Melissa J. Allman

Pathophysiological distortions in time perception and timed performance

Distortions in time perception and timed performance are presented by a number of different neurological and psychiatric conditions (e.g. Parkinsons disease, schizophrenia, attention deficit hyperactivity disorder and autism). As a consequence, the primary focus of this review is on factors that define or produce systematic changes in the attention, clock, memory and decision stages of temporal processing as originally defined by Scalar Expectancy Theory. These findings are used to evaluate the Striatal Beat Frequency Theory, which is a neurobiological model of interval timing based upon the coincidence detection of oscillatory processes in corticostriatal circuits that can be mapped onto the stages of information processing proposed by Scalar Timing Theory.

Properties of the Internal Clock: First- and Second-Order Principles of Subjective Time

Humans share with other animals an ability to measure the passage of physical time and subjectively experience a sense of time passing. Subjective time has hallmark qualities, akin to other senses, which can be accounted for by formal, psychological, and neurobiological models of the internal clock. These include first-order principles, such as changes in clock speed and how temporal memories are stored, and second-order principles, including timescale invariance, multisensory integration, rhythmical structure, and attentional time-sharing. Within these principles there are both typical individual differences--influences of emotionality, thought speed, and psychoactive drugs--and atypical differences in individuals affected with certain clinical disorders (e.g., autism, Parkinsons disease, and schizophrenia). This review summarizes recent behavioral and neurobiological findings and provides a theoretical framework for considering how changes in the properties of the internal clock impact time perception and other psychological domains.

Developmental neuroscience of time and number: implications for autism and other neurodevelopmental disabilities.

Estimations of time and number share many similarities in both non-humans and man. The primary focus of this review is on the development of time and number sense across infancy and childhood, and neuropsychological findings as they relate to time and number discrimination in infants and adults. Discussion of these findings is couched within a mode-control model of timing and counting which assumes time and number share a common magnitude representation system. A basic sense of time and number likely serves as the foundation for advanced numerical and temporal competence, and aspects of higher cognition—this will be discussed as it relates to typical childhood, and certain developmental disorders, including autism spectrum disorder. Directions for future research in the developmental neuroscience of time and number (NEUTIN) will also be highlighted.

Learning processes affecting human decision making: An assessment of reinforcer-selective pavlovian-to-instrumental transfer following reinforcer devaluation

In reinforcer-selective transfer, Pavlovian stimuli that are predictive of specific outcomes bias performance toward responses associated with those outcomes. Although this phenomenon has been extensively examined in rodents, recent assessments have extended to humans. Using a stock market paradigm adults were trained to associate particular symbols and responses with particular currencies. During the first test, individuals showed a preference for responding on actions associated with the same outcome as that predicted by the presented stimulus (i.e., a reinforcer-selective transfer effect). In the second test of the experiment, one of the currencies was devalued. We found it notable that this served to reduce responses to those stimuli associated with the devalued currency. This finding is in contrast to that typically observed in rodent studies, and suggests that participants in this task represented the sensory features that differentiate the reinforcers and their value during reinforcer-selective transfer. These results are discussed in terms of implications for understanding associative learning processes in humans and the ability of reward-paired cues to direct adaptive and maladaptive behavior.

ON THE CORRESPONDENCE BETWEEN PREFERENCE ASSESSMENT OUTCOMES AND PROGRESSIVE-RATIO SCHEDULE ASSESSMENTS OF STIMULUS VALUE

The current study examined whether stimuli of different preference levels would be associated with different amounts of work maintained by the stimuli, as determined through progressive-ratio schedule break points. Using a paired-choice preference assessment, stimuli were classified as high, moderate, or low preference for 4 individuals with developmental disabilities. The stimuli were then tested three times each using a progressive-ratio schedule (step size of 1; the break-point criterion was 1 min). In 10 of 12 possible comparisons, higher preference stimuli produced larger break points than did lower preference stimuli.

