic to hope find that any anatomically distinct, exclusively attentional, neural system which has receptive fields with extremely good spatial resolution does not exist. What could happen instead is a spatial fine-tuning of the perceptual representational neurons under the effects of attention, with these neurons working much better in terms of spatial resolution if the nonspecific attentional modulation is applied. The neural structural correlate of the attentional receptive fields may not exist, but the functional correlate in terms of the interaction of the nonspecific attentional systems with the specific representational systems might be found. In my perceptual retouch conceptualisation (Bachmann, 1999) the positive effect of attention on the spatial resolution can be explained as follows. In order to guarantee good spatial resolution, the specific representational neurons should be active as a "full set". Most of the neurons that represent a perceptual object should be involved in building up or re-activating the representation. Involvement of attention facilitates nonspecific modulation of the activity of the specific representational neurons. As a result, the number of active neurons increases, and the signalto-noise ratio of the activity of the neurons that stand for the actually exposed object increases as well. The effect of overestimation of size could be the result of the prevalence of the activity of the neurons that mediate coarse levels of image description, given that attentional modulation has not been applied properly. 2
Microgenetic Perspective on Spatial Resolution and Size Estimation
It seems to me that Tsal's approach would benefit from the data and theoretical conceptions put forward from within the microgenetic approach to visual object perception in general and size estimation in particular. This approach assumes that percepts do not emerge instantly in their final form, but that percepts unfold in real time featuring several different, qualitatively distinct, stages (Lange, 1893; Sander, 1962; Werner, 1957; Flavell & Draguns, 1957; Vekker, 1974; Fr6hlich, 1984; Brown, 1988; Bachmann, 1977, 1991, 1998). Perhaps the most common findings have been that global (coarse) levels of perceptual object description precede the local (detailed, fine) levels of description (Navon, 1977; Bachmann, 1987; Kimchi, 1992; Sanocki, 1993; Parker, Lishman, & Hughes, 1997; Hughes, Fendrich, & Reuter-Lorenz, 1990; Hughes, Nozawa, & Kitterle 1996)and that the preceding, brief stimuli can influence the speed and qualitative aspects of the percept formation for the succeeding stimuli (Calis, Sterenborg, & Maarse, 1984; Bachmann, 1989; Klotz & Wolff, 1995; Sekuler & Palmer, 1992). Generally less known is the tradition to study the microgenesis of size perception. As Howard (1972), Erlebacher and Sekuler (1974), Holt-Hansen (1975, 1980), and Nakatani (1995)have demonstrated, the perceived size of a briefly presented stimulus is initially underestimated, but develops microgenetically over time.
170 Talis Bachmann At about 200 ms after the stimulus onset, the under-estimation may sometimes give place to over-estimation. It would be therefore useful if Tsal would consider both the effects of stimulus exposure duration and precue-to-target SOA on the results of his experiments. Only if these factors are systematically accounted for, one can be sure about the generality and validity of the results and their theoretical interpretations.
3
Conclusions
It seems that Tsal has suggested a potentially very useful concept, that of attentional receptive fields, that is consistent with a multitude of empirical facts about the attentional effects on spatial discrimination. The main elements of the theory (such as the location detectors and overlapping receptive fields with their strong computational potential) are consistent both with the empirical facts from the psychophysics of attention and standard requirements for cognitive architectures in the context of computational approaches. What remains to be done, however, is to show that and how these abstract concepts relate to the neurophysiological reality of perceptualattentional processing. Also, what stands behind the "assessment" of the activation levels of detectors in terms of the underlying neurophysiology? The main issue will undoubtedly be the distinction between the structural and functional varieties of the pending neuroreductionist explanation for attentional-perceptual (pertentional?) interaction. Even if the neurophysiological reality would contradict the notion of structurally distinct units that subserve fine-tuned attentional receptive fields, the concept suggested by Tsal can still be useful in the applied contexts. I am quite enthusiastic about the possibility to address also the question of perceptual microgenesis to show that the putative effects of the attentional receptive fields are not the artefactual outcomes of the variation in the microgenetic processes as a result of attentional manipulations. But then, maybe, microgenesis is the temporal dynamics of the employment of attentional receptive fields?
