Schema Creation in Programming

The creation of plan schemes is examined in a naturalistic, longitudinal study of problem solving. Ten novice programmers each wrote eight Pascal programs to solve a series of problems. Their protocols were analyzed to determine how declarative programming knowledge was used to create simple procedural program plans, and how the simple plans were used to create complex plans. Plan creation showed a process of backward development, from the goal to the plan focus, that port of the plan that directly implements the goal. Once defined; it is expanded to create the complete plan, showing backward development of plan parts from the focus. Once the plan is complete, it may be stored as a plan schema and retrieved in subsequent problem solving. The plan will then show forward development as it is implemented in schema order, the order in which plan pieces occur in the finished program. The change from backward development during creation to forward development after retrieval was strongly evident in the statistical analysis of the protocol data. Previous studies of novice programming, which showed only forward development, ore explained as special cases of this more general model, cases in which schema knowledge was available to the problem solver.     

The Advanced Programmer's Reliance on Program Semantics: Evidence from some Cognitive Tasks

This study examined the effects of programming expertise on the semantic processing of computer programs. Experiment 1 showed that sensitivity to semantic changes (i.e. changes of actual program functions) in a BASIC program recognition task increased with programming experience. No such pattern was observed for surface changes (i.e. changes of program syntax without functional alterations). The magnitude of semantic priming for BASIC keywords in a lexical decision task also increased with expertise, but the pattern was not found with normal English priming. In Experiment 2, novice BASIC programmers detected more semantic changes than the controls (non-programmers) in BASIC programs; the reverse was found for surface changes. Both the controls and the novices detected more semantic than surface changes in English passages. The BASIC priming effect was found only with the novices whereas English priming was demonstrated with both the control and the novice participants. The present findings support the view that the programming expert relies particularly on semantic processing and such reliance is specific to programming activities. Practical implications of the present results are discussed.     

A theoretical and empirical comparison of mainframe,microcomputer, and pocket calculator pseudorandom number generators

This article presents an extensive theoretical and empirical analysis of the pseudorandom number generators provided by subroutine libraries (NAG, CERN, IMSL, and ESSL), statistical and simulation software packages (GLIM, SAS, SPSS, DATASIM, ESSP, and LLRANDOMII), builtin functions of programming languages (APL, Turbo Pascal, Advanced BASIC, GW-BASIC, and QBASIC), and autoimplemented algorithms (Fishman & Moore, 1986; Wichmann & Hill, 1982; Van Es, Gill, & Van Putten, 1983). On the basis of these analyses, it is concluded that most of the built-in functions of the software packages that were tested can be used safely. In addition, it is concluded that the Wichmann and Hill algorithm is a good choice if only single-precision arithmetic is available, but that a prime-modulus multiplicative congruential generator with modulus 2³¹ ?1 and multiplier 16,807 is a better choice if double-precision arithmetic is available, and that the same generator with multiplier 62,089,911 or 742,938,285 is the best choice if extended-precision arithmetic is available. A Turbo Pascal and a VS FORTRAN program for the latter are given in the Appendixes.     

Realizing complex delayed intentions in young and old adults: The role of planning aids

Although it has been suggested that the delayed realization of intended actions should benefit from appropriate intention planning, empirical evidence on this issue is scarce. In three experiments, we examined whether and which planning aids provided in the intention formation phase affect delayed intention realization in young and old adults. One finding was that intention planning directly affected delayed intention realization: instructing participants to include the cue for appropriate intention initiation in their plans benefited delayed performance. Another finding was that older adults' performance was improved when they were guided in structuring their plan in combination with guidance in implementing this plan after a delay. In sum, the results point to the importance of plan-related factors for understanding the delayed realization of intended actions.     