Deficits in temporal processing associated with autistic disorder

Currently idiopathic autism is typically diagnosed according to an observational assessment of certain behavioral, social, and cognitive tendencies across dimensions of language, social interaction, imaginative play, and restricted or repetitive cognitions and behavior. Parent interview is required to confirm presence of specific tendencies within the first 3 years of life. There is, as yet, no bio-medical test or marker for autism, although certain neurological, genetic, and physiological differences are known. There are often common co-morbid disorders, such as problems with sleep, motor function and attention-hyperactivity. An individual is diagnosed along spectrum of impairment (autistic disorder or autism spectrum disorder). Thus any psychological theory of autism is required to describe differences, and similarities, across a range of behavioral, social and cognitive abilities, within and between affected individuals. Arguably the three most dominant theories of autistic disorder relate to weak central coherence (or information processing), executive functioning, and theory of mind. There may be another hitherto, rather unacknowledged possibility: a deficit in temporal processing. An adaptive sensitivity to the duration of events, and time between them, is critical to adaptive cognitive, behavioral, and social function. There are anecdotal and clinical reports of problems with time in autistic disorder, and successful applied behavioral educational and therapeutic supports with this population often include external signals to indicate the passage of time, temporal structure, and upcoming events. Currently, the empirical literature on temporal processing in autistic disorder is relatively scant, and encompasses findings spanning a range of psychology; neurological, genetic, behavioral, and cognitive, observational, and computational assessments. These include reports that children with autism experience difficulties imaging past and future changes of a current situation and understanding that successive events are part of a unitary process; differences in temporal reproduction and duration perception (in the interval range); and electrophysiological reports of disordered temporal binding of stimulus input, apparently over extended periods (than is typical). These findings are usually complementary, although vary greatly in the nature of the methods and analysis used (for a review, see Allman and Meck, 2011). There is preliminary evidence from data modeling to suggest that aspects of the perception of duration might be “developmentally delayed” in this population (see Allman et al., 2011). Consistent among these aforementioned findings is the interpretation of results within the context of a deficit in (some aspect of) temporal processing in autistic disorder (e.g., Boucher et al., 2007). These range from suppositions that affected individuals experience problems thinking about time and higher temporal cognition, to notions that there are fundamental differences in the quality of the “subjective present” as it relates to the temporal processing of sensory information. Clock gene anomalies have been related to sleep, memory, and timing problems in autistic disorder. There have been several attempts to assert a hypothesis of temporal processing disturbance in autistic disorder, both within the discussion of published reports, or in more speculative accounts which go so far as to describe diagnostic features of autistic disorder as manifestations of atypical aspects of temporal processing (for details, see Allman and DeLeon, 2009). However, there is as yet, no well-defined profile of temporal processing abilities in these individuals, and no sufficiently specified theory. Perhaps the appeal of a temporal deficit hypothesis of autism might be its ability to assimilate the traditional, and well supported accounts of autism into one, encompassing and testable hypothesis. It might also be possible to account for diagnostic features of the disorder. For instance, atypical social synchrony and temporal patterning may reduce the quality of social bonding, joint attention, and the to- and fro of social reciprocity, and communication (the latter are heavily implicated in autism). Differences in the ability to integrate sensory inputs and events over time may create problems with perception, learning and memory, and create problems of weak central coherence. Deficits in temporal processing might influence and be related to known differences in patterns of local and global information processing (couched within information-processing traditions), and executive functions (e.g., episodic memory, planning). Pathological restricted and repetitive behaviors and interests, rituals and routines, might otherwise have adaptive significance, such that they serve to parse or regulate temporal processing and compensate for a failure to predict events, and reduce posited disorientation in time. The relative length and complexity of rituals or routines has previously been posited to correspond to the extent (boundary) of temporal thought in affected individuals. Assuming that sensitivity to duration is related to our subjective sense of time, then autistic problems with imaginative play, empathizing, and theory of mind might be otherwise considered related to deficits in aspects of temporal processing – being able to export oneself into the mind of another person likely requires some form of “mental time travel.” It is important to stress that to-date the study of temporal processing in autism is in its infancy, however a temporal deficit hypothesis of autistic disorder does not appear premature given the relevant literature. At a more general level, there is little doubt that increased knowledge of temporal processing in autism is both necessary and likely fruitful both for the scientist, and the affected individual who has the potential to benefit from improved social and non social temporal supports. Collectively, there are reasonable, and promising grounds to support a hypothesis of autism based on deficits in temporal processing.

