A componential model of human interaction with graphs: VI. Cognitive engineering of pie graphs.

This paper proposes and tests the following three-component model of reading a pie graph to estimate segment size: (a) selecting a mentally represented anchor segment (25%, 50%, or 75%), (b) mentally aligning representations of the anchor and target segments, and (c) mentally adjusting the size of the anchor to match the target. Experiment 1 showed that the size difference between the target and closest anchor and the angular displacement of the target from vertical predicted response times (RTs) and absolute error. Experiment 2 demonstrated that an aligned pie graph, designed to reduce the "align" portion of the process, produced faster RTs and lower error than did a regular pie graph. Experiment 3 showed that a pie graph labeled at the anchor values produced the same response times and absolute error as a regular pie graph but that a pie labeled off the anchor points produced a very different pattern of results. The discussion relates the results to the componential model and describes applications in increasing pie graph usability and developing design guidelines. Actual or potential applications of this research include guidelines for graph design and more usable pie graphs.

The effect of the Müller-Lyer illusion on map reading.

One important reason for studying visual illusions is that they can influence real-world perception as people interact with human-made displays. Three experiments examined how the Müller-Lyer illusion affects distance judgments and decision-making in the complex graphical context of a map by having subjects estimate the lengths of road segment lines framed by inward-going or outward-going wings in actual maps, in control displays that had the map context removed, and in simulated maps. The experiments showed that (1) outward-going wings led to higher distance estimates than did inward-going wings to the same extent both with and without the map context, (2) decisions based on distances determined from maps were affected by Müller-Lyer elements in the maps, and (3) map readers' measurement behavior influenced the effect of the Müller-Lyer elements in maps. The discussion focuses on how certain display manipulations and task manipulations affect the Müller-Lyer illusion. In addition, the discussion addresses the instances in which using a map might be affected by misestimation due to Müller-Lyer elements.

Visual arithmetic, computational graphics, and the spatial metaphor.

People who interact with graphs to perform arithmetic tasks typically employ quantitative features. However, they may employ the spatial metaphor under two alternative conditions: if they have been trained to apply visual arithmetic methods to traditional line and bar graphs, or if they interact with specially constructed and special-purpose computational graphics. Two experiments explored a visual arithmetic method used to train subjects to determine a mean by locating the spatial midpoint of a set of indicators (bars in a bar graph or points in a line graph). In Experiment 1 visual arithmetic subjects determined the mean of five indicators as quickly as they did the mean of two indicators; control subjects performed slower with five indicators. Both groups took more time to add the values of five indicators than to add two indicators. In Experiment 2, unlike control subjects, visual arithmetic subjects' response times in mean trials were unaffected by changes in the y-axis scale. However, both groups were affected by the y-axis scale on addition trials. Neither group was influenced by changes in the distance between indicators. The discussion addresses the transfer of visual arithmetic training to tasks that differ from the one used during training, uses for visual arithmetic and computational graphics, and the role of parallel processing and task restructuring in visual arithmetic.

A componential model of human interaction with graphs: 1. Linear regression modeling.

Task analyses served as the basis for developing the Mixed Arithmetic-Perceptual (MA-P) model, which proposes (1) that people interacting with common graphs to answer common questions apply a set of component processes--searching for indicators, encoding the value of indicators, performing arithmetic operations on the values, making spatial comparisons among the indicators, and responding; and (2) that the type of graph and user's task determine the combination and order of the components applied (i.e., the processing steps). Two experiments investigated the prediction that response time will be linearly related to the number of processing steps according to the MA-P model. Subjects used line graphs, scatter plots, and stacked bar graphs to answer comparison questions and questions requiring arithmetic calculations. A one-parameter version of the model (with equal weights for all components) and a two-parameter version (with different weights for arithmetic and nonarithmetic processes) accounted for 76%-85% of individual subjects' variance in response time and 61%-68% of the variance taken across all subjects. The discussion addresses possible modifications in the MA-P model, alternative models, and design implications from the MA-P model.

How should Fitts' Law be applied to human-computer interaction?

The paper challenges the notion that any Fitts' Law model can be applied generally to human-computer interaction, and proposes instead that applying Fitts' Law requires knowledge of the users' sequence of movements, direction of movement, and typical movement amplitudes as well as target sizes. Two experiments examined a text selection task with sequences of controlled movements (point-click and point-drag). For the point-click sequence, a Fitts' Law model that used the diagonal across the text object in the direction of pointing (rather than the horizontal extent of the text object) as the target size provided the best fit for the pointing time data, whereas for the point-drag sequence, a Fitts' Law model that used the vertical size of the text object as the target size gave the best fit. Dragging times were fitted well by Fitts' Law models that used either the vertical or horizontal size of the terminal character in the text object. Additional results of note were that pointing in the point-click sequence was consistently faster than in the point-drag sequence, and that pointing in either sequence was consistently faster than dragging. The discussion centres around the need to define task characteristics before applying Fitts' Law to an interface design or analysis, analyses of pointing and of dragging, and implications for interface design.