Pascal external functions for Strawberry Tree’s “Analog Connection Workbench” on the Macintosh

Strawberry Tree Incorporated is one of several manufacturers of input-output boards for the Macintosh computer. The Analog Connection Workbench program (Strawberry Tree Inc.) provides an icon-based programming system for these input-output boards that has most of the functions that are necessary to implement behavioral experiments. However, experimental psychologists may frequently encounter needs that the Workbench program cannot easily meet. Because the Workbench is programmed in C, whereas many psychologists are more expert in programming in Pascal, we describe, in tutorial fashion, how the user may define new external functions in Pascal on the Macintosh and integrate these functions into the icon-based Workbench programming system.     

Stimulus structures and mental representations in expert comprehension of computer programs

Comprehension of computer programs involves detecting or inferring different kinds of relations between program parts. Different kinds of programming knowledge facilitate detection and representation of the different textual relations. The present research investigates the role of programming knowledge in program comprehension and the nature of mental representations of programs; specifically, whether procedural (control flow) or functional (goal hierarchy) relations dominate programmers' mental representations of programs. In the first study, 80 professional programmers were tested on comprehension and recognition of short computer program texts. The results suggest that procedural rather than functional units form the basis of expert programmers' mental representations, supporting work in other areas of text comprehension showing the importance of text structure knowledge in understanding. In a second study 40 professional programmers studied and modified programs of moderate length. Results support conclusions from the first study that programs are first understood in terms of their procedural episodes. However, results also suggest that a programmer's task goals may influence the relations that dominate mental representations later in comprehension.     

Accurate display timing using an enhanced BASIC for the Tandy Color Computer

The general suitability of the Tandy Color Computer as an inexpensive laboratory microcomputer is discussed. A program is described that adds several useful timing-related functions to the native BASIC in the Tandy Color Computer, thus allowing BASIC to be used for programming experiments involving tachistoscopic displays and reaction times.     

Less is more: The effect of multiple implementation intentions targeting unhealthy snacking habits

Implementation intentions have been shown to effectively change counter‐intentional habits. Research has, however, almost solely been concerned with the effectiveness of a single plan. In the present research, we investigated the behavioral and cognitive implications of making multiple implementation intentions targeting unhealthy snacking habits and its underlying processes, linking multiple habitual snacking cues to healthy alternatives. Study 1 revealed that formulating multiple implementation intentions was not effective in decreasing unhealthy snacking, whereas formulating a single plan successfully induced behavior change. By using a lexical decision task in Study 2, it was found that when making a single plan, but not multiple plans, the healthy alternative became cognitively more accessible in response to a critical cue prime than the habitual response. However, when making additional plans in an unrelated domain, the negative effects of making multiple plans were absent. In sum, the current findings suggest that formulating multiple implementation intentions is ineffective when changing unwanted behavior. These reduced effects of multiple implementation intentions do not occur when making the plan but are rather due to interference in the enacting phase of the planning process. Copyright © 2013 John Wiley & Sons, Ltd.     

Cue-task associations in task switching

Cognitive flexibility can be studied using the task-switching paradigm. This paradigm requires subjects to adapt behaviour to changing contexts as indicated by a cue. In our study, we addressed the question of how cue-based implementation of mental “task sets” occurs. We assumed that cues build up associations to the tasks that they indicate. These associations lead to retrieval of the associated task set once the cue shows up again. In three experiments, we tested this assumption using a negative transfer paradigm. First participants were exposed to one cue-task mapping. After a training phase, the cue-task mapping changed in either of two ways. Whereas one group of participants got new cues, the other experienced a reversal of the learnt cue-task mapping. Our results show that participants build up cue-task associations and that these formerly learnt associations can hamper the implementation of new cue-task mappings (particular with mapping reversal). Prolonged preparation time decreased the cost of changing the cue-task mapping but did not change the overall pattern of results.     

Apple slide tachistoscope

We outline a BASIC program and subsidiary machine language timing routines that enable the Apple II series of computers to be employed as control devices for the tachistoscopic presentation of 35-mm slides and the collection of response latencies. The program is functional for experiments that require pictorial stimuli to be presented in up to three separate fields, with precise display times, precise interstimulus and intertriai intervals, and the collection of manual or vocal reaction times with millisecond accuracy. The major advantages of this system are that initial setup costs are substantially lower than those for other similar systems (e.g., Loftus, Gillispie. Tigre, & Nelson, 1984) and that user customization of the program may be accomplished by anyone possessing rudimentary knowledge of the BASIC programming language.     

