Language-independent conceptual "bugs" in novice programming

This article argues for tlic csistcncc 01 ' pcrsistcnt conccptual "bugs " in how noviccs program and understand programs. Tlicsc bugs arc not specific to a given programming language, but appcar to be language-independcnt. Purthermore, such bugs occur Tor noviccs from primary school to college age. Three different classcs of bugs-parallelisn~, intentionality, and egocentrism-are identified, and cxcmplificd through student errors. It is suggested that these classes of conccptual bugs arc rootcd in a "superbug, " thc default strategy that tl~crc is a hidden mind sorncwltcrc in tlic programtning lnngungc that has intelligcnt intcrprctivc powcrs. It is well known tliat studcnts Iiavc such pcrvasivc conceptual misunderstandings as novice programmers tliat correct programs carly in the learning process come as pleasant surprises. Even after a ycar or niorc of programming instruction, stu-dents liavc grcat difficulty predicting what output a program will have, in what ordcr conirnands will hc cxccutcd, or ir ~ writing arid debugging original programs lo solvc problcnis. Furtlicrlnorc, tlicsc problcliis arc not confincd to tlic vcry young stl~dcnt in clcmcntary scliool [I-51 and junior high [6] , but appear to pcrvadc tlic programniing activities of high scliool, college [7, 81, and mature adult studcnts as wcll. What arc tlic sourccs of these difficulties? Many of tlicsc conccptual difficulties arc confincd to specific implementations of particular prograniniing lariguagcs, and presumably can be ameliorated by re-designing the particular fcatures of those implcnicntations, or by means of auto-matic crror finders. In an excniplary study, Soloway, Bonar, and Ehrlich have shown how an invented while looping construct not available in Pascal was easier for novices to use in writing programs than the standard Pascal looping *The rcscarch discussed in this articlc was supportcd by the Spcncer Foundation an