Stim. Generalization
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Stimulus Generalization and Stimulus Discrimination

by

Kathy Luker


Introduction

Stimulus generalization and stimulus discrimination is truly a mouthful. Stimulus generalization (often referred to as the "rub-off effect") means the more similar two stimuli are, the more likely a person is to respond to them as if they were the same stimulus. (www.bhc.edu) For example, a green traffic light tells the driver when to drive on through an intersection. Not all green lights have exactly the same green colors; yet, we react to them in the exact same way.

In stimulus discrimination, the reverse is true. Stimulus discrimination refers to a situation in which we react differently to two or more stimuli. Keeping with traffic lights as an example, we would push down on the accelerator when the light is green, but put on the brakes when the light turns red. Unless we are colorblind, we can clearly discriminate between the two colors. (Human Behavior)

Stimulus generalization and stimulus discrimination are very important to the field of consumer behavior and to practitioners in marketing due to the fact that both occur with classical and operant conditioning. Both these conditions deal with behaviors and how we react to stimuli. First described and interpreted by Pavlov (1927) using classical conditioning, stimulus generalization has been studied extensively by Mostofsky (1965). Skinner has also done extensive research on stimulus discrimination. (Stimulus Generalization)
Stimulus generalization does not need to be the same stimulus to generate a similar reaction. Everyday, consumers generalize among product categories. Stimulus discrimination creates real associations. Rule of thumb: the longer the time of learning, the greater the product association and the more consumers will discriminate (sait.ab.ca). This means the more history we have with a product, the more we, as consumers, will discriminate.

 

Explanation of the topic

Stimulus generalization includes for a learned association between a given stimulus and response, a very similar stimulus may elicit the same response. The more similar the two stimuli, the more likely this new stimulus will elicit the learned response. (www.business.sc.edu)

For example, Pepsi and Coke are very similar causing consumers to react to them similarly. Areas of application in marketing are brand name, advertising, and product packaging. Stimulus discrimination is when the organism learns to make a response to a given stimulus, but avoids making the same response to a similar stimulus. Going back to Pepsi and Coke, packaging and trademarks allow us to discriminate between products and discriminate when purchasing.
Classical and operant conditioning share many of the same basic principles and procedures. For example, Kimble (1961) has pointed out that the basic principles of acquisition, extinction, spontaneous recovery, and stimulus generalization is common to both classical and operant conditioning (www.dushkin.com). Stimulus generalization occurs when a response is uniformly rewarded in many conditions and environments. For example, if a child is encouraged in their environment to be aggressive both at home and at school, they will develop general aggressive tendencies. In stimulus discrimination indicates when an operant response will or will not have favorable consequences. For example, we learn to belch in our own rooms at home but not in the presence of our teachers (www.psych.nwu.edu)


A consumer who learns that Nestles' Crunch candy bars taste good and therefore assumes that their new Nestles' Nesquik chocolate drink will also taste good has engaged in stimulus generalization. At some point, stimulus generalization becomes dysfunctional because less and less similar stimuli are still being grouped together. At this point, consumers must begin to be able to differentiate among the stimuli. This process refers to stimulus discrimination, the process of learning to respond differently to similar but very distinct stimuli. (Marketing Management)

A test was run similar to the original Pavlovian studies.  The issue: when a dog is conditioned to responds to a particular conditional stimulus (CS), how will the dog respond to similar (generalizable) stimuli? 

A somewhat larger bell will produce a lower but similar tone when compared to the original bell. A somewhat smaller bell will have a somewhat higher tone. How will the dog respond to the larger, original, and smaller bells? Similar stimuli with tones above or below the tone of the original still give the conditioned response, but to a lesser degree. This is sometimes called "just noticeable difference" (jnd) which indicates that some stimuli are just not different enough for us to notice a difference. In stimulus generalization the dog or subject must clearly see the stimuli as different before reacting to them differently. (www.science.wayne.edu)

Another example was an experiment done on rabbits by Liu, 1971. Rabbits had been conditioned to blink their eyes to a particular tone with a frequency of 1200 Hz (that is, a pitch slightly more than two octaves above middle C). Presenting a brief puff of air to the eye immediately after the tone had been sounded produced conditioning. When the rabbits were tested later, the largest number of conditioned responses was produced by the original tone, 1200 Hz. However, other tones produced some conditioned responses as well. For instance, a tone of 800 Hz (3 notes lower on the piano) produced a substantial response rate, and even a tone of 400 Hz (11 notes lower on the piano) produced some conditioned responses. (Marketing Management)

Stimulus generalization is useful, both for animals and for humans. After all, classical conditioning involves learning predictive relationships. Our learning would be limited if we never generalized beyond the exact same conditioned stimulus that was originally presented. Instead, generalization allows us to predict what is likely to happen in new situations. (Marketing Management) Suppose a child eats catfish, and the proteins in the catfish produce a strong allergic reaction. The child passes out, has difficulty breathing, and must be brought to the hospital emergency room. Learning should generalize to other fish that look like catfish, in order to avoid further life-threatening episodes.

