The minimum principle and visual pattern completion

Summary The minimum principle states that a perceiver will see the simplest possible interpretation of a pattern. Some theorists of human perception take this principle as a core-explanatory concept. Others hold the view that a perceptual minimum principle is untenable. In two recent extensive surveys of the relevant literature a more differentiated position is taken: the minimum principle is not renounced in a definite way. In the research reported here, an intuitively appealing specification of a minimum principle is tested. An experiment on visual pattern completion was performed in which patterns were presented to subjects who traced the contours of the shapes they saw. It was predicted that there would be a preference for interpretations that describe a pattern as a set of separate shapes with minimal information load as computed by Leeuwenberg's coding language. However, only half of the responses given by the subjects were predicted by this specification of a minimum principle. It was further demonstrated that locally complex interpretations of junctions of contour elements are easily made, but not in order to attain globally minimal interpretations.     

Meaning resolution processes for words: A parallel independent model

Lexical ambiguity research over the last two decades is reviewed, with a focus on how that literature applies to understanding the resolution of meaning for words. Early models of ambiguity processing dealt almost exclusively with the time course of the effects of context on lexical access, in order to address the issue of modularity of lexical access. Newer models of ambiguity processing accommodate recent findings of early context effects that are contingent on both strength of context and meaning frequency. The most important contribution of these newer models of ambiguity processing is not to the modularity debate, but to investigation of the range of parameters affecting the entire meaning resolution process, including meaning access as well as the integration of meanings into context. As an example of this approach, we describe a simple quantitative model of meaning resolution that subsumes many other models as parametric variations.     

Serial processing in reading aloud: no challenge for a parallel model

K. Rastle and M. Coltheart (1999) challenged parallel models of reading by showing that the cost of irregularity in low-frequency exception words was modulated by the position of the irregularity in the word. This position-of-irregularity effect was taken as strong evidence of serial processing in reading. This article refutes Rastle and Coltheart's theoretical conclusions in 3 ways: First, a parallel model, the connectionist dual process model (M. Zorzi, G. Houghton, & B. Butterworth, 1998b), produces a position-of-irregularity effect. Second, the supposed serial effect can be reduced to a position-specific grapheme-phoneme consistency effect. Third, the position-of-irregularity effect vanishes when the experimental data are reanalyzed using grapheme-phoneme consistency as the covariate. This demonstration has broader implications for studies aiming at adjudicating between models: Strong inferences should be avoided until the computational models are actually tested.     

Random search with unequal search rates: Serial and parallel generalizations of McGill's model

A generalization of W. J. McGill's (1963, Stochastic latency mechanisms. In R. D. Luce, R. B. Bush, & E. Galanter (Eds.), Handbook of mathematical psychology (Vol. 1). New York: Wiley) random search model is examined in which the items in the search area are allowed to vary with respect to accessability. In order to analyze the model, it is equivalently described as a serial and as a parallel model. Predictions are derived for the means and variances of the interresponse times and of the number of recalls by time t. The predictions are compared to those made by the individual differences generalization of McGill's model proposed by D. G. Morrison (1979), Journal of Mathematical Psychology, 19, 307–315). In a final section, maximum likelihood estimation of parameters is discussed.     

Simple reaction time and statistical facilitation: a parallel grains model

A race-like model is developed to account for various phenomena arising in simple reaction time (RT) tasks. Within the model, each stimulus is represented by a number of grains of information or activation processed in parallel. The stimulus is detected when a criterion number of activated grains reaches a decision center. Using the concept of statistical facilitation, the model accounts for many classical effects on mean simple RT, including those of stimulus area, stimulus intensity, stimulus duration, criterion manipulations, redundant stimuli, and the dissociation between intensity effects on simple RTs and temporal order judgments. The model is also consistent with distributional properties of simple RTs.     

A note on the equivalence of the graded response model and the sequential model

This paper concerns items that consist of several item steps to be responded to sequentially. The item scoreX is defined as the number of correct responses until the first failure. Samejima's graded response model states that each steph=1,...,m is characterized by a parameterb _h , and, for a subject with ability, Pr(Xh; )=F(–b _h ). Tutz's general sequential model associates with each step a parameterdh, and it states that Pr(Xh;)= _r ^=1h G(–d _r ). Tutz's (1991, 1997) conjectures that the models are equivalent if and only ifF(x)=G(x) is an extreme value distribution. This paper presents a proof for this conjecture.     

