MKTG2112 · Consumer Behaviour
Individual Decision Making: EKB, Involvement, Risk & Decision Rules
This topic opens the consumer's head: how much effort a purchase deserves, and how the choice is actually made. It covers the habitual–limited–extended effort continuum, involvement and the six types of perceived risk, the EKB model of the decision process, the nested sets a brand must climb into (evoked → consideration), and the compensatory vs non-compensatory rules consumers use to choose. It is examined as short-answer / essay, so you classify a decision, trace it through EKB, and explain how different decision rules can pick different brands.
What this chapter covers
- 011. Three decision types by effort: habitual behaviour → limited problem solving → extended problem solving
- 022. Involvement: the perceived personal importance/relevance that drives search and effort
- 033. Six perceived-risk types: financial, performance/functional, physical, social, psychological, time
- 044. The EKB model: problem recognition → information search → evaluation → purchase → post-purchase
- 055. Information search: internal (memory) vs external (sources) — consumers minimise costly effort
- 066. Sets: total → awareness → evoked set → consideration set → choice (plus inert/inept sets)
- 077. Compensatory rules: a strong attribute offsets a weak one (simple/weighted additive) — high involvement
- 088. Non-compensatory rules: conjunctive, disjunctive, lexicographic, elimination-by-aspects — low involvement
Decision type, EKB stages & decision rules (short answer, 8 marks)
- 3 marks (type + both drivers)Classify: extended problem solving — high involvement (high price, personal relevance, infrequent, unfamiliar) and high perceived risk across financial, performance and social types, prompting extensive internal and external search.
- 2 marksIntervene at information search / evaluation of alternatives: owned review content and an in-store trial reduce performance and financial risk, moving the brand from the awareness set into the evoked/consideration set.
- 3 marksContrast the rules: under a compensatory (weighted-additive) rule, a camera's outstanding image quality can offset a high price, so the highest total score wins. Under a lexicographic rule, the consumer ranks attributes (say price first) and simply buys the cheapest acceptable camera, ignoring the image-quality advantage — so the two rules can select different brands from identical data.
Key terms
- Extended vs limited vs habitual problem solving
- The effort continuum. Habitual = low-cost, frequent, automatic choices with little search; limited = some effort using simple rules; extended = high-involvement, infrequent, unfamiliar purchases with extensive search and evaluation.
- Perceived risk
- The uncertainty a consumer feels about a purchase, in six forms — financial, performance (functional), physical, social, psychological and time. Consumers act to reduce risk (warranties, reviews, trials), which marketers can exploit.
- EKB model
- The Engel–Kollat–Blackwell model of consumer decision making: problem (need) recognition → information search → evaluation of alternatives → purchase → post-purchase behaviour, with internal/external search and dissonance as components.
- Evoked / consideration set
- The nested narrowing of options: from the total set to the awareness set to the evoked set (alternatives actively recalled) to the consideration set (those genuinely considered) to choice. Marketing's job is to move a brand inward toward choice.
- Compensatory decision rule
- A high-involvement rule where a strong attribute can offset a weak one, typically via simple or weighted additive scoring (the multi-attribute logic). The option with the best overall balance can win despite a weakness.
- Non-compensatory decision rule
- A rule where a weakness cannot be offset: conjunctive (meet a cut-off on all attributes), disjunctive (excel on at least one), lexicographic (rank attributes and pick the best on the most important), or elimination-by-aspects.
Individual Decision Making: EKB, Involvement, Risk & Decision Rules FAQ
How do I tell extended from limited from habitual problem solving?
Look at involvement, frequency and familiarity. Habitual = cheap, frequent, familiar, automatic, almost no search (your usual coffee). Limited = a bit of thought using simple rules (a mid-priced everyday item). Extended = expensive, infrequent, unfamiliar and personally important, with extensive internal and external search and careful evaluation (a car, a laptop). Always justify with involvement AND perceived risk.
What's the difference between the evoked set and the consideration set?
The evoked set is the group of alternatives a consumer actively recalls (from memory plus retail prominence) when a need arises. The consideration set is the subset they would actually consider buying. Brands in neither — the inert (no opinion) or inept (rejected) sets — are out of contention, so a key marketing goal is to move a brand inward from awareness toward the consideration set and choice.
When do consumers use compensatory versus non-compensatory rules?
Compensatory rules suit high-involvement decisions where consumers hold strong beliefs and are willing to weigh many criteria, letting a strength offset a weakness. Non-compensatory rules (conjunctive, disjunctive, lexicographic, elimination-by-aspects) suit low-involvement or limited decisions where consumers shortcut — a weakness on a key attribute simply rules an option out. The same data can yield different choices depending on the rule.
How is this topic examined?
As short-answer / essay: classify a decision (type + involvement + risk), trace it through the EKB stages in order with an intervention point, and explain how decision rules work — often by showing two rules selecting different options from the same table. The conjunctive-versus-lexicographic distinction is a recurring trap.
Exam move
Build three reflexes. First, classify-and-justify: for any purchase, state habitual/limited/extended AND back it with involvement and the relevant perceived-risk types. Second, recite the EKB stages in order and be able to attach a marketing intervention to each, especially search and evaluation. Third, master the decision rules by mechanism, not name — practise a small attribute table and run both a compensatory (weighted-additive) and a non-compensatory rule (lexicographic, conjunctive) over it to show they can choose different brands. Watch the conjunctive-vs-lexicographic trap (conjunctive = meet a cut-off on ALL attributes; lexicographic = rank and pick best on the top one).
