Temporal structure coding with and without awareness

In order to interpret a constantly changing environment, visual events far apart in space and time must be integrated into a unified percept. While spatial properties of invisible signals are known to be encoded without awareness, the fate of temporal properties remains largely unknown. Here, we probed temporal integration for two distinct motion stimuli that were either visible or rendered invisible using continuous flash suppression. We found that when invisible, both the direction of apparent motion and the gender of point-light walkers were processed only when defined across short time periods (i.e., respectively 100 ms and 1000 ms). This limitation was not observed under full visibility. These similar findings at two different hierarchical levels of processing suggest that temporal integration windows shrink in the absence of perceptual awareness. We discuss this phenomenon as a key prediction of the global neuronal workspace and the information integration theories of consciousness.     

Learned prediction affects body perception

Learning to recognize objects appears to depend critically on extended observation of appearance over time. Specifically, temporal association between dissimilar views of an object has been proposed as a tool for learning invariant representations for recognition. We examined heretofore untested aspects of the temporal association hypothesis using a familiar dynamic object, the human body. Specifically, we examined the role of appearance prediction (temporal asymmetry) in temporal association. In our task, observers performed a change detection task using upright and inverted images of a walking body either with or without previous exposure to a motion stimulus depicting an upright walker. Observers who were exposed to the dynamic stimulus were further divided into two groups dependent on whether the observed motion depicted forward or backward walking. We find that the effect of the motion stimulus on sensitivity is highly dependent on whether the observed motion is consistent with past experience.     

Learning influences the encoding of static and dynamic faces and their recognition across different spatial frequencies

Studies on face recognition have shown that observers are faster and more accurate at recognizing faces learned from dynamic sequences than those learned from static snapshots. Here, we investigated whether different learning procedures mediate the advantage for dynamic faces across different spatial frequencies. Observers learned two faces—one dynamic and one static—either in depth (Experiment 1) or using a more superficial learning procedure (Experiment 2). They had to search for the target faces in a subsequent visual search task. We used high-spatial frequency (HSF) and low-spatial frequency (LSF) filtered static faces during visual search to investigate whether the behavioural difference is based on encoding of different visual information for dynamically and statically learned faces. Such encoding differences may mediate the recognition of target faces in different spatial frequencies, as HSF may mediate featural face processing whereas LSF mediates configural processing. Our results show that the nature of the learning procedure alters how observers encode dynamic and static faces, and how they recognize those learned faces across different spatial frequencies. That is, these results point to a flexible usage of spatial frequencies tuned to the recognition task.     

Perception of motion affects language processing

Recently developed accounts of language comprehension propose that sentences are understood by constructing a perceptual simulation of the events being described. These simulations involve the re-activation of patterns of brain activation that were formed during the comprehender's interaction with the world. In two experiments we explored the specificity of the processing mechanisms required to construct simulations during language comprehension. Participants listened to (and made judgments on) sentences that described motion in a particular direction (e.g. "The car approached you"). They simultaneously viewed dynamic black-and-white stimuli that produced the perception of movement in the same direction as the action specified in the sentence (i.e. towards you) or in the opposite direction as the action specified in the sentence (i.e. away from you). Responses were faster to sentences presented concurrently with a visual stimulus depicting motion in the opposite direction as the action described in the sentence. This suggests that the processing mechanisms recruited to construct simulations during language comprehension are also used during visual perception, and that these mechanisms can be quite specific.     

Unsignaled delay of reinforcement, relative time, and resistance to change

Two experiments with pigeons examined the effects of unsignaled, nonresetting delays of reinforcement on responding maintained by different reinforcement rates. In Experiment 1, 3-s unsignaled delays were introduced into each component of a multiple variable-interval (VI) 15-s VI 90-s VI 540-s schedule. When considered as a proportion of the preceding immediate reinforcement baseline, responding was decreased similarly for the three multiple-schedule components in both the first six and last six sessions of exposure to the delay. In addition, the relation between response rates and reinforcement rates was altered such that both parameters of the single-response version of the matching law (i.e., k and Re) were decreased. Experiment 2 examined the effects of unsignaled delays ranging from 0.5 s to 8.0 s on responding maintained by a multiple VI 20-s VI 120-s schedule of reinforcement. Response rates in both components increased with brief unsignaled delays and decreased with longer delays. As in Experiment 1, response rates as a proportion of baseline were affected similarly for the two components in both the first six and last six sessions of exposure to the delay. Unlike delays imposed between two stimulus events, the effects of delays between responses and reinforcers do not appear to be attenuated when the average time between reinforcers is longer. In addition, the disruptions produced by unsignaled delays appear to be inconsistent with the general finding that responding maintained by higher rates of reinforcement is less resistant to change.     

