Looking time: Experimenter and instruction effects

A 2 by 3 factorial design was used to investigate the effects of the instructions and the presence of E on looking time. Two hundred thirty-nine college students viewed 30 colored stimuli of landscapes, single objects, and arrays of objects under three different sets of instructions, with E either present or absent while S viewed the stimuli. The results demonstrated that E’s presence depressed the time spent looking at the stimuli Evidence was also found suggesting that ambiguity in the typical instructions given Ss in looking-time experiments may result in artifactually long looking times. It was concluded that a more appropriate situation to investigate looking time would (1) utilize sham GSR instructions to reduce S’s uncertainty concerning the experiment’s purpose, and (2) arrange for E’s absence while S is viewing the stimuli     

Response programming and reaction time

A feature common in the literature is that, prior to responding, subjects have been able to preview the parameters of the movement they are required to make. This introduces the possibility of programming the movement before entering the reaction time period. It is argued that this has contributed to confusion in the literature, making it difficult to detect a consistent relationship between reaction time and motor task demands. Two experiments were conducted to clarify the position. Experiment I concealed the movement parameters prior to subjects responding ("no-preview" model), and this was contrasted with a study in the typical "preview" mode (Experiment II). It was concluded that the no-preview design is more appropriate to detecting changes in reaction time dependent on task parameters, and that the observed effects on reaction time reflect programming difficulty. A third experiment supported this conclusion     

Effects of visual-field and matching instruction on event-related potentials and reaction time

Vertical letter pairs were presented randomly in the left and right visual hemifields in a physical identity match and name identity match condition. The reaction times showed a right visual field superiority for name matches, and a left visual field superiority for physical matches. Event-related potentials to letter pairs showed a sequence of three waves: a negative wave (N2, around 270 msec), a positive wave (P3, around 500 msec), and a broad positive slow wave (SW, around 600-700 msec), respectively. P3 and SW amplitudes were consistently larger at the left hemisphere than at the right hemisphere, regardless of the field of stimulation. At both hemispheres, N2 waves were always larger to stimuli presented in the visual field contralateral to a hemisphere than stimuli presented in the visual field ipsilateral to a hemisphere. The positive waves (P3, SW) showed the opposite pattern: smaller amplitudes to stimuli that were presented contralaterally than stimuli that were presented ipsilaterally to a given hemisphere. These results were attributed to a shift in sustained negativity on the directly stimulated hemisphere, relative to the indirectly stimulated hemisphere, reflecting either sensory at attentional processes in the posterior cerebral hemispheres.     

Evaluating preschool children's preferences for motivational systems during instruction

Preschool teachers rely on several strategies for motivating children to participate in learning activities. In the current study, we evaluated the effectiveness of and preference for three teaching contexts in which embedded, sequential, or no programmed reinforcement was arranged. The embedded context included highly preferred teaching materials, the sequential context included highly preferred edible items for correct responding, and a control context included neither. In addition, an exclusively play-oriented activity was included as a fourth option to determine if one of the direct teaching contexts could compete with a relatively unstructured and exclusively child-led activity. All participants preferred the sequential context (use of high-quality consequences) over the embedded context (use of high-quality teaching materials), 2 of the 4 participants preferred some motivational system to none at all, and the play area was selected over all variants of the instructional contexts during the majority of trials. We found either no or small differences in correct responding in the different instructional contexts; however, rates of undesirable behavior were highest in the least preferred interaction area for 3 of the 4 participants. Implications for the design of effective and preferred teaching environments for young children are discussed.     

Response time distributions in multidimensional perceptual categorization

Three speeded categorization experiments were conducted using separable dimension stimuli. The form of the category boundary was manipulated across experiments, and the distance from category exemplars to the category boundary was manipulated within each experiment. Observers completed several sessions in each experiment, yielding 300–400 repetitions of each stimulus. The large sample sizes permitted accurate estimates of the response time (RT) distributions and RT hazard functions. Analyses of these data indicated: (1) RT was faster for stimuli farther from the category boundary, and this stochastic dominance held at the level of the RT distributions; (2) RT was invariant for all stimuli the same distance from the category boundary; (3) when task difficulty was high, errors were slower than correct responses, whereas this difference disappeared when difficulty was low; (4) small, consistent response biases appeared to have a large effect on the relation between correct and error RT; (5) the shape of the RT hazard function was qualitatively affected by distance to the category boundary. These data establish a rich set of empirical constraints for testing developing models of categorization RT.     