References Bachmann T. (1977). Contemporary psychophysics, phenomenology of experiment, and visual information processing. Acta et Commentationes Universitatis Tartuensis, #429, Studies in Psychology VI, 11-33. [in Russian] Bachmann, T. (1987). Different trends in perceptual pattern microgenesis as a function of the spatial range of local brightness averaging. Psychological Research, 49, 107-111. Bachmann, T. (1989). Microgenesis as traced by the transient paired-forms paradigm. Acta Psychologica, 70, 3-17. Bachmann T. (1991). Microgenesis in visual information processing: Some experimental results. In R. E. Hanlon (Ed.), Cognitive microgenesis. A neuropsychological perspective. (pp. 240-261). New York: Springer-Verlag. Bachmann, T. (1998). Is conscious experience established instantaneously? Commentary on Taylor. Consciousness and Cognition, 7, 149-156.
Commentary on Tsal 171 Bachmann, T. (1999). Twelve spatiotemporal phenomena and one explanation. In G. Aschersleben, T. Bachmann, & J. Mtisseler (Eds.), Cognitive contributions to the perception of spatial and temporal events. Amsterdam: Elsevier (this volume). Bachmann, T., & Kahusk, N. (1997). The effects of coarseness of quantisation, exposure duration, and selective spatial attention on the perception of spatially quantised ("blocked") visual images. Perception, 26, 1181-1196. Brown, J. (1988). The life of the mind. Hillsdale, NJ: Erlbaum. Calis, G., Sterenborg, J., & Maarse, F. (1984). Initial microgenetic steps in single-glance face recognition. Acta Psychologica, 55, 215-230. Crick, F. (1984). Function of the thalamic reticular complex: The searchlight hypothesis. Proceedings of the National Academy of Sciences USA, 81, 4586-4590. Eriksen, C. W., & StJames, J. D. (1986). Visual attention within and around the field of focal attention: a zoom lens model. Perception and Psychophysics, 40, 225-240. Erlebacher, A., & Sekuler, R. (1974). Perceived length depends upon exposure duration: straight lines and Mtiller-Lyer stimuli. Journal of Experimental Psychology, 86, 202-207. Flavell, J. H., & Draguns, J. G. (1957). A microgenetic approach to perception and thought. Psychological Bulletin, 54, 197-217. Fr6hlich, W. D. (1984). Microgenesis as a functional approach to information processing through search. In W. D. Fr6hlich et al. (Eds.), Psychological processes in cognition and personality (pp. 19-52), Washington: Hemisphere. Goldberg, M. E., & Wurtz, R. H. (1972). Activity of superior collicuous in behaving monkey. 1-4. Journal of Neurophysiology, 35, 542-596. He, S., Cavanagh, P., & Intriligator, J. (1996). Attentional resolution and the locus of visual awareness. Nature, 383, 334-337. Holt-Hansen, K. (1975). Duration of experienced expansion and contraction of a circle.