Problem solving and the development of abstract categories in programming languages

The question of how novice and expert computer programmers represent and use programming concepts is addressed here. Lines of programming code forming three complete programs were presented one at a time and in random order in a multitrial free recall procedure. Qualitative and quantitative measures revealed clear but different subjective organization in the two groups. The novices used a syntax-based organization, whereas the experts used a more abstract hierarchical organization based on principles of program function.     

When do professional psychologists need professional programmers’ tools?

It is fairly straightforward to write a small program for a small computer, even using a relatively slow and unstructured language such as BASIC. However, current experiments in psychopharmacology require the system integration and data management services provided by large programs running on 256K microcomputers, and the efficient development of such programs requires the use of structured languages such as Pascal.     

Facilitation and inhibition caused by the orienting of attention in propositional reasoning tasks

In an attempt to study the orienting of attention in reasoning, we developed a set of propositional reasoning tasks structurally similar to Posner's (1980) spatial cueing paradigm, widely used to study the orienting of attention in perceptual tasks. We cued the representation in working memory of a reasoning premise, observing whether inferences drawn using that premise or a different, uncued one were facilitated, hindered, or unaffected. The results of Experiments 1a, 1b, 1c, and 1d, using semantically (1a-1c) or statistically (1d) informative cues, showed a robust, long-lasting facilitation for drawing inferences from the cued rule. In Experiment 2, using uninformative cues, inferences from the cued rule were facilitated with a short stimulus onset asynchrony (SOA), whereas they were delayed when the SOA was longer, an effect that is similar to the “inhibition of return” (IOR) in perceptual tasks. Experiment 3 used uninformative cues, three different SOAs, and inferential rules with disjunctive antecedents, replicating the IOR-like effect with the long SOAs and, at the short SOA, finding evidence of a gradient-like behaviour of the facilitation effect. Our findings show qualitative similarities to some effects typically observed in the orienting of visual attention, although the tasks did not involve spatial orienting.     

EVALUATION OF TACTILE PROMPTS WITH A STUDENT WHO IS DEAF,BLIND, AND MENTALLY RETARDED

We provided tactile cues to a student who was deaf, blind, and mentally retarded to guide her performance on a variety of packaging tasks. The student had previously received extensive training on multiple packaging and sequencing tasks through her vocational education program. Although she was able to complete these tasks, each change in materials necessitated that similar levels of retraining be conducted in order for her to perform revised tasks. Tactile cues were introduced and evaluated through a multiple baseline with sequential withdrawal design for two envelope-stuffing tasks and one bagging task. Results indicated that the tactile prompts were effective in guiding her performance on the training task and in promoting generalization to novel tasks and cues. Continued use of the cues was necessary to maintain the student's performance. Our findings suggest that tactile prompts function similarly to picture prompts and may be an effective alternative external prompting system for persons for whom picture prompts would not be appropriate.     

Parental recognition in the rat

Infant rats were tested in a 2-choice test for their preference for (a) their mother vs an alien mother, (b) their father vs an alien father and (c) their father, whom they had never experienced, vs an alien father. Pups were able to recognize their mother and showed a preference for her for the duration of the experiment. Pups could also recognize their father, even if they had never previously experienced him. However, they showed a reversal in preference for their father during the experiment, preferring their father at Days 10-14, but preferring an alien father at Days 18-22. It is concluded that fathers are recognized by general cues of kinship through “phenotype matching”, whereas mothers assume a positive reinforcing value and are recognized by individual cues.     