Response time accuracy in Apple Macintosh computers

The accuracy and variability of response times (RTs) collected on stock Apple Macintosh computers using USB keyboards was assessed. A photodiode detected a change in the screen’s luminosity and triggered a solenoid that pressed a key on the keyboard. The RTs collected in this way were reliable, but could be as much as 100 ms too long. The standard deviation of the measured RTs varied between 2.5 and 10 ms, and the distributions approximated a normal distribution. Surprisingly, two recent Apple-branded USB keyboards differed in their accuracy by as much as 20 ms. The most accurate RTs were collected when an external CRT was used to display the stimuli and Psychtoolbox was able to synchronize presentation with the screen refresh. We conclude that RTs collected on stock iMacs can detect a difference as small as 5–10 ms under realistic conditions, and this dictates which types of research should or should not use these systems.     

Responsiveness to verbal instruction during anesthesia: a pilot report

Five patients who were undergoing surgery were instructed to tense their forehead muscles. On 11 out of 12 trials, the patient's muscle tension was greater during the suggestion period than during the nonsuggestion condition.     

Systematic changes in the rate of instruction during driver training

Relatively little empirical evidence exists concerning variations in the quantity of instruction across learning in complex, real‐world tasks. Examination of driving instructors' remarks to pupils during actual lessons indicated the rate of comment declined in a coherent fashion across training, most consistent with a power function. The presence of a power law is reminiscent of learning functions found from studies in other skill domains when using indexes of performance, and suggests that quantity of instruction therefore might be used to assay the performance in complex tasks. The implications of these findings, for both basic and applied research, are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Response and time allocation in concurrent second-order schedules

Six pigeons were trained on two-key concurrent variable-interval schedules in which the required response was the completion of a fixed number of key pecks. When the required number of pecks was equal on the two keys, response- and time-allocation ratios under-matched obtained reinforcement rate ratios. A similar result was found when the required number of pecks was unequal, except that performance, measured in response terms, was biased to the shorter required number of pecks and was less sensitive to reinforcement-rate changes. No such differences were found in the data on time spent responding. When the variable-interval schedules were kept constant and the required numbers of pecks were systematically varied, response ratios changed inversely with the ratio of the required number of pecks, but time-allocation ratios varied directly with the same independent variable. Thus, on response measures, pigeons “prefer” the schedule with the smaller peck requirement, but on time measures they “prefer” the schedule with the larger peck requirement. This finding is inconsistent with a commonsense notion of choice, which sees response and time-allocation measures as equivalent.     

Response time modeling reveals multiple contextual cuing mechanisms

Contextual cuing refers to a response time (RT) benefit that occurs when observers search through displays that have been repeated over the course of an experiment. Although it is generally agreed that contextual cuing arises via an associative learning mechanism, there is uncertainty about the type(s) of process(es) that allow learning to influence RT. We contrast two leading accounts of the contextual cuing effect that differ in terms of the general process that is credited with producing the effect. The first, the expedited search account, attributes the cuing effect to an increase in the speed with which the target is acquired. The second, the decision threshold account, attributes the cuing effect to a reduction in the response threshold used by observers when making a subsequent decision about the target (e.g., judging its orientation). We use the diffusion model to contrast the quantitative predictions of these two accounts at the level of individual observers. Our use of the diffusion model allows us to also explore a novel decision-level locus of the cuing effect based on perceptual learning. This novel account attributes the RT benefit to a perceptual learning process that increases the quality of information used to drive the decision process. Our results reveal both individual differences in the process(es) involved in contextual cuing but also identify several striking regularities across observers. We find strong support for both the decision threshold account as well as the novel perceptual learning account. We find relatively weak support for the expedited search account.     

Teaching effective hand raising to children with autism during group instruction

We taught 3 children with autism to raise a hand or keep both hands down depending on their status (e.g., having heard a target word, possessing a specific item) using modeling, prompting, and reinforcement. All 3 children acquired accurate hand-raising skills in response to progressively more difficult discrimination tasks during group instruction. The implications for preparing children for general education settings are discussed.     