Perceptual and Motor Skills, 41,507-518. Holt-Hansen, K. (1980). How does a figure appear and disappear in visual perception? Perceptual and Motor Skills, 50, 1327-1344. Howard, R. B. (1972). Complete assimilation of briefly presented lines. Canadian Journal of Psychology, 26, 259-267. Hughes, H. C., Fendrich, R., & Reuter-Lorenz, P. A. (1990). Global versus local processing in the absence of low spatial frequencies. Journal of Cognitive Neuroscience, 2, 272-282. Hughes, H. C., Nozawa, G., & Kitterle, F. (1996). Global precedence, spatial frequency channels, and the statistics of natural images. Journal of Cognitive Neuroscience, 8, 197230. Kimchi, R. (1992). Primacy of wholistic processing and global/local paradigm: A critical review. Psychological Bulletin, 112, 24-38. Klotz, W., & Wolff, P. (1995). The effect of a masked stimulus on the response to the masking stimulus. Psychological Research/Psychologische Forschung, 58, 92-101. LaBerge, D. (1995). Attentionalprocessing. Cambridge, MA: Harvard University Press. Lange, N. (1893). Psychological investigations. The law of perception and the theory of voluntary attention. Odessa: District Military Press. [in Russian] Nakatani, K. (1995). Microgenesis of the length perception of paired lines. Psychological Research/Psychologische Forschung, 58, 75-82. Navon, D. (1977). Forest before the trees: The precedence of global features in visual perception. Cognitive Psychology, 9, 353-383. Parker, D. M., Lishman, J. R., & Hughes, J. (1997). Evidence for the view that temporospatial integration in vision is temporally anisotropic. Perception, 26, 1169-1180. Sander, F. (1962). Experimentelle Ergebnisse der Gestaltpsychologie [Experimental results from gestalt psychology]. In F. Sander, & H. Volkelt (Eds.), Ganzheitspsychologie. Mu-
172 Talis Bachmann nich: Beck. [Reprinted from E. Becher (Ed.), 10. Kongressbericht Experimentelle Psycholo-
gic, 1928. Jena: Fischer] Sanocki, T. (1993). Time course of object identification: Evidence for a global-to-local contingency. Journal of Experimental Psychology: Human Perception and Performance, 19, 878-898. Scheibel, A. B. (1981). The problem of selective attention: a possible structural substrate. In O. Pompeiano & C. Ajmone Marsan (Eds.), Brain mechanisms and perceptual awareness, (pp. 319-326). New York: Raven. Scheibel, M. E., & Scheibel, A. B. (1967). Anatomical basis of attention mechanisms in vertebrate brains. In G. C. Quarton, T. Melnechuk, & F. O. P. Schmitt (Eds.), The neurosciences. A study program (pp. 577-602). New York: Rockefeller University Press. Scheibel, M. E., & Scheibel, A. B. (1970). Elementary processes in selected thalamic and cortical subsystems-- the structural substrates. In F. O. Schmitt (Ed.), The neurosciences. Second study program (pp. 443-457). New York: Rockefeller University Press. Sekuler, A. B., & Palmer, S. E. (1992). Perception of partly occluded objects: A microgenetic analysis. Journal of Experimental Psychology: General, 121, 95-111. Vekker, L. M. (1974). Mentalprocessesl Leningrad: University Press. [in Russian] Werner, H. (1957). The concept of development from a comparative and organismic point of view. In D. B. Harris (Ed.), The concept of development (pp. 125-148). Minneapolis: University of Minnesota Press. Wurtz, R. H., Goldberg, M. E., & Robinson, E. L. (1980). Behavioral modulation of visual responses in the monkey: stimulus selection for attention and movement. Progress in Psychobiology and Physiological Psychology, 9, 43-83.
About Neural Implementation and Microgenesis Commentary on Tsal
TalisBachmann Department of Psychology, University of Portsmouth, Un#ed Kingdom The main contribution of Tsal's paper consists in providing a strong and varied evidence for the facilitative effect of spatial selective attention on spatial discrimination. Another interesting empirical aspect relates to the finding that with unfocused spatial attention, the visual system creates certain perceptual illusions that are related to the poor spatial discrimination: overestimation of line length and the tendency to close small gaps within the extended visual objects. Tsal puts forward a theoretical construct to explain these effects - attentional receptive fields. Both the data reviewed and theory offered are highly valuable for the development of our understanding of visual cognition and advanced applied research in ergonomics. As follows, there will be few comments I would like to make with regard to the theoretical context Tsal's contribution might fit in.
