Another approach to facilitating insight problem solving is to provide the problem solver with a problem-specific hint. Research that has investigated the hints approach, which has mainly focussed on visuo-spatial insight problems, is reviewed below. It will be concluded that hints are only helpful when they are tailored
specifically to the solution of the test problem.
Studies investigating the effects of hints can be traced back as early as Maier’s (1931) experiment o f the two-string problem, in which the experimenter appeared to accidentally brush against a string hanging from a ceiling which prompted the solver to attain the solution that items can be used as weights to swing one rope closer to the other. The underlying mechanisms for how hints operate are explained by insight problem solving theories. According to Progress Monitoring theory (MacGregor et al., 2001), hints expose the solver to problem-relevant information. Consequently, the solver is able to discover alternative moves when they experience criterion failure as a result of an impasse. In terms of Representational Change theory (Ohlsson, 1992), hints guide the solver to relax self-imposed constraints that otherwise block them from gaining insight into a problem.
The hints approach has predominantly been applied to facilitate performance on visuo-spatial problems (e.g., Burnham & Davis, 1969; Kaplan & Simon, 1990; Lung & Dominowski, 1985; Weisberg & Alba, 1981). For example, Kaplan and Simon (1990) tested the effectiveness of different types of hints to aid performance on the mutilated checkerboard problem. Verbal protocols were collected to examine
changes in the problem space more thoroughly. They found that when participants were given a ‘parity* hint regarding what they might do to solve the problem, performance was greater than when given an ‘impossible’ hint i.e., what actions would be impossible in facilitating solution. These results were interpreted to suggest that ‘parity’ hints guided the solver to focus on finding an appropriate problem representation within the specific domain of the problem space, whereas the
‘impossible’ hint directed the solver to generate other unhelpful representations of the problem. However, Kaplan and Simon’s observations do not indicate how
participants’ identified the need for a new problem representation or what processes were involved in generating a new representation (Bohannon, 1994). Furthermore, it is not known whether such hints are generalisable to other insight problems (Cheung, Kong, Li, Wong, & McBride-Chang, 2005).
Several studies have developed hints to facilitate performance on the nine-dot problem, which is another visuo-spatial problem. Burnham and Davis (1969) gave participants an instruction to extend the line beyond the boundary o f the nine-dot square. A training effect o f 23% was found in the hint condition, whereas a later study by Lung and Dominowski (1985) found a 34% training effect. However, Weisberg and Alba (1981, Experiment 1) found 100% improvement when this hint was combined with a drawn line that was part of the solution to the problem. Weisberg and Alba’s result is not surprising as giving hints that are directly related to the
problem solution narrow the problem space and provide a critical starting point for the solution process.
Few studies have investigated the effects of hints, sometimes referred to as strategic instructions, in solving verbal insight problems (e.g., Ansburg &
hints utilised by these studies have differed in terms o f their specificity. That is, some studies have provided general hints such as re-interpreting a problem several times to avoid making incorrect assumptions (Ansburg & Dominowski, 2000; Wicker et al.,
1978), with training effects ranging between 48% (Ansburg & Dominowski, 2000) and 63% (Wicker et al., 1978, Experiment 2). On the other hand, others have investigated whether giving hints that were directly related to problem solution improved performance on several verbal insight problems such as the following (Perfetto et al., 1983, p. 25):
‘A man living in a small town in the U.S. married twenty different women in the same town. All are still living and he has never divorced one o f them. Yet, he has broken no law. Can you explain?’
Perfetto et al. (1983) presented participants with hints, referred to as ‘clues’ in their study, prior to problem solving. For example, the clue related to the above problem was ‘A minister marries several people each week’. The solution was that the man was a minister/priest. It was found that only the participants who were explicitly told that the clue would help them to solve the problems performed well (54%). It is surprising that the training effect was not much higher as the clue was directly linked to the problem solution. However, participants who were not prompted to use the clues performed as poorly (29%) as those who were not given any hints at all (19%). An important implication of these findings is that to be able to use new knowledge or problem-relevant hints, it is critical that participants are made aware o f the relevance of this knowledge.
In summary, research suggests that the hints approach facilitates positive transfer although the transfer effect is higher when the hint is directly linked to or gives a way a part o f the solution to a problem. However, a general criticism of the hints approach is that, in providing a hint, the novelty o f the problem is diminished whilst prompting the solution to the problem. Further, in order to be able to devise a useful hint, the solution to a problem must be known in advance. From an applied perspective, the generalisablity of solution-specific hints is likely to be limited, particularly given the variability among insight problems. In any case, everyday problems are not accompanied by explicit hints and research indicates that problem solvers habitually default to past knowledge and experiences to aid them in their problem solving (Knoblich et al., 1992; Ohlsson, 1992; Sternberg & Davidson, 1995).