Diana Kornbrot

Haptic virtual reality for blind computer users

This paper describes a series of studies involving a haptic device which can display virtual textures and 3-D objects. The device has potential for simulating real world objects and assisting in the navigation of virtual environments. Three experiments investigated: (a) whether previous results from experiments using real textures could be replicated using virtual textures; (b) whether participants perceived virtual objects to have the intended size and angle; and (c) whether simulated real objects could be recognised. In all the experiments differences in perception by blind and sighted people were also explored. The results have implications for the future design of VEs in that it cannot be assumed that virtual textures and objects will feel to the user as the designer intends. However, they do show that a haptic interface has considerable potential for blind computer users.

Depressive Realism and Outcome Density Bias in Contingency Judgments: The Effect of the Context and Intertrial Interval

The perception of the effectiveness of instrumental actions is influenced by depressed mood. Depressive realism (DR) is the claim that depressed people are particularly accurate in evaluating instrumentality. In two experiments, the authors tested the DR hypothesis using an action-outcome contingency judgment task. DR effects were a function of intertrial interval length and outcome density, suggesting that depressed mood is accompanied by reduced contextual processing rather than increased judgment accuracy. The DR effect was observed only when participants were exposed to extended periods in which no actions or outcomes occurred. This implies that DR may result from an impairment in contextual processing rather than accurate but negative expectations. Therefore, DR is consistent with a cognitive distortion view of depression.

Differential effects of age on prospective and retrospective memory tasks in young, young-old, and old-old adults

Remembering to do something in the future (termed prospective memory) is distinguished from remembering information from the past (retrospective memory). Because prospective memory requires strong self-initiation, Craik (1986) predicted that age decrements should be larger in prospective than retrospective memory tasks. The aim of the present study was to assess Craiks prediction by examining the onset of age decline in two retrospective and three prospective memory tasks in the samples of young (18–30 years), young-old (61–70 years), and old-old (71–80 years) participants recruited from the local community. Results showed that although the magnitude of age effects varied across the laboratory prospective memory tasks, they were smaller than age effects in a simple three-item free recall task. Moreover, while reliable age decrements in both retrospective memory tasks of recognition and free recall were already present in the young-old group, in laboratory tasks of prospective memory they were mostly present in the old-old group only. In addition, older participants were more likely to report a retrospective than prospective memory failure as their most recent memory lapse, while the opposite pattern was present in young participants. Taken together, these findings highlight the theoretical importance of distinguishing effects of ageing on prospective and retrospective memory, and support and extend the results of a recent meta-analysis by Henry, MacLeod, Phillips, and Crawford (2004).

Signal detection theory, the approach of choice : model-based and distribution-free measures and evaluation

New and old methods of analyzing two-choice experiments with confidence ratings are evaluated. These include the theory of signal detectability (TSD), Luces choice theory,nonparametric techniques based on areas under receiver-operating characteristic (ROC) functions, and methods based onS′ and Ω, proposed by Balakrishnan and his colleagues. New methods for assessing the bias of a complete ROC function are proposed, together with an additional area-based measure of response bias. Area measures of both sensitivity and bias proved the most consistent. Response bias for a full ROC function was larger than bias at the cut point and also provided additional information. Participants showed voluntary control of bias for all measures except Ω. Unequal variance versions of TSD and choice models gave similar fits to data, with the choice model closer to an equal variance version. Discrimination data from Balakrishnan (1999) formed the empirical test bed.

Creative mathematics : do SAT-M sex effects matter?

Copyright Cambridge University Press [Full text of this article is not available in the UHRA]

Applying software metrics to formal specifications: a cognitive approach

It is generally accepted that failure to reason correctly during the early stages of software development causes developers to make incorrect decisions which can lead to the introduction of faults or anomalies in systems. Most key development decisions are usually made at the early system specification stage of a software project and developers do not receive feedback on their accuracy until near its completion. Software metrics are generally aimed at the coding or testing stages of development, however, when the repercussions of erroneous work have already been incurred. This paper presents a tentative model for predicting those parts of formal specifications which are most likely to admit erroneous inferences, in order that potential sources of human error may be reduced. The empirical data populating the model was generated during a series of cognitive experiments aimed at identifying linguistic properties of the Z notation which are prone to admit non-logical reasoning errors and biases in trained users.

