Simultaneous temporal and spatial processing

Rats searched for food that was contingent on time and place in an open field. One location was active at a time, the active location moved in a clockwise direction after each reward, and each location was repeated several times on each daily session. When a location was active, the first response after a fixed interval produced food. The intervals associated with each of the four locations were consistently 60, 30, 30 and 60 sec. For independent groups, inspecting an inactive location had no consequence (n = 7) or reduced the amount of food delivered at the active location (n = 6). The rates of inspecting active and inactive locations increased before the associated intervals elapsed, with preferential responding at the active locations. Rates of anticipation at active locations failed to superimpose when plotted as a function of proportional time. Simultaneous temporal and spatial processing contributed to the failure of proportional timing.     

Dynamic averaging and foraging decisions in horses (Equus callabus)

The variability of most environments taxes foraging decisions by increasing the uncertainty of the information available. One solution to the problem is to use dynamic averaging, as do some granivores and carnivores. Arguably, the same strategy could be useful for grazing herbivores, even though their food renews and is more homogeneously distributed. Horses (Equus callabus) were given choices between variable patches after short or long delays. When patch information was current, horses returned to the patch that was recently best, whereas those without current information matched choices to the long-term average values of the patches. These results demonstrate that a grazing species uses dynamic averaging and indicate that, like granivores and carnivores, they can use temporal weighting to optimize foraging decisions.     

Children's and adults' judgments of equitable resource distributions

This study explored the criteria that children and adults use when evaluating the niceness of a character who is distributing resources. Four- and five-year-olds played the 'Giving Game', in which two puppets with different amounts of chips each gave some portion of these chips to the children. Adults played an analogous task that mimicked the situations presented to children in the Giving Game. For all groups of participants, we manipulated the absolute amount and proportion of chips given away. We found that children and adults used different cues to establish which puppet was nicer: 4-year-olds focused exclusively on absolute amount, 5-year-olds showed some sensitivity to proportion, and adults focused exclusively on proportion. These results are discussed in light of their implications for equity theory and for theories of the development of social evaluation.     

Gaze step distributions reflect fixations and saccades: a comment on

In three experimental tasks Stephen and Mirman (2010) measured gaze steps, the distance in pixels between gaze positions on successive samples from an eyetracker. They argued that the distribution of gaze steps is best fit by the lognormal distribution, and based on this analysis they concluded that interactive cognitive processes underlie eye movement control in these tasks. The present comment argues that the gaze step distribution is predictable based on the fact that the eyes alternate between a fixation state in which gaze is steady and a saccade state in which gaze position changes rapidly. By fitting a simple mixture model to Stephen and Mirman's gaze step data we reveal a fixation distribution and a saccade distribution. This mixture model captures the shape of the gaze step distribution in detail, unlike the lognormal model, and provides a better quantitative fit to the data. We conclude that the gaze step distribution does not directly suggest processing interaction, and we emphasize some important limits on the utility of fitting theoretical distributions to data.     

Concurrent learning of temporal and spatial sequences

In a serial reaction time task, stimulus events simultaneously defined spatial and temporal sequences. Responses were based on the spatial dimension. The temporal sequence was incidental to the task, defined by the response-to-stimulus intervals in Experiment 1 and stimulus onset asynchronies in Experiment 2. The two sequences were either of equal length and correlated or of unequal length. In both experiments, spatial learning occurred regardless of sequence length condition. In contrast, temporal learning occurred only in the correlated condition. These results suggest that timing is an integrated part of action representations and that incidental learning for a temporal pattern does not occur independently from the action. Interestingly, sequence learning was enhanced in the correlated condition, reflecting the integration of spatial-temporal information.     

A neural network model of foraging decisions made under predation risk

This article develops the cognitive—emotional forager (CEF) model, a novel application of a neural network to dynamical processes in foraging behavior. The CEF is based on a neural network known as the gated dipole, introduced by Grossberg, which is capable of representing short-term affective reactions in a manner similar to Solomon and Corbit’s (1974) opponent process theory. The model incorporates a trade-off between approach toward food and avoidance of predation under varying levels of motivation induced by hunger. The results of simulations in a simple patch selection paradigm, using a lifetime fitness criterion for comparison, indicate that the CEF model is capable of nearly optimal foraging and outperforms a run-of-luck rule-of-thumb model. Models such as the one presented here can illuminate the underlying cognitive and motivational components of animal decision making.     

