Chem. Percept. (2011) 4:1–8 DOI 10.1007/s12078-010-9082-0

Incongruent Contextual Information Intrudes on Short-term Olfactory Memory Naomi L. Streeter & Theresa L. White

Received: 19 July 2010 / Accepted: 24 November 2010 / Published online: 4 December 2010 # Springer Science+Business Media, LLC 2010

Abstract Both name and source information provide a context for the perceptual evaluation of odorants (Herz, J Exp Psychol 132(4): 595–606, 2003) that may also affect memory (Lyman and McDaniel, J Exp Psychol 16(4): 656– 664, 1986). The current study asked whether appropriate information about the context in which an odor source is found would affect short-term memory for the odor. Fiftyfour participants were presented with pairs of olfactory stimuli and visual contextual information that either matched each other or did not. There were two types of visual stimuli, either a pictorial representation of a contextual location for an odor source or a written representation of the name of that location. Stimulus presentation was followed by a verbal interference task (Peterson and Peterson, J Exp Psychol 58: 193–198, 1959). A recognition test for the olfactory stimuli conducted immediately afterwards revealed that participants who had been presented with visual representations of non-matching odor source contexts were more likely to falsely remember odors appropriate to the visual context. These findings suggest that participants either relied heavily on encoding of the visually presented source contextual information, to the detriment of memory, for olfactory stimuli or suffered from the semantic-based memory error of misattribution. Keywords Cognition . Human . Memory . Olfaction . Verbal influences N. L. Streeter Department of Education, Le Moyne College, Syracuse, NY, USA T. L. White (*) Department of Psychology, Le Moyne College, Syracuse, NY, USA e-mail: [email protected] T. L. White SUNY Upstate Medical University in Syracuse, Syracuse, NY, USA

Introduction Odors are cognitively closely associated with the source object from which they are emitted, and odors are typically named for their sources (Dubois and Rouby 2002). When information about a source object, either verbal or pictorial, is presented with an odorant at the time of encoding, olfactory memory can be influenced. For example, participants instructed to elaborate odorants by naming and providing a definition of the odor source performed better on a subsequent olfactory recognition test than subjects not advised to use any particular elaboration technique (Lyman and McDaniel 1986). In addition, the presentation of a visual representation of an odor’s source improved memory for the odor a week later (Lyman and McDaniel 1990). Whether or not source information assists odor memory is related to how well the information matches the odors to be remembered. Labeling with a common veridical or familiar name during initial stimulus presentation can improve recognition performance (Rabin and Cain 1984) while poor labels can lead to a deterioration of performance on a subsequent olfactory recognition task (Engen and Ross 1973). Although the close association between odors and their sources undoubtedly influences olfactory memory, an odor’s source is a small portion of the context that surrounds an odor. Beliefs about an odor’s health properties (Dalton et al. 1997), the emotional valence of the situation in which the odor is experienced (Epple and Herz 1999; Kirk-Smith et al. 1983), and beliefs about the origins of an odor (Distel and Hudson 2001; Herz 2003) are all parts of the context that influences odor perception. The location in which an odor is experienced also forms a portion of the context surrounding odors, in that odors both emanate from a source object and are also found ambiently in places where the exact source of the odor is not clear. For example, many bakeries smell of bread, though the loaf itself may not be readily observed. Few studies have examined the quality of the relationship between odors

2

and their contextual source locations. It is not yet clear, for example, whether associations between a source location and an odor are formed implicitly (Degel and Köster 1999) or explicitly (Takahashi 2003), but the association seems to be more susceptible to age-related impairments than other types of memory (Gilbert et al. 2006, 2008). Neither has the question of whether contextual source information may assist or impair odor memory yet been addressed. The present experiment asked whether information about a location where an odor might be found, rather than a veridical representation of the source, could influence odor memory. It was hypothesized that, like veridical name information (Rabin and Cain 1984), appropriate contextual information about an odor source location would be an aid to olfactory memory while inappropriate source location information would impair it. Participants in the present study were presented with odors paired with either verbal or pictorial representations of locations where odorants could be found. The locations represented were either appropriate (e.g., picture of a new car with the smell of leather) or inappropriate (e.g., picture of a bakery with the smell of leather) to the smell presented. Participants were explicitly asked to remember both the location and the odor, but were only tested on olfactory recognition. If source location information can affect olfactory memory, then participants should show more accurate recognition memory when the visual contextual source information is appropriate than when it is not. The design of the present experiment also allowed the examination of errors in memory performance that could reveal information about sensory systems in a cross-modal memory task (e.g., Cain and Potts 1996). Because the contextual source location information was presented visually, a sensory system which is highly salient for humans, this information might be given priority over the perceptual olfactory information in terms of contributing to the memory trace. To test this possibility, some distracter odorants in the recognition task were chosen so as to match the inappropriate visual stimuli. If visual source location information takes priority over olfactory information during encoding, then people in the incongruent visual stimuli groups should mistake these inappropriate distracter odorants for the target odorants during the recognition task.

