If you try to remember the items in a list displayed, you will notice that you remember items displayed first and last items the best, the middle items the worst. This effect is known as Serial Position Effect. The serial position effect is the propensity of an individual to remember the first and the last items in a series the best. This was first postulated by German psychologist Hermann Ebbinghaus by conducting numerous memory experiments on himself.

Influence on Memory

The effect is due to two memory recall biases namely, the primacy effect and the recency effect (figure 1).

1. Primacy effect : Items displayed at the beginning of a list are recalled with greater accuracy than items in the middle of a list.
2. Recency effect : Items that appear at the end of a list are also more likely to elicit better recall than items presented in the middle of a list

Figure 1 : Serial Position Curve

The design of the user interfaces has implications on the memory system of the user, affecting the ability to recall and retrieve. Presenting long lists of information induces consequential strain on our attention span where current research lacks sufficient empirical data. Below is an example of serial position effect being induced in a shopping site.

Is that really the case for every type of information being displayed to us on a shopping platform ? What if something really catches our attention from the middle of the list ? Does it effect our decision to buy a product ? To answer questions like this, we must consult current research articles that provide insight into our attention span and our recall ability while shopping online.

Influence of serial position effect on user decision

So far we know that such an effect makes our cognitive system ignore the visual content in the middle part of a free recall. Free recall is essentially reproducing the remembered items in any order. Research tells that during a visual presentation sequence, there is an error in the Retrospective Evaluation (RE) of our cognitive system. Retro..what ?

In simple terms, RE means looking back and analyzing

In 1996, Hsee postulated the General Evaluability Theory which states that “All judgements and decisions in the shopping environment are due to one (or combinations) of two basic evaluation modes (EM)” as shown in Figure 2.

Figure 2 : Two Evaluation Modes that influence decision making

1. Joint Evaluation Mode (JE) : Multiple options appears at the same time and makes our system use comparative analysis. Users are dependent on theory and logic when making decisions.
2. Separate Evaluation Mode (SE) : Multiple options appears separately and hence are evaluated independently by our system. Users are dependent on feelings and emotions when making decisions.

One of the main highlight of the evaluation research done on shopping sites, conclude that JE is more prone to primacy effect and SE to recency effect. It was also found that only two factors that affected user’s decision making were product attributes and prices (Figure 3). Evidently, the experiment environment was a stimulated web purchase. The actual shopping environment would be affected by many factors like environment, personal preferences, product category etc. Hence, distracting factors were eliminated and a virtual shopping scene were conducted for research purposes.

Figure 3 : Product attributes and its price influenced users decision the most

Primacy and Anchoring effect

Now we know that information displayed as cards, results in extreme Joint Evaluation (JE) by our system which is prone towards primacy effect, induces a bias known as Anchoring. It refers to the common human tendency to rely too heavily on the first piece of information. While shopping online users are effected with product primacy and pricing primacy.

1. Product Primacy : When users see the product first. In this case, they evaluate the product solely on the looks or design.
2. Pricing Primacy : When consumers see a price before the product. Here they tend to evaluate the product’s worth more critically.

What works for someone else may not work for you. So, it’s contextual, right? But studies have been conducted on a very large data-set, to confirm the aforementioned findings. In study published in 2007, researchers studied “recommender systems” ; systems that help consumers choose which product to buy. Subjects were shown randomized variations of tent order. All the tents had different features (eg, waterproofing, closures etc), yet consumers choose the first tent over the rest by a factor of 2.5X, no matter what the tent was.

Effect on free recall

What happens when we attempt free recall after serial position effect is induced, that is, trying to reproduce the items remembered in any order ? In an immediate free recall, words recalled successively tend to come from nearly serial positions.This is known as Lag Recency effect. Although recency effects in recognition memory are long lived and resistant to memory, in a free recall, they are short lived and extremely vulnerable to interference.

When experiments were conducted on participants that performed immediate, delayed and continuous distractor free recall under conditions designed to minimize rehearsal, the lag recency effect was observed in all the three types. When there was an end-of-list distractor task, recency effect was eliminated. But it reinstated when participants performed a distractor task in between each of the list items and at the end of the list. This is validated as Long-term Recency. Another viewpoint exists involving Conditional Response Probability (CRP), that measures how one recall follows another.

The serial position curve in free recall results jointly from the probability of first recall and CRP curves. The experiments prove that either the end-of-list recency nor the lag recency depend on rehearsal.

Conclusion

Being aware of serial position effect and how it is manipulated in information visualization puts one in a good position while evaluating a product and deciding whether its purchase is worth. The reasons people buy and don’t buy are complex and contextual. Very large data-sets confirm the findings mentioned in this article and understanding its effect on our decision making while shopping online is liberating. There is no clear-cut and there’s no silver bullet to avoid them but worth keeping in consideration while on a hunt to buy a cute coffee cup for your crush.

References

1. Influence of Commodity Presentation Mode on Online Shopping Decision Preference Induced by the Serial Position Effect. Zhiman Zhu et. al
2. Searching for Experience on the Web: An Empirical Examination of Consumer Behavior for Search and Experience Goods. Huang et. al
3. Contextual Variability and Serial Position Effects in Free Recall. Marc W. Howard and Michael J. Kahana
4. An examination of the continuous distractor task and the long-term recency effect. L. Koppenaal & M. Glanzer
5. Primacy effect or recency effect? A long-term memory test of Super Bowl commercials. C. Li
6. Consumer memory for television advertising: a field study of duration, serial position, and competition effects. R. Pieters and T. Bijmolt