Body- and environmental-stabilized processing of spatial knowledge

In 5 experiments, the authors examined the perceptual and cognitive processes used to track the locations of objects during locomotion. Participants learned locations of 9 objects on the outer part of a turntable from a single viewpoint while standing in the middle of the turntable. They subsequently pointed to objects while facing the learning heading and a new heading, using imagined headings that corresponded to their current actual body heading and the other actual heading. Participants in 4 experiments were asked to imagine that the objects moved with them as they turned and were shown or only told that the objects would move with them; in Experiment 5, participants were shown that objects could move with them but were asked to ignore this as they turned. Results showed that participants tracked object locations as though the objects moved with them when shown but not when told about the consequences of their locomotion. Once activated, this processing mode could not be suppressed by instructions. Results indicated that people process object locations in a body- or an environment-stabilized manner during locomotion, depending on the perceptual consequences of locomotion.     

On the interdependence of temporal and spatial judgments

Three experiments are reported on the tau and kappa effects, the dependence of judgments of distance upon duration (tau) and of judgments of duration upon distance (kappa). In Experiment 1, three lights in a horizontal sequence were used to define two temporal and two spatial intervals over a total duration of 160 msec. The subject was required to choose the shorter of either the two durations or the two distances. The results confirmed Collyer’s (1977) findings that the two effects are inconsistently observed across subjects when the display duration is brief. In Experiment 2, display duration was systematically manipulated from 160 to 1,500 msec. It is argued that relative temporal judgments should become easier as the total display duration is increased and that, hence, the kappa effect should become less marked. On the other hand, relative spatial judgments should become more difficult as the total duration of the display is increased, and the tau effect should become more marked. The data were in conformity with the hypothesis. In Experiment 3, data are presented for a tau experiment which fit the assumption that the effect depends upon a weighted average of distance and the expected distance which would be traversed in the given time at constant velocity.     

The effects of spatial frequency and temporal waveform on three measures of temporal processing

The effects of spatial frequency and temporal transition of sine-wave grating onset and offset were assessed using measures of reaction time, visual persistence, and temporal order judgements. The stimuli were lateralized fields, separated by 1 degree of visual angle. Slow temporal transition resulted in significantly poorer performance than did abrupt onset and offset, but spatial frequency had a minimal effect. Thus, the latency, temporal resolution, and temporal ordering of events are mediated by a mechanism that is sensitive to abrupt temporal transients. The stimulus conditions employed did not result in a shift in the point of subjective simultaneity.     

Vibrotactile masking: Some spatial and temporal aspects

Threshold elevations (TE) were determined for three Os at a test site on the left thigh with a masker placed singly at each of 10 widespread loei on the trunk. Although lateral changes in masker placement did not produce a significant alteration in TE (p> .10), there was a systematic decrease in TE with longitudinal separation between masker and test sites on the body. Appropriate manipulations of the time interval between masker and test signals were found effective in offsetting these decreases. It appeared that longitudinal separations were differentially affecting temporal delays by producing unequal neural distances from the test and masker sites to the CNS. There were, however, some spatial changes that could not be accounted for by temporal offsets. Thresholds at a finger test site were significantly less elevated (p< .01) by contralateral placement of maskers than by ipsilateral placement, and the particular test site chosen for threshold determinations, either index finger or thigh, determined the amount of TE.     

The spatial and temporal signatures of word production components

This paper presents the results of a comprehensive meta-analysis of the relevant imaging literature on word production (82 experiments). In addition to the spatial overlap of activated regions, we also analyzed the available data on the time course of activations. The analysis specified regions and time windows of activation for the core processes of word production: lexical selection, phonological code retrieval, syllabification, and phonetic/articulatory preparation. A comparison of the word production results with studies on auditory word/non-word perception and reading showed that the time course of activations in word production is, on the whole, compatible with the temporal constraints that perception processes impose on the production processes they affect in picture/word interference paradigms.     

Modeling spatial and temporal aspects of visual backward masking

Visual backward masking is a versatile tool for understanding principles and limitations of visual information processing in the human brain. However, the mechanisms underlying masking are still poorly understood. In the current contribution, the authors show that a structurally simple mathematical model can explain many spatial and temporal effects in visual masking, such as spatial layout effects on pattern masking and B-type masking. Specifically, the authors show that lateral excitation and inhibition on different length scales, in combination with the typical time scales, are capable of producing a rich, dynamic behavior that explains this multitude of masking phenomena in a single, biophysically motivated model.     

