Language,duration estimation,and causation

Burt (2002) raises several interesting points in his commentary on our paper. However, the most important difference between his and our studies, the design, was not addressed. We argue that our experimental approach makes more realistic assumptions for causal interpretation. The other points that he raises—the relationship between practical and statistical significance, the verbs used by our participants, and definitions of memory—are all discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

Choice, foraging, and reinforcer duration.

Pigeons were exposed to a foraging schedule characterized by three different states, beginning with a search state in which completion of a variable interval on a white key led to a choice state. In the choice state the subject could, by appropriate responding on a fixed ratio of three, either accept or reject the schedule offered. If the subject accepted the schedule, it entered a handling state in which the appropriate reinforcer amount was presented according to a variable-interval schedule. In Experiment 1 the shorter duration reinforcer was more likely to be accepted the longer the duration of the search state and the shorter the equal durations of the handling states. In Experiment 2 the shorter duration reinforcer was more likely to be accepted the longer the handling time preceding the longer duration reinforcer. All of the results were in qualitative--and some were in quantitative--agreement with those predicted by the delay-reduction hypothesis and the optimal-diet model.     

Scaling subjective velocity,distance, and duration

By magnitude estimation, the relation between the subjective and physical values of linear velocities, durations, and distances were found to be power functions with exponents of about 0.75, 0.90, and 0.90. When subjective values are substituted for their physical correlates in the equation, velocity = distance/duration, we obtain:

$$subjective velocity = k(\tfrac{{subjective distance}}{{subjective duration}})0.8$$     

Ethnicity, sleep duration, and sleep satisfaction

Analysis of responses of 1100 students from four ethnic groups to questions about the quantity and quality of their sleep indicated that ethnicity was modestly but significantly related.     

Stimulus familiarity,dogmatism, and the duration of attention

Thirtyeight males and 30 females viewed each of 30 black and white photographs for as long as they wished. Half the photographs were judged by the Es to be unfamiliar to college students. The remaining photographs were judged to be familiar. After the looking task all Ss cotnpleted the Dogmatism Scale. It was predicted that the open-minded Ss would spend more time looking at the novel stimuli than the closed-minded Ss, and, that all Ss would spend more time looking at novel stimuli than familiar stimuli. The results failed to confirm the hypothesis that open-minded Ss would look longer at the novel stimuli than closed-minded Ss. However, it was found that Ss spent more time looking at novel stimuli than familiar stimuli regardless of the degree to which their belief systems were opened or closed. The adwwtage of manipulating stimulus familiarity by E-selection of the stimuli was discussed.     

Perceived duration,visual persistence,and neural integration

Varying stimulus intensity while measuring the perceived duration/visual persistence of brief light flashes has yielded disparate results. Some studies have found a direct relationship between the two variables; others have found an inverse relationship. Several models have been suggested to unify this behavioral literature. They invoke the absolute intensity and the nature of the judgment as explanatory variables. We now present physiological data whose analysis was motivated by these models. We measured the duration of photoreceptor potentials as a function of light intensity and response measure. One response measure was. the length of time required for the response to decline from the peak by a criterion amount. The other response measure was the length of time a response stayed above a criterion level. These data suggest that each behaviorally based model captured a different aspect of a single underlying mechanism and that a melding of the two critical concepts would harmonize all of the results: In this melding, the sensory signals that mediate visual perception would have the type of complex intensity- and time-dependent properties found in real neural responses.     

Contrast, component duration, and the following schedule of reinforcement

Experiment 1 investigated component duration in a four-component multiple schedule designed to separate the effects of the preceding schedule of reinforcement from those of the following schedule of reinforcement. The preceding schedule in the preceding component had no consistent effect regardless of component duration. The following schedule was a powerful determinant of behavior, however, with higher response rates resulting from a following period of extinction. Moreover, the effect of the following schedule was greater with short component durations, which strongly suggests that component-duration effects previously found with multiple schedules are due generally to variation in the degree of control by the following schedule. Experiments 2--4 investigated the basis of the effects of the following schedule. In some situations differential responding in the following component was the controlling variable, but in others it was differential reinforcement in the following component. The results are consistent with the view that response rate during a stimulus is inversely related to the "value" of the following component, where the calculation of value must include both primary and conditioned reinforcement.     

Choice, relative reinforcer duration, and the changeover ratio

Relative reinforcer duration was varied in concurrent schedules with a fixed-ratio four changeover requirement. The schedule in effect after each reinforcer was randomly chosen. For all three pigeons, relative response rates overmatched relative reinforcer durations. Time allocation was less extreme and, on the average, matched relative reinforcer duration. In a subsequent manipulation, the level of preference was shown to depend on the size of the changeover requirement. These results are similar to those from related unequal reinforcement-frequency procedures.     