1
Attentional Receptive Fields and Other Concepts of Spatial Attention
The conceptualisation put forward by Tsal is by no means the only one that relates selective attention to spatial resolution. One of the central notions of the zoom lens model by Eriksen (e.g., Eriksen & StJames, 1986) states that if attention is drawn to a spatial area, then its focus is initially large, but gradually "zooms in" at the designated region. Eriksen hypothesised that the larger the focus, the poorer the resolution within the focus and vice versa. Most of the data by Tsal is consistent with this theory. As a result of the putative zooming-in, spatial resolution increases and observers are better able to detect the gaps and localise the objects. The overestimation of size, however, becomes more difficult a problem for the zoom lens model. One would assume that observers would err in both directions with attention being spatially unfocused (or even tend to make more mistakes in the direction of underestimating the s i z e - the larger the focus, the relatively smaller the object may seem according to the contrast effect). In this respect, Tsal's model has an advantage over the zoom-lens model. In a recent study, Bachmann and Kahusk (1997) did find that precuing of spatially quantised target images caused different effects depending on the spatial scale of quantisation. Identification of the fine-quantised target images did not change much or was facilitated by attentional precuing. With coarse-quantised target images there
168 Talis Bachmann was a cost ofprecuing, however: preliminary focusing of attention had a detrimental effect on target identification. We explained this as a result of the effective spatialattentional routine, according to which attention gradually helps to activate perceptual representations, beginning with coarse levels of image description and proceeding on at the fine, detailed levels. The hypothesis of attentional receptive fields is not at odds with this. If precues cause attentional focusing that results in the activation of the fine-tuned (small) receptive fields, then what dominates perceptual representation at the moment when focusing is effected will be primarily the fine-scale image description. In case of coarse-quantised images, the fine scales carry only misleading information about pixel edges and corners, which explains the cost of precuing. This notion would require further development of Tsal's theory so as to involve the timecourse aspect of the activity of attentional receptive fields, however. In an important paper on the "crowding effect", He, Cavanagh, and Intriligator (1996) found that observers who were able to discriminate the small patches of variously oriented gratings if the patches were exposed in isolation, lost discrimination sensitivity if the same stimuli were presented among the spatially neighbouring, distractor, items. Importantly, single-cell recordings revealed that irrespective of the discrimination in explicit perceptual representation, visual cortical neurones that were tuned to the target stimuli kept responding in the same manner whether in "crowding" conditions or not. This is a piece of evidence proving that processing of the stimulus-specific information at the cortical level can be functionally independent of the attentive perception at the phenomenal level. This result is ambiguous with regard to the Tsal's theory. On the one hand, He et al.'s (1996) findings add credibility to Tsal's hypothesis by showing that not only the low-level visual receptive fields matter in phenomenal representation of spatial stimulus-information, but that some other (further?) processes related to parallel versus serial processing and/or limited capacity (attention?) should be important. On the other hand, the findings by He and his colleagues, by the virtue of showing precisely the neural equivalent for "preconscious" sensory discrimination, at the same time stress the lack of this kind of neurophysiological specificity in the Tsal's concept of attentional receptive fields. Computationally, the theory is apt. Neurophysiologically- unproven. Most of the existing neurophysiological evidence for the neural correlates of attentional processes seems to point towards the relatively poor spatial resolution of the neural systems that service spatial selective attention. For example, in the seminal works by Wurtz and his colleagues (e.g., Goldberg & Wurtz, 1972; Wurtz, Goldberg, & Robinson, 1980) superior colliculus' and cortical neurones have been found, the activity of what strongly correlates with covert orienting of spatial attention. These neurones, however, have receptive fields that are not as much finetuned as are the receptive fields of the neurones for perceptual stimulus representation proper. In several approaches nonspecific thalamic neurones have been described to fulfil the functions of focal attention (Scheibel, 1981; Scheibel & Scheibel, 1967, 1970; Crick, 1984; LaBerge, 1995; Bachmann, 1999). As a rule, the size of the receptive fields of the thalamic "orienting" and "awareness-related" neuronal systems is much larger than that of the specific, sensory-representational, system. All this contradicts the theory of attentional receptive fields which assumes just the opposite better spatial resolution for the attentional receptive fields in comparison with the
