Adaptive threshold estimation with unforced-choice tasks

This paper evaluates an adaptive staircase procedure for threshold estimation that is suitable for unforced-choice tasks—ones with the additional response alternativedon’t know. Within the framework of a theory of indecision, evidence is developed that fluctuations of the response criterion are much less detrimental to unforced-choice tasks than to yes/no tasks. An adaptive staircase procedure for unforced-choice tasks is presented. Computer simulations show a slight gain in efficiency ifdon’t know responses are allowed, even if response criteria vary. A behavioral comparison with forcedchoice and yes/no procedures shows that the new procedure outdoes the other two with respect to reliability. This is especially true for naive participants. For well-trained participants it is also slightly more efficient than the forced-choice procedure, and it produces a smaller systematic error than the yes/no procedure. Moreover, informal observations suggest that participants are more comfortable with unforced tasks than with forced ones.     

Hearing threshold shift during auditory magnitude estimation.

The purpose of the present experiment was to determine the extent of hearing threshold shift that may occur during an auditory magnitude-estimation task involving stimulus intensities as great as 80 dB sensation level. Also, possible influences of hearing threshold shift on numerical magnitude-estimation responses and magnitude-function slopes were investigated. Results indicated that hearing threshold shift was insignificant (1-2 dB). Consistent small increases in numerical magnitude responses were observed on a magnitude-estimation task where hearing thresholds were retested between stimulus presentations versus a magnitude-estimation task where hearing thresholds were not retested. The stability of auditory magnitude functions across different conditions in the current investigation was in agreement with vibrotactile magnitude-scaling behavior observed by Fucci, et al. in 1989 and 1991. The over-all results supported the concept of an absolute, internal sensory-scaling mechanism being operable during magnitude estimation of auditory stimuli as discussed by Zwislocki and Goodman in 1980.     

Adaptive robust estimation and testing

We examined nine adaptive methods of trimming, that is, methods that empirically determine when data should be trimmed and the amount to be trimmed from the tails of the empirical distribution. Over the 240 empirical values collected for each method investigated, in which we varied the total percentage of data trimmed, sample size, degree of variance heterogeneity, pairing of variances and group sizes, and population shape, one method resulted in exceptionally good control of Type I errors. However, under less extreme cases of non‐normality and variance heterogeneity a number of methods exhibited reasonably good Type I error control. With regard to the power to detect non‐null treatment effects, we found that the choice among the methods depended on the degree of non‐normality and variance heterogeneity. Recommendations are offered.     

Cue abstraction and ideal prototype abstraction in estimation tasks

This study investigates abstracted processes and introduces a new prototype abstraction model adapted to estimation tasks. This prototype abstraction model assumes that the processing of whole exemplar patterns supports the detection of the underlying statistics necessary for the abstraction of two extreme prototypes on the continuous criterion dimension of the task. The prototypes are stored in memory as valid reference points for future similarity-based judgments. This prototype model was compared with the cue abstraction model, which assumes that people abstract cue weights in learning and add the cue information from exemplars to infer their criterion values varying on the continuous dimension. This study hypothesises that the training mode and the number of exemplars in training interact and affect subsequent model performance at test. The results from an experiment confirmed this hypothesis and showed that observational training supports an efficient prototype abstraction and feedback training supports an efficient cue abstraction.     

Evaluation of three sensitivity measures in magnitude estimation tasks

Taking into account the studies about the measure of sensitivity in magnitude estimation tasks, we analyze the three most common measures used in this topic: Pearson's product-moment correlation between the logarithm of the stimulus and the logarithm of the response (R), the exponent of Stevens' power function (K), and the measure "M" proposed by Garriga-Trillo. Using a sample of participants greater than usual in psychophysical studies (180 participants), we designed an experiment with two sets of stimuli with different stimulus ranges. In each of these sets, we used two kinds of stimuli (line segments and squares). Our conclusions were: (1) we rejected the use of K as a sensitivity measure because the results provided by this index were the opposite of those expected when we compared the two stimulus ranges. (2) We also rejected the use of M because this measure is a linear transformation of Kendall's coefficient of concordance. (3) Lastly, we suggest the mathematical transformation proposed by Fisher to achieve a normal distribution, and recommend this transformation as the best sensitivity measure.     