Leaving patches: effects of economy, deprivation, and session duration

Three pigeons pecked keys for food reinforcers in a laboratory analogue of foraging in patches. Half the patches contained food (were prey patches). In prey patches, pecks to one key occasionally produced a reinforcer, followed by a fixed travel time and then the start of a new patch. Pecks to another key were exit responses, and immediately produced travel time and then a new patch. Travel time was varied from 0.25 to 16 s at each of three session durations: 1, 4, and 23.5 hr. This part of the experiment arranged a closed economy, in that the only source of food was reinforcers obtained in prey patches. In another part, food deprivation was manipulated by varying postsession feeding so as to maintain the subjects' body weights at percentages ranging from 85% to 95% of their ad lib weights, in 1-hr sessions with a travel time of 12 s. This was an open economy. Patch residence time, defined as the time between the start of a patch and an exit response, increased with increasing travel time, and consistently exceeded times predicted by an optimal foraging model, supporting previously published results. However, residence times also increased with increasing session duration and, in longer sessions, consistently exceeded previously reported residence times in comparable open-economy conditions. Residence times were not systematically affected by deprivation levels. In sum, the results show that the long residence times obtained in long closed-economy sessions should probably be attributed to session duration rather than to economy or deprivation. This conclusion is hard to reconcile with previous interpretations of longer-than-optimal residence times but is consistent with, in economic terms, a predicted shift in consumption towards a preferred commodity when income is increased.     

Maximizing,choice freedom,and duration judgments in choice making

This paper examines (a) whether people are less accurate in judging choice time as choice tasks involve more choice options, more choice information, or a combination of both and (b) whether people with a higher tendency to look for the best option in choice making (maximizers) have less accurate duration judgments of choice time as compared to people who are more easily settling for a choice outcome that is satisfactory (satisficers). A multilevel analysis is used to explore the relationships of interest using data collected through a series of choice tasks. In general, the results suggest that people seem to misjudge time durations when making choices. Moreover, empirical evidence demonstrates that people with an outspoken tendency to maximize in choice making do not differ significantly in estimating choice time accurately as compared to people who experience almost no need to maximize.     

Attention, exposure duration, and gaze shifting in naming performance

Two experiments are reported in which the role of attribute exposure duration in naming performance was examined by tracking eye movements. Participants were presented with color-word Stroop stimuli and left- or right-pointing arrows on different sides of a computer screen. They named the color attribute and shifted their gaze to the arrow to manually indicate its direction. The color attribute (Experiment 1) or the complete color-word stimulus (Experiment 2) was removed from the screen 100 ms after stimulus onset. Compared with presentation until trial offset, removing the color attribute diminished Stroop interference, as well as facilitation effects in color naming latencies, whereas removing the complete stimulus diminished interference only. Attribute and stimulus removal reduced the latency of gaze shifting, which suggests decreased rather than increased attentional demand. These results provide evidence that limiting exposure duration contributes to attribute naming performance by diminishing the extent to which irrelevant attributes are processed, which reduces attentional demand.     

Visual masking effects on duration,size, and form discrimination

In duration, size, and form discrimination tasks, a visual noise mask was presented at variable delays after stimulus offset in order to interrupt processing and control the extent of processing time. Previous work (Thomas & Cantor, 1975) had suggested that both perceived duration and perceived nontemporal “information” might be expected to increase as processing time was extended. As predicted, accuracy in the discrimination of size of circles and form of non-sense figures was found to vary directly with stimulus duration (20, 50 msec) and mask delay interval (0, 30, 70, 110 msec). Differences in perceived duration between filled (forms or circles) and unfilled (blank) intervals were found to increase monotonically with increases in the mask delay interval, when non-sense forms, but not circles, were presented. Two hypotheses of visual masking (“integration” and “interruption”) are discussed. Within the context of the “integration” hypothesis, a model is proposed which predicts processing time as a function of stimulus duration, mask delay interval, and the interval between onset of the mask and termination of processing.     

Display polarity, stimulus exposure duration, and visual lobe shape

This study investigated the effects of visual display polarity and stimulus exposure duration on visual lobe shape. Analysis showed that regardless of display polarity and exposure duration combinations tested here, visual lobe contours were slightly irregular and asymmetric, of medium roundness, with a moderately rough boundary, and horizontally elongated with a mean length-width ratio of 1.53. Visual lobes mapped with negative display polarity were significantly rounder, slightly more regular and more symmetric along the vertical axis, compared with those mapped with positive polarity. Under the different polarity conditions, there were no significant differences in visual lobe area, perimeter, boundary smoothness, and elongation. When stimulus exposure duration increased from 200 to 400 msec. and from 200 to 300 msec., there were significant increases in the visual lobe area, perimeter, roundness, boundary smoothness, and regularity. No such changes were found when duration increased from 300 to 400 msec. Exposure durations did not have a significant effect on the shape categories of elongation and horizontal symmetry for the different stimuli. There were no statistically significant interactions between polarity and stimulus exposure duration for any of the lobe shape indexes used here.