-
Commentary on Tsal 169 perceptual receptive fields without attentional involvement. How to solve this seeming contradiction? First, one might assume that Tsal will provide us with some direct neurophysiological evidence showing how the neurones which are the intimate part of some known attentional system evidence higher spatial discrimination power in comparison with the neurones of perceptual systems that are neuroanatomically independent of the attentional system. Second,- and this is my personal favouriteit may be more realistic to hope find that any anatomically distinct, exclusively attentional, neural system which has receptive fields with extremely good spatial resolution does not exist. What could happen instead is a spatial fine-tuning of the perceptual representational neurons under the effects of attention, with these neurons working much better in terms of spatial resolution if the nonspecific attentional modulation is applied. The neural structural correlate of the attentional receptive fields may not exist, but the functional correlate in terms of the interaction of the nonspecific attentional systems with the specific representational systems might be found. In my perceptual retouch conceptualisation (Bachmann, 1999) the positive effect of attention on the spatial resolution can be explained as follows. In order to guarantee good spatial resolution, the specific representational neurons should be active as a "full set". Most of the neurons that represent a perceptual object should be involved in building up or re-activating the representation. Involvement of attention facilitates nonspecific modulation of the activity of the specific representational neurons. As a result, the number of active neurons increases, and the signalto-noise ratio of the activity of the neurons that stand for the actually exposed object increases as well. The effect of overestimation of size could be the result of the prevalence of the activity of the neurons that mediate coarse levels of image description, given that attentional modulation has not been applied properly. 2
Microgenetic Perspective on Spatial Resolution and Size Estimation
It seems to me that Tsal's approach would benefit from the data and theoretical conceptions put forward from within the microgenetic approach to visual object perception in general and size estimation in particular. This approach assumes that percepts do not emerge instantly in their final form, but that percepts unfold in real time featuring several different, qualitatively distinct, stages (Lange, 1893; Sander, 1962; Werner, 1957; Flavell & Draguns, 1957; Vekker, 1974; Fr6hlich, 1984; Brown, 1988; Bachmann, 1977, 1991, 1998). Perhaps the most common findings have been that global (coarse) levels of perceptual object description precede the local (detailed, fine) levels of description (Navon, 1977; Bachmann, 1987; Kimchi, 1992; Sanocki, 1993; Parker, Lishman, & Hughes, 1997; Hughes, Fendrich, & Reuter-Lorenz, 1990; Hughes, Nozawa, & Kitterle 1996)and that the preceding, brief stimuli can influence the speed and qualitative aspects of the percept formation for the succeeding stimuli (Calis, Sterenborg, & Maarse, 1984; Bachmann, 1989; Klotz & Wolff, 1995; Sekuler & Palmer, 1992). Generally less known is the tradition to study the microgenesis of size perception. As Howard (1972), Erlebacher and Sekuler (1974), Holt-Hansen (1975, 1980), and Nakatani (1995)have demonstrated, the perceived size of a briefly presented stimulus is initially underestimated, but develops microgenetically over time.
170 Talis Bachmann At about 200 ms after the stimulus onset, the under-estimation may sometimes give place to over-estimation. It would be therefore useful if Tsal would consider both the effects of stimulus exposure duration and precue-to-target SOA on the results of his experiments. Only if these factors are systematically accounted for, one can be sure about the generality and validity of the results and their theoretical interpretations.