On-line questionnaire completion time and personality test scores

Participants completed two well established questionnaires on line (HPI: Hogan Personality Inventory; and the HDS: Hogan Developmental Survey). Time taken to complete each study was correlated with scale scores from both questionnaires including the occupational scales derived from the HPI. Those who scored higher on Adjustment (Stability), and Prudence (Conscientiousness) but lower on Learning Approach took longer to complete the test. Those who scored higher on Stress Tolerance and Reliability took significantly longer than those with low scores on these measures. With only the exception of Diligent and Dutiful all correlations between Dark Side variables and time taken were negative, particularly Leisurely, Excitable and Imaginative. Regression showed that up to 6% of the time taken variance could be accounted for. Implications for measurement were considered.     

Serial and parallel processes in working memory after practice

Six young adults practiced for 36 sessions on a working-memory updating task in which 2 digits and 2 spatial positions were continuously updated. Participants either did 1 updating operation at a time, or attempted 1 numerical and 1 spatial operation at the same time. In contrast to previous research using the same paradigm with a single digit and a single dot, dual-task costs were not eliminated with practice. Costs of switching between digits and between spatial positions were found throughout practice, supporting the existence of a focus of attention in working memory that can hold 1 digit and 1 spatial position simultaneously, but is not expanded to hold 2 elements of the same kind. The results can be understood by assuming that observed limits on parallel processing, as well as on the capacity of the focus of attention, arise not from structural constraints but rather reflect the optimal configuration of the cognitive system for avoiding information cross-talk in a given task.     

Stimulus complexity and prospective timing: clues for a parallel process model of time perception

Whereas many studies have considered the role of attention in prospective timing, fewer have established relations between movement complexity and prospective timing. The present study aims at assessing to what extent motion complexity interferes with prospective timing and at delineating a neuropsychophysical plausible model. We have thus designed a visual paradigm presenting stimuli in sequential pairs (reference comparison interval). Stimuli are motionless or moving according to different complexities, and stimulus complexities are intermixed within each pair. To prevent a possible attention-sharing effect, no concurrent task was required. Our study suggests that movement complexity is a key component of duration perception, and that the relative judgement of durations depends on spatio-temporal features of stimuli. In particular, it shows that movement complexity can bias subjects’ perception and performance, and that subjects detect that comparison intervals are longer than reference before their end. In the discussion, we advocate that the classical internal clock model cannot easily account for our results. Consequently, we propose a model for time perception, based on a parallel processing between comparison interval perception and the reconstruction of the reference duration.     

Visual search time based on stochastic serial and parallel processings

Two stochastic latency models were developed in order to account for random fluctuations of the search time that the S consumed when he was asked to search for a single target number or one of two (or three) target numbers through the sets of small two-digit numbers randomly distributed on a white square. It was shown that the search time distribution for a single target number can be adequately described in terms of McGill’s two-step serial processing model. The parallel processing model whose structure is exponential was found to fit approximately the search time distributions for the first target number that the S detects among the two (or three) target numbers predesignated. This model, however, does not satisfactorily handle the long search times.     

On measuring the minimum detection time: A simple reaction time study in the time estimation paradigm

Kornblum's time estimation paradigm, together with the so‐called ‘race model’, provides an appealing alternative for measuring the ‘cut‐off’ which separates ‘true’ reaction times from anticipatory reaction times. However, the model is not precise enough to reveal the relation between the signal intensity and the ‘cut‐off’. Accordingly, Kornblum's model is extended with an emphasis on the measure of the ‘cut‐off’. Another aspect of the extension is to use a parametric method to analyse the data. In particular, it is assumed that the time estimation‐induced latency is gamma distributed and the signal‐induced latency is Weibull distributed, with the latter shifted by the ‘cut‐off’. The rationale behind the parametric assumption is discussed. For illustrative purposes, two pieces of experimental work are presented. Since the core of the race model is the assumption of an independent race between the time estimation process and the detection process, the first experiment tests whether, for the same signal intensity, the signal‐induced latency distribution is invariant across different time intervals; the second experiment tests whether, for the same time interval, the time estimation‐induced latency distribution is invariant across different signal intensity conditions. The data from the second experiment are also used to test various parametric assumptions in the model, which include the signal effect on the ‘cut‐off’. The new model fits the data well.     