Response to instruction, English language learners and disproportionate representation: the role of assessment

Response to Intervention (RtI), a cyclical process that incorporates assessment and instruction, is both an approach to prevent learning difficulties and to establish student eligibility for special education. Assessment results are used to determine students' initial knowledge and skill, their need for successively more intensive levels of instruction, and to gauge their response to the intervention provided. Although this process is preferable to the IQ/achievement discrepancy model for determining the presence of specific learning disabilities, there are still a number of unresolved issues related to the assessment procedures in use. A pressing issue is the identification of measures and procedures that identify students with the greatest precision thus reducing inappropriate identification.     

Prompt-aided instruction of mirror-image discriminations: Abrupt prompt removal,time delay,and self-evaluation

This study compared three types of prompt-elimination procedures for helping children respond to left-right mirror-image stimuli. Three populations participated: normally developing preschoolers, students with mild mental retardation, and students with moderate mental retardation. All subjects were first trained to discriminate the stimuli in the presence of multiple pictorial prompts. These prompts required the subjects to discriminate the compounds on the basis of orientation. Then the prompts were eliminated, abruptly, with a time-delay procedure, or with a procedure requiring subjects to use the prompts to self-evaluate the accuracy of their responses. The results showed the following. First, most subjects rapidly discriminated the compound stimuli. Second, about 50% of the subjects of each population discriminated the task stimuli even when the prompts were abruptly removed. Time delay was highly effective with the normally developing preschoolers and students with mild mental retardation, but not with students with moderate mental retardation. The self-evaluation procedure was effective with all three populations.     

Response time models of delta plots with negative-going slopes

Delta plots (DPs) graphically compare reaction time (RT) quantiles obtained under two experimental conditions. In some research areas (e.g., Simon effects), decreasing delta plots (nDPs) have consistently been found, indicating that the experimental effect is largest at low quantiles and decreases for higher quantiles. nDPs are unusual and intriguing: They imply that RT in the faster condition is more variable, a pattern predicted by few standard RT models. We describe and analyze five classes of well-established latency mechanisms that are consistent with nDPs--exhaustive processing models, correlated stage models, mixture models, cascade models, and parallel channels models--and discuss the implications of our analyses for the interpretation of DPs. DPs generally do not imply any specific processing model; therefore, it is more fruitful to start from a specific quantitative model and to compare the DP it predicts with empirical data.     

An analysis of stimuli that influence compliance during the high-probability instruction sequence

When we evaluated variables that influence the effectiveness of the high-probability (high-p) instruction sequence, the sequence was associated with a precipitous decrease in compliance with high-p instructions for 1 participant, thereby precluding continued use of the sequence. We investigated the reasons for this decrease. Stimuli associated with the low-p instruction were systematically added and removed in the context of the high-p instructions, and results suggest that the stimuli associated with the low-p instruction influenced compliance with the high-p instructions.     

Response time analysis in cognitive tasks with increasing difficulty

In the present study, speeded tasks with differing assumed difficulties of the trials are regarded as a special class of simple cognitive tasks. Exploratory latent growth modeling with data-driven shape of a growth curve and nonlinear structured latent curve modeling with predetermined monotonically increasing functions were used to analyze individual response-time change with an increase in task difficulty and to investigate latent response-time growth variables in relation to cognitive ability. A task that required participants to state the number of dots in a set was used as an example of a simple cognitive task with increasing difficulty; the response latencies obtained in this task and the magnitude of RT-IQ correlations changed depending on the complexity of the trial.Consistent with theoretical predictions, the individual speed of baseline performance was only weakly negatively correlated with each of the three measures of cognitive ability used in the study. The rate of change in response times with increasing task difficulty, estimated as a generalized growth parameter in the exploratory latent growth model, was significantly negatively related to cognitive ability. Response times of less intelligent individuals increased more rapidly in the task with increasing difficulty than the response times of highly intelligent individuals. Within the nonlinear structured latent curve modeling, the growth of response times with an increase in task difficulty was best described by a function that approached an oblique asymptote after an initial interval of convexity. A slope of this oblique asymptote was significantly negatively related to cognitive ability; for less intelligent individuals, the asymptote of response-time change was steeper than that for more intelligent individuals. In addition, a parameter that determined the shape of response-time growth trajectories on the interval of convexity was related to one of the three measures of cognitive ability.