3
Conclusions
It seems that Tsal has suggested a potentially very useful concept, that of attentional receptive fields, that is consistent with a multitude of empirical facts about the attentional effects on spatial discrimination. The main elements of the theory (such as the location detectors and overlapping receptive fields with their strong computational potential) are consistent both with the empirical facts from the psychophysics of attention and standard requirements for cognitive architectures in the context of computational approaches. What remains to be done, however, is to show that and how these abstract concepts relate to the neurophysiological reality of perceptualattentional processing. Also, what stands behind the "assessment" of the activation levels of detectors in terms of the underlying neurophysiology? The main issue will undoubtedly be the distinction between the structural and functional varieties of the pending neuroreductionist explanation for attentional-perceptual (pertentional?) interaction. Even if the neurophysiological reality would contradict the notion of structurally distinct units that subserve fine-tuned attentional receptive fields, the concept suggested by Tsal can still be useful in the applied contexts. I am quite enthusiastic about the possibility to address also the question of perceptual microgenesis to show that the putative effects of the attentional receptive fields are not the artefactual outcomes of the variation in the microgenetic processes as a result of attentional manipulations. But then, maybe, microgenesis is the temporal dynamics of the employment of attentional receptive fields?
References Bachmann T. (1977). Contemporary psychophysics, phenomenology of experiment, and visual information processing. Acta et Commentationes Universitatis Tartuensis, #429, Studies in Psychology VI, 11-33. [in Russian] Bachmann, T. (1987). Different trends in perceptual pattern microgenesis as a function of the spatial range of local brightness averaging. Psychological Research, 49, 107-111. Bachmann, T. (1989). Microgenesis as traced by the transient paired-forms paradigm. Acta Psychologica, 70, 3-17. Bachmann T. (1991). Microgenesis in visual information processing: Some experimental results. In R. E. Hanlon (Ed.), Cognitive microgenesis. A neuropsychological perspective. (pp. 240-261). New York: Springer-Verlag. Bachmann, T. (1998). Is conscious experience established instantaneously? Commentary on Taylor. Consciousness and Cognition, 7, 149-156.
Commentary on Tsal 171 Bachmann, T. (1999). Twelve spatiotemporal phenomena and one explanation. In G. Aschersleben, T. Bachmann, & J. Mtisseler (Eds.), Cognitive contributions to the perception of spatial and temporal events. Amsterdam: Elsevier (this volume). Bachmann, T., & Kahusk, N. (1997). The effects of coarseness of quantisation, exposure duration, and selective spatial attention on the perception of spatially quantised ("blocked") visual images. Perception, 26, 1181-1196. Brown, J. (1988). The life of the mind. Hillsdale, NJ: Erlbaum. Calis, G., Sterenborg, J., & Maarse, F. (1984). Initial microgenetic steps in single-glance face recognition. Acta Psychologica, 55, 215-230. Crick, F. (1984). Function of the thalamic reticular complex: The searchlight hypothesis. Proceedings of the National Academy of Sciences USA, 81, 4586-4590. Eriksen, C. W., & StJames, J. D. (1986). Visual attention within and around the field of focal attention: a zoom lens model. Perception and Psychophysics, 40, 225-240. Erlebacher, A., & Sekuler, R. (1974). Perceived length depends upon exposure duration: straight lines and Mtiller-Lyer stimuli. Journal of Experimental Psychology, 86, 202-207. Flavell, J. H., & Draguns, J. G. (1957). A microgenetic approach to perception and thought. Psychological Bulletin, 54, 197-217. Fr6hlich, W. D. (1984). Microgenesis as a functional approach to information processing through search. In W. D. Fr6hlich et al. (Eds.), Psychological processes in cognition and personality (pp. 19-52), Washington: Hemisphere. Goldberg, M. E., & Wurtz, R. H. (1972). Activity of superior collicuous in behaving monkey. 1-4. Journal of Neurophysiology, 35, 542-596. He, S., Cavanagh, P., & Intriligator, J. (1996). Attentional resolution and the locus of visual awareness. Nature, 383, 334-337. Holt-Hansen, K. (1975). Duration of experienced expansion and contraction of a circle.
