Time and memory: towards a pacemaker-free theory of interval timing

A popular view of interval timing in animals is that it is driven by a discrete pacemaker-accumulator mechanism that yields a linear scale for encoded time. But these mechanisms are fundamentally at odds with the Weber law property of interval timing, and experiments that support linear encoded time can be interpreted in other ways. We argue that the dominant pacemaker-accumulator theory, scalar expectancy theory (SET), fails to explain some basic properties of operant behavior on interval-timing procedures and can only accommodate a number of discrepancies by modifications and elaborations that raise questions about the entire theory. We propose an alternative that is based on principles of memory dynamics derived from the multiple-time-scale (MTS) model of habituation. The MTS timing model can account for data from a wide variety of time-related experiments: proportional and Weber law temporal discrimination, transient as well as persistent effects of reinforcement omission and reinforcement magnitude, bisection, the discrimination of relative as well as absolute duration, and the choose-short effect and its analogue in number-discrimination experiments. Resemblances between timing and counting are an automatic consequence of the model. We also argue that the transient and persistent effects of drugs on time estimates can be interpreted as well within MTS theory as in SET. Recent real-time physiological data conform in surprising detail to the assumptions of the MTS habituation model. Comparisons between the two views suggest a number of novel experiments.     

Evaluation of quantitative theories of timing

Scalar timing theory is a clear, complete, modular, and precise theory of timing that explains much of the data from many timing procedures, but not all of the data from all of the procedures. The multiple-time-scale theory of timing provides an alternative representation of time that has not yet been tested with respect to its fit to timing data.     

Keep it local (and final): Remnant preferences in “let alone” ellipsis

The let alone construction (John can't run a mile, let alone a marathon) differs from standard coordination structures (with and or but) by requiring ellipsis of the second conjunct—for example, a marathon is the remnant of an elided clause [ John run a marathon]. In support of an ellipsis account, a corpus study of British and American English finds that let alone exhibits a Locality bias, as the second conjunct preferentially contrasts with the nearest lexical item of the same syntactic type. Two self-paced reading studies show that the Locality bias is active during online processing, but must be reconciled with indicators of semantic contrast and discourse information. Further, a sentence-rating study shows that the Locality bias interacts with a Finality bias that favours placing the let alone phrase at the end of a clause, which sometimes necessitates a nonlocal contrast. Together, the results show how a general bias in ellipsis for local contrasts is affected by discourse demands, such as the need for scalar contrast imposed by let alone, thereby offering a window into how possibly divergent syntactic and discourse constraints impact sentence processing.     

Mechanics of the animate.

Behavior is treated as basic physics. Dimensions are identified and their transformations from physical specification to axes in behavioral space are suggested. Responses are treated as action patterns arrayed along a continuum of activation energy. Behavior is seen as movement along a trajectory through this behavior space. Incentives or reinforcers are attractors in behavior space, at the centers of basins of lowered potential. Trajectories impinging on such basins may be captured; repeated capture will warp the trajectory toward a geodesic, a process called conditioning. Conditioning is enhanced by contiguity, the proximity between the measured behavior and the incentive at the end of the trajectory, and by contingency, the depth of the trajectory below the average level of the potential energy landscape. Motivation is seen as the potential of an organism for motion under the forces impinging on it. Degree of motivation is characterized by the depth of the potential field, with low motivation corresponding to a flat field and a flat gradient of activation energy. Drives are the forces of incentives propagated through behavior space. Different laws for the attenuation of drive with behavioral distance are discussed, as is the dynamics of action. The basic postulate of behavior mechanics is incentive-tracking in behavior space, the energy for which is provided by decreases in potential. The relation of temporal gradients to response differentiation and temporal discrimination is analyzed. Various two-body problems are sketched to illustrate the application of these ideas to association, choice, scalar timing, self-control, and freedom.     