An analysis of the facilitative effect of similarity on second-order conditioning.

Five experiments used autoshaping in pigeons to investigate the effect of stimulus similarity on second-order conditioning of one stimulus (S2) when it signals another, previously conditioned stimulus (S1). Experiment 1 found that the artificial induction of similarity between S2 and S1, by the addition of experimentally separable common elements, improved performance during second-order conditioning of S2. An analysis of these results is given in terms of stimulus similarity encouraging the selection of particular components of S1 for association with S2. That selection is described as a natural consequence of the temporal relations among components of S2 and S1 which their similarity ensures. The analysis is used to generate circumstances under which the normal facilitative effect of similarity could be reversed once observed (Experiment 2A and 2B) or prevented from developing initially (Experiments 3 and 4). These experiments support a particular account of how a qualitative relation can affect the course of conditioning. However, that account requires the introduction of no special principles of conditioning unique to the case of similarity.

Increased drinking stimulated by exposure to lithium-conditioned taste cues: effects of conditioning trials and drug dose.

Rats first received differential conditioning in which the oral infusion of one flavored solution (the CS+) was followed by lithium injection and the oral infusion of a different solution (the CS-) was followed by no drug treatment. The intake of a novel palatable flavor was then measured after infusion exposure to either the lithium-conditioned CS+, the taste of tap water, or the CS-. Exposure to the CS+ stimulated more drinking than comparable exposure to tap water following 2-8 differential conditioning trials (Experiment 1), following conditioning with lithium doses of 0.75-3.0 mEq/kg (Experiment 2), and in comparison with both exposure to water and exposure to the CS- (Experiment 3). However, the phenomenon was not closely related to the degree of aversion subjects acquired to the lithium-paired taste solution. These results indicate that a complete characterization of the changes in drinking which are elicited by lithium-conditioned stimuli requires recognition of not only the suppression of intake commonly observed in the presence of the conditioned stimuli, but also the enhancement of intake evident as an after-effect of the lithium-conditioned stimuli.

Aftereffects of lithium-conditioned stimuli on consummatory behavior in the presence or absence of the drug.

Drinking is increased by prior exposure to lithium-conditioned stimuli. Experiment 1 showed that this phenomenon is not an artifact of testing subjects with a novel, palatable drinking fluid and also showed that lithium-conditioned olfactory stimuli produce a biphasic change in drinking, with drinking suppressed at the start of exposure to the conditioned stimulus (CS) and enhanced a long time after CS onset or exposure. Experiment 2 showed that the increased drinking aftereffect of lithium-conditioned stimuli is not a result of the instrumental reinforcement of the drinking response by the scheduling of water access following drug injections during conditioning, and Experiments 3, 4, and 5 showed that the increased drinking effect occurs even if subjects are injected with lithium prior to the test session. The results of Experiments 3 and 5 alos showed that lithium administration and exposure to lithium-conditioned stimuli have independent and opposite aftereffects: Lithium disrupts drinking, whereas prior exposure to lithium-conditioned stimuli increases consumption. The relevance of conditioned opponent and compensatory processes to the findings is discussed.

Effects of distribution of the drug unconditioned stimulus on taste-aversion learning.

Rats injected with lithium chloride after exposure to a taste or olfactory stimulus learn stronger aversions to these cues if the drug is administered in two small injections 35 min apart than if all of the drug is given in a single injection. This facilitation of conditioning produced by distribution of the drug unconditioned stimulus occurs with both low and high lithium doses (Experiments 1 and 2), is more evident in male than in female rats (Experiment 1), and is directly related to the amount of the flavored solution consumed prior to drug treatment (Experiment 4). Increasing the interval between two small drug injections beyond an optimal value results in a progressive loss of the facilitation of conditioning (Experiments 2 and 3), and the optimal drug distribution interval may be shorter for olfactory cues (Experiment 3) than for taste stimuli (Experiments 1 and 2). Control observations (Experiments 5A and 5B) showed that the drug distribution effect is not due to handling or other non-drug factors involved in giving two rather than only one injection. The phenomenon is consistent with recently-proposed models of conditioning and suggests that the differential effectiveness of various drugs in taste aversion conditioning may be related to differences in the time course of the unconditioned drug effects.