STIMULUS GENERALIZATION AND MARKETING

Learning theory teaches marketers that they can build up demand for a product by associating it with strong drives which are strong internal stimulus impelling action, using motivating cues which are minor stimuli that determine when, where, and how a person responds, and providing positive reinforcement. A new company can enter the market by appealing to the same drives that competitors use and providing similar cue configurations because buyers are more likely to transfer loyalty to similar brands (generalization). Or the company might design its brands to appeal to a different set of drives and offer strong cue inducements to switch (discrimination). (Marketing Management)

The issue of stimulus generalization has relevance within a marketing context in two basic areas (Till, 2000). Stimulus generalization relates to brand extensions and private-label marketing strategies.

BRAND EXTENSION

One marketing area in which stimulus generalization is applied is brand/line extension. Brand/line extension remains an enduring component of the brand-management landscape (Berthon, Hulbert, & Pitt, 1999), as it offers a number of possible benefits, including reducing the risk of new product introductions and generating goodwill for the extension. Not all extensions are favorably viewed by the financial community or are without risk. Research on brand and line extension has focused on factors that drive successful extensions. Such factors include brand attitude and brand familiarity (Lane & Jacobson, 1995), brand quality, difficulty of making the extended brand, and perceived fit between the parent and extension brand, entry timing of extension, and support for the extension. (Till, 2000)

Stimulus generalization in classical conditioning provides one possible explanation. Indeed, stimulus generalization as a mechanism for positive affect transfer from parent to extended brand seems particularly relevant as the similarity of the parent brand to the new brand is a factor in the success of the new brand extension (Loken & John, 1993). "That greater perceived similarity between the current and new products leads to a greater transfer of positive or negative affect to the new product." (Broniarczyk and Alba). Conditioning, through the process of stimulus generalization, is one mechanism that can account for this transfer. (Till, 2000)

PRIVATE-LABEL MARKETING

Private label brands are an important factor in many grocery product categories. Private-label products attempt to mimic the packaging of leading national brands. Superficial packaging similarities between private-label and national brands may certainly result in some consumer confusion at point of purchase, leading to the inattentive shopper picking up the private-label brand by mistake. Private-label imitation of national brands may lead, through stimulus generalization, to the positive attitude toward the leading national brand transferring to the private-label brand. (Till, 2000)

For example, a study was done (Till, 1998) to examine stimulus generalization with marketing (brand) stimuli. A fictitious brand of mouthwash was tested. Sixty undergraduate students participated in this conditioning study. Proper classical conditioning control procedures were used. Evidence from this preliminary investigation suggests that conditioned evaluative responses to a brand can transfer via stimulus generalization. Specifically, some evidence for stimulus generalization was found for a similar brand in the same product category as the conditional stimulus brand and for the same brand name in a different product category. (Psychology & Marketing)

 

Examples

Suppose you buy an IBM computer. If your experience is rewarding, your response to computers and IBM will be positively reinforced. Later on, when you want to buy a printer, you may assume that because IBM makes good computers, IBM also makes good printers. In other words, you generalize your response to similar stimuli. A countertendency to generalization is discrimination. Discrimination means that the person has learned to recognize differences in sets of similar stimuli and can adjust response accordingly. (Encyclopedia of Human Behavior)

For example, suppose the first time you walked into Dr. Drea's Consumer Behavior class, you did not have a history with the class, yet you had certain responses to the environment. This was because there was much in common with previous classes you've been in, and you responded similarly to components of the class that were like previous classes. Eventually, you will refine your responses to the stimuli associated with this course, but your initial responses are an example of stimulus generalization. So, resemblance is another way that new reflexes can be developed. Like other parts of conditioning, stimulus generalization is adaptive-we don't need to learn everything all over again every time there's some change in the environment. (www.users.csbsju.edu)