Hierarchical Bayesian estimation and hypothesis testing for delay discounting tasks

A state-of-the-art data analysis procedure is presented to conduct hierarchical Bayesian inference and hypothesis testing on delay discounting data. The delay discounting task is a key experimental paradigm used across a wide range of disciplines from economics, cognitive science, and neuroscience, all of which seek to understand how humans or animals trade off the immediacy verses the magnitude of a reward. Bayesian estimation allows rich inferences to be drawn, along with measures of confidence, based upon limited and noisy behavioural data. Hierarchical modelling allows more precise inferences to be made, thus using sometimes expensive or difficult to obtain data in the most efficient way. The proposed probabilistic generative model describes how participants compare the present subjective value of reward choices on a trial-to-trial basis, estimates participant- and group-level parameters. We infer discount rate as a function of reward size, allowing the magnitude effect to be measured. Demonstrations are provided to show how this analysis approach can aid hypothesis testing. The analysis is demonstrated on data from the popular 27-item monetary choice questionnaire (Kirby, Psychonomic Bulletin & Review, 16(3), 457–462 2009), but will accept data from a range of protocols, including adaptive procedures. The software is made freely available to researchers.     

Small-sample characterization of stochastic approximation staircases in forced-choice adaptive threshold estimation

Despite the widespread use of up-down staircases in adaptive threshold estimation, their efficiency and usability in forced-choice experiments has been recently debated. In this study, simulation techniques were used to determine the small-sample convergence properties of stochastic approximation (SA) staircases as a function of several experimental parameters. We found that satisfying some general requirements (use of the accelerated SA algorithm, clear suprathreshold initial stimulus intensity, large initial step size) the convergence was accurate independently of the spread of the underlying psychometric function. SA staircases were also reliable for targeting percent-correct levels far from the midpoint of the psychometric function and performed better than classical up-down staircases with fixed step size. These results prompt the utilization of SA staircases in practical forced-choice estimation of sensory thresholds.     

Adaptive automation, trust, and self-confidence in fault management of time-critical tasks

An experiment on adaptive automation is described. Reliability of automated fault diagnosis, mode of fault management (manual vs. automated), and fault dynamics affect variables including root mean square error, avoidance of accidents and false shutdowns, subjective trust in the system, and operator self-confidence. Results are discussed in relation to levels of automation, models of trust and self-confidence, and theories of human-machine function allocation. Trust in automation but not self-confidence was strongly affected by automation reliability. Operators controlled a continuous process with difficulty only while performing fault management but could prevent unnecessary shutdowns. Final authority for decisions and action must be allocated to automation in time-critical situations.     

Assessing mood with affect-sensitive tasks

It is hypothesized that when an individual experiences a change in mood there are concomitant changes in performance at cognitive and psychomotor tasks. The present study attempts to identify tasks which are mood-sensitive. The nature of affect-sensitive tasks will yield information about how mood influences behavior. Further, to the extent that relationships between mood and affect-sensitive tasks are found, clients may be motivated to change their mood by a knowledge of expectable improvements in performance. Ten tasks and a mood-adjective checklist were administered to 106 subjects. Four of the tasks showed statistically significant relationships with self-reported mood. Results were promising for further investigations of affect-sensitive tasks.     