Examining the between- and within-person effects of relative deprivation: Results from a 7-year longitudinal panel sample

Despite the extensive literature on relative deprivation theory, few studies have examined the longitudinal effects of individual- and group-based relative deprivation (IRD and GRD, respectively) on individual- and group-based outcomes, nor has research investigated the between-person and within-person effects of these constructs. Using two random intercept cross-lagged panel models, we address these oversights by estimating the between-person and average annual within-person associations IRD and GRD have with psychological distress and collective action support in a nation-wide longitudinal panel sample (N = 64,607). As expected, IRD and GRD were more strongly associated with psychological distress and collective action support, respectively, at the between-person level and contemporaneously at the within-person level. However, contrary to expectations, temporary departures in IRD and GRD predicted within-person increases in collective action support and psychological distress, respectively. These results raise questions about how and when people respond to inequality and provide the foundations for future longitudinal research.     

Oral self-administration of pentobarbital by rhesus monkeys: relative reinforcing effects under concurrent fixed-ratio schedules.

During daily 3-hr sessions, orally delivered pentobarbital solutions and water, or two separate pentobarbital solutions, were concurrently available to rhesus monkeys according to fixed-ratio schedules of mouth contacts with a spout. First water, and then each of four "comparison-concentration" pentobarbital solutions (0.0625, 0.25, 1, and 4 mg/mL), was successively available from one spout for a block of sessions under a fixed-ratio-64 (three monkeys) or fixed-ratio-16 (one monkey) schedule. Under an identically sized fixed-ratio schedule, deliveries of a "standard-concentration" pentobarbital solution were concurrently available from a second spout. The concentration of the standard solution remained unchanged throughout testing of the series of comparison solutions. Each of three pentobarbital concentrations (4, 1, and 0.25 mg/mL) in turn served as the standard concentration. Within each pair of concurrently available solutions, the higher drug concentration maintained more behavior than the lower concentration. Thus when monkeys were provided with concurrent access to different pentobarbital concentrations, relative reinforcing effects were directly related to drug concentration. Further, the amount of behavior maintained by a particular drug concentration was dependent on the concentration of the concurrently available drug solution. Thus, the relative effectiveness of a reinforcer in maintaining behavior is a function of both the reinforcer's magnitude and the availability of alternative reinforcers in the environment.     

儿童运动行距预测能力的发展及影响因素

采用计算机软件控制实验,以三种不同运动速度、四种不同运动行距组合呈现的光点运动为刺激物,每次光点在暴露运动一段行程后进入遮蔽,要求儿童判断光点到达目标位置时按键反应。主要结果表明：（１）儿童运动行距预测能力的发展表现为５─８岁和１２─１９岁两个加速期及８─１２岁一个过渡期的发展模式。但在过渡期内,儿童的预测误差偏向有显著变化;（２）客体运动速度对儿童运动行距预测操作精度有显著影响,慢速下精度较高;（３）客体运动行距、被试性别并不影响儿童的行距预测操作;（４）５岁、１２岁与１９岁儿童多倾向于超前反应。     

恒河猴对50以下数目的估计

本研究有６个从易到难的程序,每个程序有标准数目和比较数目,都是白卡片上的黑圆点。每次试验先呈现标准数目作为样本,强化后撤去,随后同时呈现标准数目和比较数目,令动物作二择一反应。实验结果表明,影响恒河猴数目估计的有两个主要因素,即标准数目和比较数目之间的数间距和这两个数目本身的大小。在数间距为４或大于４时,恒河猴能对５０以下的数作出估计;在数间距为２时,恒河猴能对９－２５的数作出估计,但不能对２７－４９的数作估计。作者以为,这里所进行的是一种相对的区域性的数目估计,但它仍然是一种数标签的过程。