Materials and Methods Participants Fifty-four people (41 females and 13 males; mean (M) age= 19.8 years, standard deviation (SD)=2.8 years) volunteered to participate in the experiment. All participants were offered course credit in a Psychology class in exchange for participation and were treated in accordance with the ethical

Chem. Percept. (2011) 4:1–8

principles set forth by the American Psychological Association (2009). This experiment was approved by the Institutional Review Board of Le Moyne College. All participants were screened after the experiment using the Brief Smell Identification Test (B-SIT; Sensonics, Inc.) to ensure a normal sense of smell. Data from participants with four or more incorrect answers on the B-SIT were to be excluded from analysis, but all participants, regardless of olfactory ability, received credit for participating in the experiment. Participants were thoroughly debriefed at the experiment’s end. Materials Selection of Stimuli A pilot study, using eight people (one man and seven women; M age=22.1 years, SD=5.5 years) who did not participate in the main experiment, was performed to evaluate the perceived appropriateness (or “fit”) between possible combinations of 16 pictures of odor source contextual locations, 16 written representations of the names of the odor source contextual locations, and 24 odorants. On each trial, participants were asked to rate how well two stimuli from the three types (pictures, odors, names) fit each other using an unstructured line scale, with anchors of “Do Not Match at All” at 0 and “Perfect Match” at 5.5 in. Of the 56 stimuli in the pilot experiment, 18 odors (see Table 1) and 24 visual stimuli (12 pictures and 12 words; see Fig. 1) were selected for inclusion in the main experiment since their relationships (see below) displayed greater ratings of fit (more than 2.75 in.). Relationship of Visual and Olfactory Materials All of the stimuli included in the main experiment were associated with each other. Six of the odorants (targets) had corresponding visual stimuli that conveyed either appropriate or inappropriate contextual source location information (see Fig. 1). An appropriate visual stimulus named or depicted a place where the target odorant might be found, while an inappropriate visual stimulus named or depicted a location that would be unlikely to contain the target odorant. For example, the target odor “soap” had appropriate visual stimuli (picture and word) that were representations of “bathroom” and inappropriate visual stimuli (picture and word) that were representations of “grill”. Each target odor was also associated with two distracter odorants (see Table 1), one that was typically found in the location depicted by the inappropriate visual stimuli (inappropriate distracter) and the other that was typically found in the location depicted by the appropriate visual stimuli (appropriate distracter). So, to continue the

Chem. Percept. (2011) 4:1–8

3

Table 1 Odorants (manufacturers) Target odorant

Bleach (Clorox) Coffee (Maxwell House, Rich Original Blend) Leather (International Flavors & Fragrance) Peanut butter (Price Chopper) Soap (Dove, “white”) Pine (International Flavors & Fragrance)

Distracter odorants Appropriate distracter odorant (congruent to appropriate visual stimuli)

Inappropriate distracter odorant (congruent to inappropriate visual stimuli)

Detergent (All Small & Mighty) Pasta sauce (Ragú Traditional) Rubber (Elmer’s Rubber Cement) Mustard (French’s) Bathroom cleaner (Fantastik) Peppermint extract (McCormick)

Rosemary (Dried Herb) Perm solution (Jheri Redding) Frosting (Smacker’s Vanilla Frosting Lip Sparkler) Manure (Civet, International Flavors & Fragrances) Smoke (Colgin Natural Hickory Liquid Smoke) Baby Powder (International Flavors & Fragrance)