Role of spatial and temporal coincidence in depth organization

The linking of spatial information is essential for coherent space perception. A study is reported of the contribution of temporal and spatial alignment for the linkage of spatial elements in terms of depth perception. Stereo half-images were generated on the left and right halves of a large-screen video monitor and viewed through a mirror stereoscope. The half-images portrayed a black vertically oriented bar with two brackets immediately flanking this bar and placed in crossed or uncrossed disparity relative to the bar. A pair of thin white 'bridging lines' could appear on the black bar, always at zero disparity. Brackets and bridging lines could be flickered either in phase or out of phase. Observers judged whether the brackets appeared in front of or behind the black bar, with disparity varied. Compared to conditions when the bridging lines were absent, depth judgments were markedly biased toward "in front" when bridging lines and brackets flashed in temporal phase; this bias was much reduced when the bridging lines and brackets flashed out of phase. This biasing effect also depended on spatial offset of lines and brackets. However, perception was uninfluenced by the lateral separation between object and brackets.     

Human sensitivity to temporal proximity: The role of spatial and temporal speed gradients

Estimates of temporal proximity (sometimes called time-to-collision) from random-dot flow patterns are shown to be based upon retinal speed, rather than upon changes in dot density. Neither the spatial nor the temporal gradient of motion is essential to the task, but estimates can be made from either alone. Performance is unaffected by the addition of rotational motion, suggesting that observers axe capable of extracting the radial component of motion, which contains all the relevant information, from complex stimuli.     

How decisions evolve: The temporal dynamics of action selection

To study the process of decision-making under conflict, researchers typically analyze response latency and accuracy. However, these tools provide little evidence regarding how the resolution of conflict unfolds over time. Here, we analyzed the trajectories of mouse movements while participants performed a continuous version of a spatial conflict task (the Simon task). We applied a novel combination of multiple regression analysis and distribution analysis to determine how conflict on the present trial and carry-over from the previous trial affect responding. Response on the previous trial and the degree of conflict on the previous and the current trial all influenced performance, but they did so differently: The previous response influenced the early part of the mouse trajectory, but the degree of previous and current conflict influenced later parts. This suggests that in this task experiencing conflict may not proactively ready the system to handle conflict on the next trial; rather, when conflict is experienced on the subsequent trial the previous compensatory processing may be re-activated more efficiently.     

Organization of visuo-spatial serial memory: interaction of temporal order with spatial and temporal grouping

This study investigates whether memory for sequences of spatial locations can be represented hierarchically, that is, as successive groups containing the order of constituent locations. Two grouping manipulations are used: Temporal grouping, based on the verbal serial memory literature, and spatial grouping, based on recent empirical work on visuo-spatial serial memory. In Experiment 1, we examine the relationship between spatial grouping and temporal order and showed that recall performance increases when both temporal and spatial organization correlate, but decreases when they clash. Experiments 2 and 3 show that the latter result is confounded by differences in path length (length of spatial path defined by the locations) between conditions, and that no effect of the spatial organization is observed when path length is controlled for. In Experiment 4, an alternative method to spatial grouping, temporal grouping, is used to induce hierarchical organization. A recall advantage is found in the temporal grouping condition. The results suggest that hierarchical representations can be imposed on order information for visuo-spatial sequences, either when participants have pre-existing knowledge about the form of the path formed by the sequence or when temporal boundaries delimit chunks; that increased path length is the cause of the performance decrement observed when dots from separate spatial groups are presented successively; and that path length and more generally sequence characteristics should be taken into account in designing future research on visuo-spatial serial memory.     

The effects of prior expectations and outcome knowledge on polygraph examiners' decisions

The present study deals with the question of whether judgments made by experts working in familiar contexts are affected by prior expectations and beliefs. Two experiments in which prior expectations were manipulated were designed to determine whether and to what extent polygraph examiners are affected by their prior expectations when analyzing and interpreting polygraph charts. Prior expectations affected the examiners' judgments when the polygraph charts did not include clear indications of guilt or innocence, but when the objective physiological evidence included strong indications which clearly contradicted the examiner's expectations, judgments were not affected by these expectations. Theoretical and practical implications of these results are discussed.