Time and Mind II: Information Processing Perspectives

Revue canadienne de psychologie experimentale, 2005, 59-2, 139-142 Canadian Journal of Experimental Psychology, 2005, 59-2, 139-142 Reviewed by Scott W. Brown, University of Southern Maine Time Is Everywhere: Review of H. Helfrich, (Ed.), Time and Mind II: Information Processing Perspectives Time has been a topic of intense interest to psychologists from the very beginnings of the field, and it continues to be the focus of much experimental and theoretical work. The reason for this continued interest is that time is everywhere in the psychological landscape. Temporal phenomena represent a core element of virtually all psychological processes. All behaviour, from the macro level of actions, perceptions, and thoughts, to the micro level of brain function, neurological networks, and responses of individual neurons, occurs in time. These processes have their own temporal dynamics, they operate on their own time scales, and they affect the timing of other processes and mechanisms. This wide-ranging character of time has drawn the attention of many different specialists, and Helfrich's book represents a sampling of some of these perspectives. The book is based on the symposium "Time and Mind 02," held at the University of Hildesheim in September 2002. The contributions represent a mixed format, ranging from straight experimental reports to literature reviews to descriptions of elaborate theoretical models. The 12 chapters are divided evenly into two parts, "Time as an Object of Information Processing" and "Time as a Constituent of Information Processing." Part 1: Time as an Object of Information Processing Researchers in time perception probably will find the first part of the book to be of greater interest and relevance. The first three chapters relate to the Scalar Expectancy Theory of timing. Scalar Expectancy Theory (SET), originally derived from the animal timing literature, describes a multicomponent timing model involving a biologically driven pacemaker-accumulator mechanism, a memory component, and a decision-making component. Chapter 1 ("Simultaneous Temporal Processing" by Russell M. Church, Paulo Guilhardi, Richard Keen, Mika MacInnis, & Kimberly Kirkpatrick) consists of a review of the work on simultaneous timing in laboratory animals. The authors describe the segmented fixed-interval procedure, in which the fixed interval includes stimulus events that serve to subdivide the interval into smaller parts. Although the procedure has been used to test hypotheses related to the chaining of responses and secondary reinforcers, its major impact is that "the fixed-interval procedure makes it clear that they (animals) are able to time two intervals simultaneously" (p. 12). The authors argue that simultaneous timing is also evident in numerous conditioning procedures, including Pavlovian delay and trace conditioning, and in the effects of variations in trial and intertrial intervals. They suggest that modifications to SET, such as incorporating another set of independent pacemaker-memory-decision components, may be required to account for the results. However, human research on multiple timing (not discussed by Church et al.) may require more substantial changes to SET than those envisioned here. Indeed, researchers in recent years have adapted some of the standard animal research paradigms used to test SET in an effort to evaluate the theory in terms of human timing. In Chapter 2 "Applying the Scalar Timing Model to Human Time Psychology: Progress and Challenges," John H. Wearden provides a well-organized review of this work. Wearden points out that the theory faces certain challenges when applied to human timing, especially the memory and decision components of the model. Other compatibility issues arise with the shift from animal to human experimentation, including the role of attention in timing and the implementation of different time judgment methodologies. One of the chief benefits of the application of SET to human studies, in Wearden's view, is that it brings back the emphasis of an internal timer/clock mechanism to human timing. Richard A. Block's contribution (Chapter 3, "Psychological Timing Without a Timer: The Roles of Attention and Memory") is a good companion piece to Wearden's paper. Block's review of SET highlights numerous problems with the model as it applies to the world of human timing. An especially serious problem (also acknowledged by Wearden) is that SET does not address the role of attention, yet attention is the primary focus of much of the contemporary work on human timing. Block also describes how some basic assumptions and methodological differences between the animal and human research traditions limit the integration of this work. Both SET and Block's own Attentional Gate model are pacemaker/clock-based notions, and here Block argues for an alternative "timer-without-atimer" memory-based model that may be able to account for a wider range of temporal phenomena. The theme of the next two chapters (by Simon Grondin and Florian Klapproth, respectively) is timing psychophysics. Grondin (Chapter 4, "Sensory Modalities