Examination of the influence of contingency on changes in reinforcer value.

This study examined how the amount of effort required to produce a reinforcer influenced subsequent preference for, and strength of, that reinforcer in 7 individuals with intellectual disabilities. Preference assessments identified four moderately preferred stimuli for each participant, and progressive-ratio (PR) analyses indexed reinforcer strength. Stimuli were then assigned to one of four conditions for 4 weeks: fixed-ratio (FR) 1 schedule, escalating FR schedule, yoked noncontingent (NCR) delivery, and restricted access. Preference assessments and PR schedules were then repeated to examine changes in selection percentages and PR break points. Selection percentages decreased for all NCR stimuli but increased for most of the restricted stimuli. There were no systematic changes in selection percentages for either of the contingent stimuli. Break points increased, on average, for all conditions, but the increase was highest for the restricted stimuli and lowest for the NCR stimuli. These results are discussed in relation to recent basic research addressing the influence of effort on stimulus value.

Transfer of configural learning between the components of a preexposed stimulus compound: implications for elemental and configural models of learning.

In 2 experiments, rats received preexposure to 2 compound contexts: AB and CD for the congruent group and AC and BD for the incongruent group. Subsequently, all rats received a configural discrimination in which separate placement in contexts A or B indicated that presentations of stimulus X would be followed by food and presentations of Y would not, and separate placement in contexts C and D indicated that Y would be followed by food and X would not. In both experiments, rats in the congruent group acquired the conditional discrimination more rapidly than those in the incongruent group. These results are inconsistent with conventional associative accounts of either stimulus preexposure effects or configural learning and instead provide support for a connectionist account.

A brief history of "The Psychology of Time Perception"

Basic mechanisms of interval timing and associative learning are shared by many animal species, and develop quickly in early life, particularly across infancy, and childhood. Indeed, John Wearden in his book “ The Psychology of Time Perception ”, which is based on decades of his own research with colleagues, and which our commentary serves to primarily review, has been instrumental in implementing animal models and methods in children and adults, and has revealed important similarities (and differences) between human timing (and that of animals) when considered within the context of scalar timing theory. These seminal studies provide a firm foundation upon which the contemporary multifaceted field of timing and time perception has since advanced. The contents of the book are arguably one piece of a larger puzzle, and as Wearden cautions, “The reader is warned that my own contribution to the field has been exaggerated here, but if you are not interested in your own work, why would anyone else be?” Surely there will be many interested readers, however the book is noticeably lacking in it neurobiological perspective. The mind (however it is conceived) needs a brain (even if behaviorists tend to say “the brain behaves”, and most neuroscientists currently have a tenuous grasp on the neural mechanisms of temporal cognition), and to truly understand the psychology of time, brain and behavior must go hand in hand regardless of the twists, turns, and detours along the way.

Associative change in connectionist networks: an addendum.

The results of a recent study have provided direct support for the suggestion that conditional learning in rats is best characterized by a 3-layer connectionist network (M. J. Allman, J. Ward-Robinson, & R. C. Honey, 2004). In the 2 experiments reported here, rats were used to investigate the nature of the changes that occur when a stimulus compound is presented, whose components activate hidden units associated with food and no food, and either food or no food is presented. The results of both experiments, while controlling for the possible contribution of associations between these hidden units (within-layer links), provide evidence that the distribution of associative change between units in the hidden layer that are activated by the stimulus compound and those in the output layer (between-layer links) are unequal. They also indicate that associative change is more marked on trials on which no food was presented than on trials on which food was presented.