Learned suppression of ingestion: role of discriminative stimuli, ingestive responses, and aversive tastes.

Three experiments were designed to demonstrate that animals learn to suppress contact with aversive-tasting foods and fluids, and to investigate the behavioral mechanisms of this learning. In Experiment 1, domestic chicks (Gallus gallus) rapidly learned to suppress drinking during a visual stimulus (SQ) that signaled ingestion of a quinine solution but drank normally during a second visual stimulus (SW) that signaled water access. In Experiment 2, chicks in Group Con received oral infusions of quinine contingent upon drinking during SQ. Group Non received oral quinine infusions during SQ yoked to those of Group Con and noncontingent upon drinking. Only Group Con suppressed drinking during SQ. The third experiment investigated the contribution of the aversive taste and the postingestive effects into either the beak or the crop following drinking during SQ. Only the orally infused subjects suppressed drinking during SQ. These studies suggest that the relation between the drinking response and the aversive taste of quinine during SQ is crucial to the learned suppression of ingestion produced by the present procedures. The implications of these results for theories of food selection and Batesian mimicry are discussed.

Taste-aversion conditioning with expected versus unexpected drug treatment.

Following differential conditioning in which a drug-predictive taste solution (D) infused into the oral cavity of rats was followed by a lithium injection and a no-drug-predictive solution (ND) was not reinforced, animals received a backward pairing between lithium and a novel saccharin flavor. Subjects infused with either the D solution or tap water immediately before backward conditioning learned weaker saccharin aversions than animals infused with the ND solution and animals given no infusion at this time (Experiments 1 and 3). These latter groups did not differ from each other (Experiment 3). The interference with aversion learning produced by water infusion appeared to be due to conditioned excitation that accrued to sensations of the infusion process. Extinction of the infusion sensations eliminated blocking produced by the infusion of water (Experiments 4 and 5). The blocking of saccharin-aversion learning produced by infusion of the D solution was due, to a large extent, to the conditioned aversiveness of the D taste. Extinction of the aversion to the D taste eliminated the interference with saccharin conditioning (Experiment 2), whereas extinction of the excitatory properties of the infusion process did not prevent the blocking of conditioning by infusion of the D solution (Experiment 5). These results are inconsistent with suggestions that taste-aversion learning is a primitive form of conditioning; rather, they demonstrate the influence of informational variables on conditioned taste aversions.

Aftereffects of lithium-conditioned stimuli on consummatory behavior.

Exposure to taste or spatial cues previously paired with lithium administration resulted in more drinking during a test session started 15 min. later than did exposure to stimuli previously presented in the absence of drug treatment (Experiments 1, 2, 4, and 5). This outcome reflected an elevation of intake above baseline levels (Experiment 1) and required the presence of the lithium-paired cues rather than merely a history of lithium injections (Experiments 1, 2, 4, and 5). The increased drinking was evident in tests with novel (Experiments 1, 4, and 5) as well as familiar (Experiment 2) palatable solutions and was not attributable to a greater degree of thirst in subjects exposed to the lithium-predictive cues (Experiments 4 and 5). The phenomenon was attenuated by extinction of the lithium-conditioned stimuli (Experiment 3). However, the increased drinking aftereffect probably was not a result of the conditioned aversiveness of lithium-predictive cues, since shock-conditioned stimuli did not elicit enhanced consumption (Experiment 5). Various explanations of the effect are discussed.

Alteration by malignant transformation of the calcium requirements for cell proliferation in vitro.

Cells from the thigh muscles of normal fetal rats proliferated rapidly and indefinitely in a medium containing adult rat "plasma" and a normal free-calcium concentration, but they could not proliferate in calcium-deficient plasma medium. As the animals grew older, the cells became increasingly less able to proliferate even in normal (high-calcium) plasma medium, though they retained the potential to proliferate in a more conventional medium containing fetal bovine serum. By contrast, neoplastic adult cells from malignant rhabdomyosarcomas (induced by Ni3S2) proliferated rapidly and indefinitely in both normal and low-calcium plasma medium

Acetylcholine-induced initiation of thymic lymphoblast DNA synthesis and proliferation.

Low (5 times 10-9 M to 10-7 M) acetylcholine concentrations cause a calcium-independent stimulation of the initiation of DNA synthesis and proliferation of lymphoblasts which are part of rat thymocyte populations suspended in vitro. A much higher (5 times 10-5 M) acetylcholine concentration also stimulates lymphoblast DNA synthesis and proliferation, but this action is calcium-dependent. This proliferogenic response to acetylcholine is however not clearly mediated by either cyclic GMP or cyclic AMP.