example above, if the participant were in the incongruent word group, so that the smell of soap (target) and the word “grill” (inappropriate visual stimulus) were presented at encoding, hickory smoke would be an inappropriate distracter odorant. The smell of hickory smoke is congruent to the source location information “grill”, although the odor of hickory smoke is nothing like that of soap. In contrast, if the smell of soap (target) had been presented with a picture of a bathroom (appropriate visual stimuli), then an appropriate distracter odorant would be the smell of bathroom cleaner, which is consistent with the source location “bathroom” but smells differently than the odor of soap. Olfactory Stimuli The 18 olfactory stimuli selected for inclusion in the main experiment and their manufacturers are shown in Table 1. The odorants were held in 40 ml amber vials, and were obtained from commercially available sources at undiluted strengths. The amber vials containing the olfactory stimuli were presented to participants in two different ways: via odor wheel (in the presentation/encoding phase of the experiment) and manually (at test). The odor wheel (White et al. 1998) is a stainless steel device that can hold up to 15 glass vials in a circular fashion, such that when a lever is pushed, the wheel rotates from one smell to the next. The wheel has a small opening over which a participant’s nose may be placed in order to smell the odorant beneath it. Visual Stimuli The pictures and names that were selected in the pilot for inclusion in the main experiment were related such that the complex visual scenes in the pictures reflected images evoked by the verbal labels. So, the word “bathroom” was included in the verbal condition and a picture of a bathroom was included in the pictorial condition. It is important to note that the odor source object (e.g., the bar of soap for the target

“soap” smell) was not depicted directly by either the pictorial or the verbal visual stimuli. All verbal labels were presented via PowerPoint presentation in Arial 80 pt font, centered on a 15-in. computer screen. All complex pictorial scenes were 4.8×6.4 in. and centered on a 15-in. computer screen. Response Booklet The participants’ recognition responses were collected in 12-page booklets containing a separate page for response to each test odorant. Each page contained “yes” and “no” checkboxes to indicate whether the odorant presented in the recognition test had been previously presented, along with a 5-point Likert scale to rate confidence in the response, with a “1” being “Not Sure” and 5 being “Very Sure.” Design This experiment was a factorial 2×2×3 mixed model design, with type of visual stimuli (picture, word) and visual stimulus matching (appropriate and inappropriate) as between-subjects variables. The within-subject variable was the type of olfactory test stimulus (target, distracter matching appropriate visual stimulus, and distracter matching inappropriate visual stimulus). Procedure Participants were randomly assigned to one of four groups that differed in terms of the visual stimuli that accompanied target odorant presentation: Congruent words, incongruent words, congruent pictures, or incongruent pictures. In the congruent words group, the visual stimuli were the names of places where the target odorants might be found. In the incongruent words group, the visual stimuli were the names of places unlikely to contain the target odorant. The visual stimuli for the congruent picture group were complex visual scenes depicting places where target odorants would typically be found. The visual stimuli for the incongruent

4

Chem. Percept. (2011) 4:1–8

Target Odorant

Appropriate Visual Stimuli

Inappropriate Visual Stimuli

Bleach

Laundry

Meadow

Coffee

Kitchen

Salon

Leather

New car

Bakery

Cafeteria

Farm

Soap

Bathroom

Grill

Pine

Christmas

Nursery

Peanut butter

Fig. 1 Stimuli given during initial presentation: target odorants, pictures, and verbal labels

picture group were scenes of places that would be unlikely to contain target odorants. All participants were told that they would be presented with two types of stimuli (olfactory and visual) to

remember, and that it would be important to attend to both types of stimuli. Participants were also cautioned not to attempt to name (in the case of groups seeing pictures) or visualize (in the case of groups seeing names) any of the

Chem. Percept. (2011) 4:1–8

stimuli. Although the participants were told their memory would be tested after an interference task, they were not instructed as to which stimuli (olfactory or visual) would comprise the test. Each participant was presented with six target odorants paired with six visual stimuli (which differed by group). All participants were seated at a computer with the odor wheel (White et al. 1998) containing the target smells directly in front of them. The experimenter rotated the smells with the lever of the odor wheel in a manner that was time locked to the presentation of visual stimuli on the computer screen in the presentation portion of the experiment. Each of the six odorant-visual stimulus pairs was presented for 5 s, with a 1 s inter-stimulus interval. Each participant received a different random ordering of the odorant-visual stimulus pairs. After inspecting all six odorant-visual stimulus pairs, participants performed an interference task (Peterson and Peterson 1959) in order to limit verbal encoding. For the interference task, the investigator provided the participant with an arbitrary number that had been selected prior to the participant’s arrival. The participant was asked to count backwards in increments of three (aloud) from the preselected number for 1 min. Following the interference task, participants attempted to recognize the six target odorants which were intermingled with six distracter odorants (see Fig. 2). The 12 recognition test olfactory stimuli were presented one at a time in a unique randomized order for each participant. Three of the six olfactory distracters in the recognition test olfactory stimuli were selected randomly from a set of six appropriate distracter odorants, while the other three were randomly selected from a set of six inappropriate distracter odorants Fig. 2 Graphic representation of experimental design. Note: Regardless of group membership for stimulus inspection, each participant was tested with a random ordering of odorants, comprised of targets as well as both appropriate and inappropriate distracter odorants. Appropriate distracters were congruent to appropriate visual stimuli while the inappropriate distracter odorants were congruent to the inappropriate visual stimuli

5

(see Table 1). Participants were able to inspect each test odorant for as long as they liked, and were asked to report whether they had encountered the odorant previously in the experiment by checking “yes” or “no” in the test booklet, and then rating their confidence in their memory decisions on a scale of 1 to 5.