and Temporal Processing") provides a detailed review of duration discrimination studies, with special reference to the influence of the auditory and visual events that mark the endpoints of intervals. Empty intervals demarcated by visual-auditory or auditory- visual events exert systematic "intermodal" effects, such that intervals marked by the V-A sequence are perceived as shorter than those marked by the A-V sequence. Another factor influencing timing performance is the length of the markers, with longer markers impairing temporal discrimination. The data also show that auditory events are usually judged to be longer than visual events. Grondin concludes that a pacemaker/clock model offers only a limited account for these effects, and that such a model must incorporate cognitive factors to enhance its explanatory power. Klapproth (Chapter 5, "Notable Results Regarding Temporal Memory and Modality") describes three experiments on temporal generalization in the visual and auditory modes. This research shows that subjects make discriminations that are more accurate when the training and testing stimuli are in the same sensory modality. When the training and testing modalities are different, however, subjects tend to underestimate the test intervals. Can Scalar Timing account for the data? Klapproth argues yes, that the results reflect differences in the pulse accumulation process. The argument is that switching to a different modality delays the accumulation of pulses. The accumulation process is delayed because crossmodal conditions slow the activation of the reference duration stored in memory. The first part of the book concludes with Chapter 6 "Sensory and Cognitive Mechanisms in Temporal Processing Elucidated by a Model System Approach," a review paper written by Thomas Rammsayer. Rammsayer surveys the results of 15 years of psychopharmacological experiments conducted in his laboratory. Subjects in these experiments perform duration discrimination tasks while taking drugs that affect various neurotransmitter systems. The findings suggest that there may be two timing systems, one dedicated to processing intervals in the seconds range, and the other designed to process short durations (less than 500 ms). The longer-duration system operates under cognitive control, and is influenced by attentional allocation and working memory processes. The shorter-duration system is more sensory driven, automatic, and reflects the activity of subcortical structures. Rammsayer proposes that the two timing systems may not be completely independent, and that each may influence the functioning of the other. Part 2: Time as a Constituent of Information Processing Part 2 of the book expands the topic of timing beyond perception, and considers the importance of temporal phenomena in neural processing, sensory integration, and brain function. The dominant theme is the temporal organization of neurophysiological processes. In Chapter 7 "Temporal Characteristics of Auditory Event-Synthesis: Electrophysiological Studies," Istvan Czigler, Istvan Winkler, Elyse Sussmann, Hirooki Yabe, and Janos Horvath review studies of the Mismatch Negativity (MMN) component of event-related potentials. MMNs occur in response to unusual or unexpected auditory events (e.g., infrequent tones occurring within a stream of frequent tones). MMNs do not require attention (subjects typically read books, play video games, or perform demanding tasks while being exposed to the auditory stimuli), and thus represent an automatic process of change detection. The results of various MMN studies show that auditory input streams are integrated into 200 ms chunks. Czigler et al. conclude that although preattentive processes are not emphasized in most timing models, such processes may have an influence in temporal perception (see also the description of the Rammsayer paper above). The next two chapters focus on the temporal characteristics of visual processing. In Chapter 8 "Exploring the Timing of Human Visual Processing," Simo Vanni, Michel Dojat, Jan Warnking, Christoph Segebarth, and Jean Bullier offer a detailed, technical article concerning some of the problems involved in analyzing the timing and locations of responses in the brain to visual stimuli. The authors show that visual stimuli produce widespread activation of complex cortical networks, which complicates an analysis of the timing and distribution of these events. In addition, the presence of noise, crosstalk, and artifacts impose limits on spatial and temporal resolution. Measurement methodology also represents another hurdle for researchers. The chapter includes an interesting discussion of the strengths and weaknesses of the fMRI, EEG, and MEG techniques, and describes how different time scales are associated with the neural responses registered by these methods. Andreas K. Engel (Chapter 9, "Time and Conscious Visual Processing") delivers a well-presented review of the problem of how the brain integrates sensory inputs over time, and how these cortical binding processes result in conscious experience. The focus of the review is on visual awareness. Although colour, form, and motion