Roughness perception in haptic virtual reality for sighted and blind people

Psychophysical functions for perceived roughness, relating ln (magnitude estimate of roughness) to ln (groove width), were obtained for blind and sighted participants in virtual reality using the PHANToM force feedback device. The stimuli were sinusoidal surfaces with groove widths between 0.675 mm and 20.700 mm. Group functions showed a similar nonlinearity to those obtained in physical reality using rigid probes (Klatzky, Lederman, Hamilton, Grindley, & Swendsen, 2003; Lederman, Klatzky, Hamilton, & Ramsay, 1999). Individual functions gave a different picture. Of 23 total participants, there were 13 with wholly descending linear psychometric functions, 7 with quadratic functions similar to the group function, and 3 with anomalous functions. Individual power law exponents showed no significant effects of visual status. All analyses gave a power law exponent close to −0.80. The implications for theories of roughness, methodologies of data analysis, and the design of haptic virtual reality interfaces are considered.

Time Perception and Depressive Realism: Judgment Type, Psychophysical Functions and Bias

The effect of mild depression on time estimation and production was investigated. Participants made both magnitude estimation and magnitude production judgments for five time intervals (specified in seconds) from 3 sec to 65 sec. The parameters of the best fitting psychophysical function (power law exponent, intercept, and threshold) were determined individually for each participant in every condition. There were no significant effects of mood (high BDI, low BDI) or judgment (estimation, production) on the mean exponent, n = .98, 95% confidence interval (.96–1.04) or on the threshold. However, the intercept showed a ‘depressive realism’ effect, where high BDI participants had a smaller deviation from accuracy and a smaller difference between estimation and judgment than low BDI participants. Accuracy bias was assessed using three measures of accuracy: difference, defined as psychological time minus physical time, ratio, defined as psychological time divided by physical time, and a new logarithmic accuracy measure defined as ln (ratio). The ln (ratio) measure was shown to have approximately normal residuals when subjected to a mixed ANOVA with mood as a between groups explanatory factor and judgment and time category as repeated measures explanatory factors. The residuals of the other two accuracy measures flagrantly violated normality. The mixed ANOVAs of accuracy also showed a strong depressive realism effect, just like the intercepts of the psychophysical functions. There was also a strong negative correlation between estimation and production judgments. Taken together these findings support a clock model of time estimation, combined with additional cognitive mechanisms to account for the depressive realism effect. The findings also suggest strong methodological recommendations.

Effects of age on phenomenology and consistency of flashbulb memories of September 11 and a staged control event

In two studies, the special status of flashbulb memories was investigated by contrasting the effects of age on the phenomenology and consistency of flashbulb memories of September 11, over a 2-year delay period, with those of a mundane staged control event: participants learning that they had not won a small prize. Flashbulb memories produced no significant age effects for either phenomenological characteristics or test-retest consistency, as predicted by Mathers (2004) emotional compensation hypothesis. By contrast, the control event resulted in significant age effects for phenomenological characteristics (e.g., specificity and the amount of detail recalled) but not for test-retest consistency. Furthermore, in both age groups, memories of September 11 were significantly more vivid, detailed, and consistent than control memories even though the test-retest interval was twice as long for flashbulb memories. In addition, correlations between consistency scores and ratings of rehearsal were positive for control memories but negative for flashbulb memories. The theoretical implications of these findings for research on cognitive aging and flashbulb memories are discussed.

Theoretical and empirical comparison of Luce’s choice model and logistic Thurstone model of categorical judgment

Theoretical predictions of the two models are analyzed and shown to be different if the number of categories is three or more. Then two common methods of testing mathematical models empirically are examined: (1) direct testing of predictions embodied in constraint equations, and (2) minimum chi-square methods. In the experimental investigation, two undergraduate subjects performed an eight-stimulus, 8-response category judgment of loudness in a neutral and a payoff biased condition. There were no significant departures from the Thurstone model, but substantial and significant departure from the choice model, especially in the biased condition. Chi-square tests were more powerful than constraint tests, but less good at identifying the source of conflict between data and theory.