THE BEHAVIORAL THEORY OF TIMING: TRANSITION ANALYSES

Gibbon and Church (1990, 1992) have recently confirmed an important, parameter-free prediction of the behavioral theory of timing (Killeen & Fetterman, 1988): The times of exiting from a bout of activity are positively correlated with the times of entrance to it. The correlations were slightly less than predicted, however, and the correlations between the start of an activity and the time spent engaged in that activity were negative, rather than zero. We adapted their serial model as an augmented (one-parameter) version of the behavioral theory, positing a lag between the receipt of a pulse from the pacemaker and transition into the next class of responses. The augmented version of the behavioral theory further improved the correspondence between the theory and the correlational data reported by Gibbon and Church. It also accounts for previously unpublished data from our laboratory derived from a new timing technique, the “peak choice” procedure. We show that the measured variance of movement times from one key to another closely approximates the estimated variance of transition times recovered from fits of the augmented model to the data. Such correspondence both attests to the correct identification of this source of variance and suggests ways to remove it, both from behavior and from our models of behavior.     

键盘时间精度的一个图示法研究

以4个实验,用图示法对键盘的时间精度作了比较分析。实验1表明PES心理实验系统反应键和键盘都有良好的时间精度。实验2表明键盘的时间精度具有很大的个体差异,范围从1-2毫秒到40多毫秒,其中PS2的键盘普遍不理想。实验3表明键盘的时间精度不受转接器和计算机主频的影响。实验4使用了3名操作者,证实了这种方法的效果基本不受操作者个体差异的影响。研究演示了图示法在计算机控制的心理学实验中确定仪器的时间精度的作用,提示了实验中需要针对具体的实验条件判断时间精度是否符合实验要求,来确定是否选用特殊的反应键或者选择何种键盘作为反应的方式。     

A Turing Test for Computational and Associative Theories of Learning

A Turing test is proposed to evaluate current computational and associative models of learning, and to guide theoretical developments. This test requires a specification of the procedures to which the model applies, a sampling of procedures and response measures, and an objective way to determine the difficulty of discriminating the responses of the model from the responses of the animal. Scalar timing theory is used as an example of a well-developed computational theory of timing that involves addition, multiplication, division, and sampling. The behavioral theory of timing is used as an example of a well-developed associative theory of timing that involves state transitions and strengthening of connections. A Turing test provides a way to evaluate such theories.     

时距知觉中的情绪效应

情绪极易影响时距知觉,致使主观时距偏离客观时距。新近研究者们结合日趋成熟的标量计时模型及神经学相关依据,并通过采用标准化情绪诱发材料的实验研究,较为系统地解释了情绪的生理唤醒和注意唤醒两种成分各自对内部计时机制造成的干扰效应。研究发现,两种效应中前者会加长主观时距而后者会使其缩短,且分别有不同的发生特点。该文在介绍国内外关于时距知觉中的情绪效应的新近研究基础上,提出应从探索两种效应的分离方法、考虑记忆效应因素以及增加实验自变量的数目和取值水平三个方面来开展进一步的研究     

时距估计中的重复刺激效应

Treisman及其同事最早发现人类对时距的判断很容易受到重复刺激的影响而发生扭曲或偏离,并认为时距估计中的重复刺激具有两种效应。着重介绍了时距估计中重复刺激效应产生的机制及其理论模型、重复刺激效应的影响因素。提出了时距估计中重复刺激效应未来研究中值得关注的几个主要问题。     

标量计时模型中的神经机制

标量计时模型中各阶段的神经机制有重叠也有分离。从当今认知神经科学的研究结果看,与内部时钟有关的神经结构有小脑、基底神经节、前额皮质、前运动辅助皮质及顶叶下回皮质等;与记忆阶段有关的神经结构有基底神经节、背外侧前额皮质、右侧额下皮质及外侧前运动皮质等;与决策阶段有关的神经结构有背外侧前额皮质、前扣带回、高级颞叶皮质和基底神经节等。文章还从神经机制角度论证了计时的标量特性,讨论了今后研究值得注意的三个问题,即研究结果的确定性、研究手段的局限性以及该模型的适用性