Perceptual and Motor Skills, 41,507-518. Holt-Hansen, K. (1980). How does a figure appear and disappear in visual perception? Perceptual and Motor Skills, 50, 1327-1344. Howard, R. B. (1972). Complete assimilation of briefly presented lines. Canadian Journal of Psychology, 26, 259-267. Hughes, H. C., Fendrich, R., & Reuter-Lorenz, P. A. (1990). Global versus local processing in the absence of low spatial frequencies. Journal of Cognitive Neuroscience, 2, 272-282. Hughes, H. C., Nozawa, G., & Kitterle, F. (1996). Global precedence, spatial frequency channels, and the statistics of natural images. Journal of Cognitive Neuroscience, 8, 197230. Kimchi, R. (1992). Primacy of wholistic processing and global/local paradigm: A critical review. Psychological Bulletin, 112, 24-38. Klotz, W., & Wolff, P. (1995). The effect of a masked stimulus on the response to the masking stimulus. Psychological Research/Psychologische Forschung, 58, 92-101. LaBerge, D. (1995). Attentionalprocessing. Cambridge, MA: Harvard University Press. Lange, N. (1893). Psychological investigations. The law of perception and the theory of voluntary attention. Odessa: District Military Press. [in Russian] Nakatani, K. (1995). Microgenesis of the length perception of paired lines. Psychological Research/Psychologische Forschung, 58, 75-82. Navon, D. (1977). Forest before the trees: The precedence of global features in visual perception. Cognitive Psychology, 9, 353-383. Parker, D. M., Lishman, J. R., & Hughes, J. (1997). Evidence for the view that temporospatial integration in vision is temporally anisotropic. Perception, 26, 1169-1180. Sander, F. (1962). Experimentelle Ergebnisse der Gestaltpsychologie [Experimental results from gestalt psychology]. In F. Sander, & H. Volkelt (Eds.), Ganzheitspsychologie. Mu-
172 Talis Bachmann nich: Beck. [Reprinted from E. Becher (Ed.), 10. Kongressbericht Experimentelle Psycholo-
gic, 1928. Jena: Fischer] Sanocki, T. (1993). Time course of object identification: Evidence for a global-to-local contingency. Journal of Experimental Psychology: Human Perception and Performance, 19, 878-898. Scheibel, A. B. (1981). The problem of selective attention: a possible structural substrate. In O. Pompeiano & C. Ajmone Marsan (Eds.), Brain mechanisms and perceptual awareness, (pp. 319-326). New York: Raven. Scheibel, M. E., & Scheibel, A. B. (1967). Anatomical basis of attention mechanisms in vertebrate brains. In G. C. Quarton, T. Melnechuk, & F. O. P. Schmitt (Eds.), The neurosciences. A study program (pp. 577-602). New York: Rockefeller University Press. Scheibel, M. E., & Scheibel, A. B. (1970). Elementary processes in selected thalamic and cortical subsystems-- the structural substrates. In F. O. Schmitt (Ed.), The neurosciences. Second study program (pp. 443-457). New York: Rockefeller University Press. Sekuler, A. B., & Palmer, S. E. (1992). Perception of partly occluded objects: A microgenetic analysis. Journal of Experimental Psychology: General, 121, 95-111. Vekker, L. M. (1974). Mentalprocessesl Leningrad: University Press. [in Russian] Werner, H. (1957). The concept of development from a comparative and organismic point of view. In D. B. Harris (Ed.), The concept of development (pp. 125-148). Minneapolis: University of Minnesota Press. Wurtz, R. H., Goldberg, M. E., & Robinson, E. L. (1980). Behavioral modulation of visual responses in the monkey: stimulus selection for attention and movement. Progress in Psychobiology and Physiological Psychology, 9, 43-83.