Serial reaction time learning in preschool- and school-age children

Visuomotor sequence learning was assessed in 4- to 10-year-old children using a serial reaction time (SRT) task with both random and sequenced trials. One-half of the children received exposure to the sequence prior to performing the reaction time (RT) task. In Experiment 1, 7- and 10-year-old children demonstrated sequence-specific decreases in RT. As in the adult SRT literature, participants with explicit awareness of the sequence at the end of the session showed larger sequence-specific reaction time decrements than those without explicit awareness. Contrary to expectation, preexposure to the sequence did not reliably predict the level of awareness attained. Results from Experiment 2 indicate that 4-year-olds also demonstrate significant sequence learning on a variant of the SRT task. This article provides preliminary data regarding developmental changes in sequential learning and the development and use of implicit and explicit knowledge. Age-related differences emerged primarily in explicit rather than implicit knowledge.     

Use of temporal and spatial information in estimating event completion time

In this research, we investigated how students use temporal and spatial information to estimate the time to fill a tank. In Experiment 1, we evaluated the usefulness of a digital clock to calibrate temporal information and of an overflow tank to calibrate spatial information and investigated how component skills, such as judging volume, judging time, and performing mental calculations, correlate with estimation accuracy. In Experiment 2, we compared the usefulness of static and animated displays in order to test the prediction that static displays would be more useful when the fill rate remained constant but animated displays would be more useful when the fill rate changed. The findings, when combined with verbal reports, provide evidence regarding the use of four strategies that differ in their perceptual and arithmetic demands.     

Sample size planning with the cost constraint for testing superiority and equivalence of two independent groups

The allocation of sufficient participants into different experimental groups for various research purposes under given constraints is an important practical problem faced by researchers. We address the problem of sample size determination between two independent groups for unequal and/or unknown variances when both the power and the differential cost are taken into consideration. We apply the well‐known Welch approximate test to derive various sample size allocation ratios by minimizing the total cost or, equivalently, maximizing the statistical power. Two types of hypotheses including superiority/non‐inferiority and equivalence of two means are each considered in the process of sample size planning. A simulation study is carried out and the proposed method is validated in terms of Type I error rate and statistical power. As a result, the simulation study reveals that the proposed sample size formulas are very satisfactory under various variances and sample size allocation ratios. Finally, a flowchart, tables, and figures of several sample size allocations are presented for practical reference.     

Serial dependence in position occurs at the time of perception

Observers perceive objects in the world as stable over space and time, even though the visual experience of those objects is often discontinuous and distorted due to masking, occlusion, camouflage, or noise. How are we able to easily and quickly achieve stable perception in spite of this constantly changing visual input? It was previously shown that observers experience serial dependence in the perception of features and objects, an effect that extends up to 15 seconds back in time. Here, we asked whether the visual system utilizes an object’s prior physical location to inform future position assignments in order to maximize location stability of an object over time. To test this, we presented subjects with small targets at random angular locations relative to central fixation in the peripheral visual field. Subjects reported the perceived location of the target on each trial by adjusting a cursor’s position to match its location. Subjects made consistent errors when reporting the perceived position of the target on the current trial, mislocalizing it toward the position of the target in the preceding two trials (Experiment 1). This pull in position perception occurred even when a response was not required on the previous trial (Experiment 2). In addition, we show that serial dependence in perceived position occurs immediately after stimulus presentation, and it is a fast stabilization mechanism that does not require a delay (Experiment 3). This indicates that serial dependence occurs for position representations and facilitates the stable perception of objects in space. Taken together with previous work, our results show that serial dependence occurs at many stages of visual processing, from initial position assignment to object categorization.     

Serial dependence in the estimation of a car's arrival time

Serial dependence of a car's arrival time. We have studied the sequential structure of data in the arrival- time estimations. Forty participants estimated the arrival-time of a vehicle under two experimental conditions: real car and video-image. Various time series regression models were fit to our data, and residuals autocorrelations were computed. For each serial-dependence model, data were fit to three functions, namely, power, logarithmic, and linear. In both experimental conditions, the response magnitude (R) on a given trial in t was a function of the stimulus intensity (S) in such a trial (t) and of the S and R on t-1 and t-2. Assimilation effect to the previous responses and contrast effect to the previous stimuli has been found.