It is easy to see how stimulus generalization could be carried too far. If people generalized to every new stimulus that somewhat resembled the conditioned stimulus, they would often react inappropriately. Therefore, people need to differentiate between similar stimuli, through stimulus discrimination. For example, a person who is allergic to fish that has backbones and fins must learn that he or she is not allergic to shellfish. Thus, stimulus generalization and stimulus discrimination work together. Stimulus generalization ensures that we expand our learning beyond the immediate conditioned stimulus. However, stimulus discrimination operates to guarantee that we do not generalize too broadly or inappropriately. (Marketing Management)

Conclusion

We rarely encounter the exact same situation twice. There's always some change in the environment. Usually, this new environment has some physical resemblance to an environment with which we have some history. The some is the crucial element-the more similar the new environment is to something we already know, the more we will respond in a similar way. Brand extensions and private-label marketing are two basic areas of stimulus generalization. A new company, using stimulus generalization, can enter the market by appealing to the same drives that competitors use and providing similar cue configurations because buyers are more likely to transfer loyalty to similar brands.

Stimulus discrimination is a countertendency to generalization. Discrimination is our ability to adjust to learned differences in sets of similar stimuli and respond accordingly. A company might design its brands to appeal to a different set of drives and offer strong cue inducements to switch brands. Stimulus generalization and stimulus discrimination are very important to the field of consumer behavior due to the fact that both occur with classical and operant conditioning.

 

Test for Understanding

1. Stimulus generalization is all of the following BUT:
(a) occurs with classical conditioning
(b) the more similar two stimuli are, the more likely the individual is to respond to them as if they were the same stimulus
(c) occurs with operant conditioning
(d) the more similar two stimuli are, the more like the individual is to respond to them as if they were not the same stimulus

2. Stimulus discrimination is:
(a) situation in which an organism reacts similarly to two or more stimuli
(b) situation in which an organism reacts differently to two or more stimuli
(c) situation in which an organism reacts differently to one stimuli
(d) situation in which an organism reacts similarly to one stimuli

3. An example of stimulus generalization would be:
(a) our dog recognizes our headlights from the neighbors
(b) our dog sees headlights, thinks we've come home and all headlights mean we are home
(c) our dog recognizes headlights and thinks it is dark
(d) our dog see headlights and runs to his dog house

4. Two basic areas of stimulus generalization and marketing studied by Till are:
(a) brand quality and reinforcement
(b) brand quality and brand extension
(c) brand extension and private-label marketing
(d) reinforcement and private-label marketing

5. One mechanism for positive affect transfer from parent to extended brand is:
(a) brand extension
(b) stimulus discrimination
(c) motivating cues
(d) stimulus generalization

Answers are at the end of this tutorial.

Relevant Web Sites


1. http://www.parmly.luc.edu/parmly/stimgendata (2001, March) Loyola University-Chicago,
"Stimulus Generalization and the Sense of Hearing in Goldfish"
2. http://www.science.wayne.edu/~wpoff/cor/mem/condgenl.html (3/20/01) Wayne State University, "HyperText Psychology-Memory/Conditional/generalization"
3. http://www.bhc.edu/EastCampus/leeb/psy101 (3/19/01) Black Hawk College, "Stimulus Generalization"
4. http://www.users.csbsju.edu/ (3/28/01) College of Saint Benedict, Saint John's University, "A Little More on Pavlovian Conditioning: Extensions of the Basic Paradigm"
5. http://www.psych.nwu.edu/~garea/behavconep.html (3/31/01) Northwestern University, "An Outline of Behaviorism"
6. http://www.sait.ab.ca/mktg210/market (3/31/01) Southern Alberta Institute of Technology, Canada, "Stimulus Discrimination"
7. http://www.business.sc.edu/fall97/mktg758conditioning.html (3/31/01) University of South Carolina, "Classical and Operant Conditioning"


References


1. Encyclopedia of Human Behavior, Volume 3 (J-P), Academic Press, Operant Learning, pp. 355.
2. Kotler, Philip (2000) Marketing Management, The Millennium Edition, (6) p. 174-179 Prentice-Hall, Upper Saddle River, NJ
3. Mostofsksy, D. (1965) Stimulus Generalization, pp.133, Stanford University Press, Stanford, CA.
4. Till, Brian D. (2000) "Stimulus Generalization in Classical Conditioning: An Initial Investigation and Extension," Psychology & Marketing, 17 (1), 55-73.





Test for Understanding Answers

1. d. 2. b. 3. b. 4. c. 5. d.