are processed in parallel in different networks, these neural responses are integrated by the brain to form a coherent representation in conscious awareness. Engel discusses the physiological evidence for the notion of temporal binding - the idea that neurons responding to an object fire impulses in temporal synchrony. Such synchrony would selectively tag neural responses for the same object. In essence, neural synchrony provides an "additional coding dimension" (p. 156) that complements the conventional code based on firing rate. The author asserts that not only does neural synchrony establish coherent sensory representations, but it also contributes to the formation of consciousness. Chapters 10 and 11 are more strictly theoretical. The paper by Robert B. Glassman (Chapter 10, "Hypothesized Temporal and Spatial Code Properties for a Moment's Working Memory Capacity: Brain Wave 'Harmonies' and 'Four-Color' Topology of Activated Cortical Areas") is primarily an essay, rather than a review of data. The topic is how underlying neural processes give rise to working memory (WM). Glassman argues that the most commonly accepted WM capacity limit of 7+/-2 items is too large, and that "during briefer moments, working memory capacity for simultaneous, vivid apprehension of a number of items is not as great as seven but is really only about three or four" (p. 162). This core capacity of 3-4 items constitutes an immediate cognitive present, a "narrow doorway" through which information enters the cognitive system. The author proposes that three or four EEG frequencies could code the three or four items held in active WM at any given moment. Glassman points out that the WM core limit of three or four items may also be related to certain mathematical properties associated with topology and graph theory. He expands on this idea by suggesting that the cortex may be viewed as a thin, essentially two-dimensional, sheet of tissue that is divided into functional regions ("patches") of activation. Each patch may be subdivided into "subpatches," corresponding to WM chunks of information. Chapter 11 "Invariants in Mental Timing: From Taxonomic Relations to Task-Related Modeling," by Hans-Georg Geissler and Raul Kompas, consists of an introduction to Geissler's Taxonomic Quantum Model (TQM). Basically, TQM proposes that cognitive processing is organized into discrete periods, which are multiples of approximately 4.5 ms. This value of 4.5 ms is considered by the authors to be the smallest quantal period. A review of data across different domains (including psychophysical measurements of the absolute threshold for hearing, critical thresholds in motion perception, periodicities in reaction time distributions, and duration discrimination performance) reveals the existence of numerical invariants based on quantal periods. Of particular interest to time psychologists is that Geissler and Kompass envision a timing system comprising multiple oscillators operating with different temporal resolutions, which form a hierarchy of critical periods. Standard clock models that postulate one central pacemaker mechanism of necessity require additional components to account for various specifics of the situation, whereas the multiple oscillator structure represents a more general-purpose timing system that can accommodate different circumstances. The volume concludes with Chapter 12 "Behavioral and Electrophysiological Oscillations in Information Processing: A Tentative Synthesis," written by Boris Burle, Francoise Macar, and Michel Bonnet. Burle et al. provide a cogent review of behavioural and neurophysiological oscillations in information processing. This review covers the issue of discontinuity in perception, motor behaviour, and reaction time, all of which reveal periodicities in information processing (see also the description of the chapter by Geissler and Kompass above). Based on the literature, the authors outline a temporal oscillator model, in which an internal oscillator mechanism chunks information and paces the receptivity of the neurons receiving the information. In this scheme, the incoming flow of environmental information is coded into "packets" and transmitted to the next stage of processing. An important feature of the model is the "dual pacing hypothesis," in which the temporal oscillator also excites neurons to receive the packets. Cortical noise is minimized by being distributed equally between neural receptive and nonreceptive (i.e., inhibited) states, thus ensuring that cortical signals are reliably transmitted and received. This packaging- and-pacing process is believed to operate under conditions of mental workload or attentional constraint. The authors conclude that "oscillation is not necessary to information processing, it is simply useful, especially when working under time pressure, or when the task is intrinsically difficult" (p. 226). As with any edited volume, the book has certain limitations and strengths. The coverage of material in some chapters overlaps that in others, the chapters vary in length and style, and there is the impression that some chapters are only peripherally related to the gener...