Assessing the Approximate Number System: no relation between numerical comparison and estimation tasks

Whether our general numerical skills and the mathematical knowledge that we acquire at school are entwined is a debated issue, which many researchers are still striving to investigate. The findings reported in the literature are actually inconsistent; some studies emphasized the existence of a relationship between the acuity of the Approximate Number System (ANS) and arithmetic competence, while some others did not observe any significant correlation. One potential explanation of the discrepancy might stem from the evaluation of the ANS itself. In the present study, we correlated two measures used to index ANS acuity with arithmetic performance. These measures were the Weber fraction (w), computed from a numerical comparison task and the coefficient of variation (CV), computed from a numerical estimation task. Arithmetic performance correlated with estimation CV but not with comparison w. We further investigated the meaning of this result by taking the relationship between w and CV into account. We expected a tight relation as both these measures are believed to assess ANS acuity. Crucially, however, w and CV did not correlate with each other. Moreover, the value of w was modulated by the congruity of the relation between numerical magnitude and non-numerical visual cues, potentially accounting for the lack of correlation between the measures. Our findings thus challenge the overuse of w to assess ANS acuity and more generally put into question the relevance of correlating this measure with arithmetic without any deeper understanding of what they are really indexing.     

Position of the egocentric reference and performance in line bisection and subjective vertical estimation tasks

Egocentric body coordinates such as the sagittal midline have been proposed to act as a reference for ballistic movements in extracorporeal space. Symmetrical functioning of the multiple neural structures processing sensory information would account for the normal sagittal position of the egocentric reference. According to this hypothesis a unilateral parietal lesion would induce a ipsilesional deviation which would prevent neglect patients from responding to stimuli that occur on that side. In this line of reasoning, an experimental manipulation of the position of the egocentric reference by way of a postural perturbation should have an effect on visuospatial tasks performance in normal subjects. Seventeen right-handed subjects were submitted in the dark to two visuomotor tasks: the adjustment of a luminescent rod to the vertical and the bisection of a luminescent line, either with the trunk and the head aligned at 0 degrees or with a 30 degrees trunk rotation to the right or to the left. Results revealed no significant effect of trunk rotation on the performance in both tasks. We discuss these findings and their implication for the understanding of the neglect syndrome.     

Perceptual and cognitive processes in time-to-contact estimation: Analysis of prediction-motion and relative judgment tasks

Three classes of task appear to involve time-to-contact (TTC) information: coincidence anticipation (CA) tasks, relative judgment (RJ) tasks, and interceptive actions (IAs). An important type of CA task used to study the perception of TTC is the prediction-motion (PM) task. The question of whether it is possible to study the perceptual processes involved in the timing of IAs using PM and RJ tasks is considered. A revised version of the tau hypothesis is proposed as an account of the perceptual information processing involved in the control of fast IAs. This draws on the distinction between “motor” and “cognitive” visual systems. It is argued that task variables affect whether “cognitive” information processing is involved in performance and can determine whether TTC information is used at all. Evidence is reviewed that suggests that PM and RJ tasks involve cognitive processing. It is argued that target viewing time, TTC at response initiation, amount of practice, and whether there is a period between target disappearance and response are task variables that determine whether cognitive processing will influence responding.     

Assessing anxiety with extrinsic Simon tasks

This article introduces two new indirect measures of anxiety that are based on the Extrinsic Affective Simon Task (EAST; De Houwer, 2003). The EAST differs from the more established Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) in that participants' responses to different trials within one block of trials are compared rather than performance between two different blocks of trials. Two studies led to the following results: (a) Both extrinsic Simon tasks for assessing anxiety showed only moderate internal consistencies, (b) one of the two tasks showed at least some convergent validity with an IAT for assessing anxiety, and (c) both tasks were dissociated from self-reported anxiety. Implications for future adaptations of the EAST for the indirect assessment of personality dimensions are discussed.     

Contextual interference effects with two tasks

The present study was intended to test whether the standard contextual interference effect would be observed when only two patterns were practiced in blocked or random schedules of multisegment movement tasks rather than three patterns which is the norm. In line with the basic effect, Blocked learners' performance was closer to ideal during acquisition, but Random learners had smaller errors at 24-hr. retention. In addition, random learners had better recall of the details of the patterns they had practiced. Learners' predictions of retention performance did not match the group differences actually observed.