Sampling plans for fitting the psychometric function

Research on estimation of a psychometric function psi has usually focused on comparing alternative algorithms to apply to the data, rarely addressing how best to gather the data themselves (i.e., what sampling plan best deploys the affordable number of trials). Simulation methods were used here to assess the performance of several sampling plans in yes-no and forced-choice tasks, including the QUEST method and several variants of up-down staircases and of the method of constant stimuli (MOCS). We also assessed the efficacy of four parameter estimation methods. Performance comparisons were based on analyses of usability (i.e., the percentage of times that a plan yields usable data for the estimation of all the parameters of psi) and of the resultant distributions of parameter estimates. Maximum likelihood turned out to be the best parameter estimation method. As for sampling plans, QUEST never exceeded 80% usability even when 1000 trials were administered and rendered accurate estimates of threshold but misestimated the remaining parameters. MOCS and up-down staircases yielded similar and acceptable usability (above 95% with 400-500 trials) and, although neither type of plan allowed estimating all parameters with optimal precision, each type appeared well suited to estimating a distinct subset of parameters. An analysis of the causes of this differential suitability allowed designing alternative sampling plans (all based on up-down staircases) for yes-no and forced-choice tasks. These alternative plans rendered near optimal distributions of estimates for all parameters. The results just described apply when the fitted psi has the same mathematical form as the actual psi generating the data; in case of form mismatch, all parameters except threshold were generally misestimated but the relative performance of all the sampling plans remained identical. Detailed practical recommendations are given.     

Are People Successful at Learning Sequences of Actions on a Perceptual Matching Task?

We report the results of an experiment in which human subjects were trained to perform a perceptual matching task. Subjects were asked to manipulate comparison objects until they matched target objects using the fewest manipulations possible. An unusual feature of the experimental task is that efficient performance requires an understanding of the hidden or latent causal structure governing the relationships between actions and perceptual outcomes. We use two benchmarks to evaluate the quality of subjects' learning. One benchmark is based on optimal performance as calculated by a dynamic programming procedure. The other is based on an adaptive computational agent that uses a reinforcement-learning method known as Q-learning to learn to perform the task. Our analyses suggest that subjects were successful learners. In particular, they learned to perform the perceptual matching task in a near-optimal manner (i.e., using a small number of manipulations) at the end of training. Subjects were able to achieve near-optimal performance because they learned, at least partially, the causal structure underlying the task. In addition, subjects' performances were broadly consistent with those of model-based reinforcement-learning agents that built and used internal models of how their actions influenced the external environment. We hypothesize that people will achieve near-optimal performances on tasks requiring sequences of action-especially sensorimotor tasks with underlying latent causal structures-when they can detect the effects of their actions on the environment, and when they can represent and reason about these effects using an internal mental model.     

Online Story Comprehension among Children with ADHD: Which Core Deficits are Involved?

Children with ADHD have difficulty understanding causal connections and goal plans within stories. This study examined mediators of group differences in story narrations between children ages 7-9 with and without ADHD, including as potential mediators both the core deficits of ADHD (i.e., inattention, disinhibition, planning/working memory) as well measures of phonological processing and verbal skills. Forty-nine children with ADHD and 67 non-referred children narrated a wordless book and completed tasks assessing the core deficits of ADHD, phonological processing, and verbal skills. Results revealed that, although no shorter than those of non-referred children, the narratives of children with ADHD contained fewer elements relating to the story's causal structure and goal plan. Deficits in sustained attention accounted for the most variance in these differences. Results have implications for understanding and ameliorating the academic problems experienced by children with ADHD.     

What it costs to implement a plan: Plan-level and task-level contributions to switch costs

Four experiments were conducted to identify the costs of implementing a plan in the task span procedure, which requires subjects to retrieve the task to perform on the current target from a list of planned tasks in memory. Experiment 1 compared switch costs in the task span procedure with switch costs in the explicit task-cuing procedure, which presented cues indicating the task to perform on each target. Switch costs were greater in the task span procedure. Experiments 2-4 were designed to identify the sources of this difference. Experiment 2 showed that the requirement of establishing a correspondence between the list of task names and the list of targets contributed to switch costs. Experiment 3 showed that retaining lists of similar task names produced greater switch costs than did retaining lists of dissimilar task names. Experiment 4 showed that memory load had no effect on switch costs. The results are discussed in terms of the interaction between plan-level and task-level processing in the implementation of plans.