Results The data from seven participants was eliminated from the data set due to low B-SIT scores, leaving 47 for the present analysis. Thus, each group contained 12 participants, with the exception of the inappropriate names group, which contained 11 participants. As the experiment essentially formed a yes–no experiment with confidence ratings, the data from both the yes/no judgments and confidence ratings were transformed into A’ (similarly to Macmillan and Creelman 1991), and subjected to a 2×2 ANOVA (type of visual stimuli (picture, word)× visual stimulus relationship to odorant (appropriate, inappropriate)) for a test of the primary hypothesis. In this primary analysis, no significant main effects were detected for either type of visual stimulus [F (1, 43)=0.001; p=0.98] or visual stimulus relationship to odorant [F (1, 43)=1.183; p=0.28]. Neither was the interaction of these two variables significant [F (1, 43)=0.249; p=0.62]. Although the analysis above allowed examination of the primary hypothesis regarding the congruency of olfactory and visual information, it did not allow the secondary hypothesis concerning the interaction of congruency of visual information and type of distracter odorant to be examined. Consequently, a

6

measure (D) was constructed for each subject that by multiplying each distracter confidence rating by −1 if it had been a false alarm (“yes” response) and +1 if it had been a correct rejection (“no” response). The sum of these weighted confidence ratings was taken for each type of distracter, and then the sum for the subject’s inappropriate distracters was then subtracted from the appropriate distracters to form the measure, D. A positive D score would indicate that more correct rejections with higher confidence ratings had been obtained for appropriate distracters than inappropriate distracters, while a negative D score would indicate the opposite. The planned comparison of congruence and distracter type showed that the D score nominally differed based on congruence, t (43)=1.89; p=0.03, one-tailed (congruent pictures—M=−1.5, SD=10.88; incongruent pictures—M= 4.92, SD=8.08; congruent words—M=−2.41, SD=10.12; and incongruent words—M=2.27, SD =11.02). This is illustrated in Fig. 3, where the average percentage of false alarms is given for each type of distracter by group. Thus, participants were more likely to erroneously respond that odorants corresponding to the visual stimuli encountered previously had been presented (false alarm).

Discussion The goal of this study was to explore the effects of contextual odor source location information available during encoding on olfactory memory. Odor recognition

Fig. 3 Mean percentage of false alarms (+SE) for distracter olfactory stimuli at memory test as a function of appropriateness and type of visual stimuli presented with target odorants at encoding

Chem. Percept. (2011) 4:1–8

was explored across four groups of participants to determine whether accuracy could be influenced by the concurrent presentation of visual stimuli that varied in the appropriateness of the source location information to the target odorant. Participants were given a recognition test that included three types of recognition stimuli: target odorants, distracter odorants that matched appropriate visual stimuli, and distracter odorants that matched inappropriate visual stimuli. It was hypothesized that matching visual contextual information about an odorant source’s location, either via pictures or verbal labels, would enhance accuracy, while inappropriate visual information would impair it. Contrary to the primary hypothesis, the results did not demonstrate a significant main effect of the match of visual stimulus to the target odorant, thus matching verbal labels for olfactory stimuli did not enhance the odor recognition ability of participants. In contrast to other aspects of context such as names or emotion (e.g., Jehl et al. 1997; Kirk-Smith et al. 1983), information about the location in which an odor is typically experienced did not enhance memory for the odor. There are several reasons that the visual source locations presented could have failed to enhance odor memory. Even though participants were told to attend to both types of stimuli, it is possible that the visual stimuli simply provided redundant semantic information, essentially a surrounding or everyday backdrop that could easily be disregarded if the overall meaning of the scene remained the same, somewhat akin to change blindness (Simons and Levin 1998). Perhaps the associations between odors and the possible source locations presented in the present experiment were not as strongly associated as one might have hoped. A loose connection between the olfactory and visual stimuli would give rise to a myriad of associations with a visually presented source location. So, unlike the close association between the odor of coffee and the picture of a cup (Degel and Köster 1999), the picture of a cafeteria might have many associations. An additional explanation is that associations between odors and their possible source locations may be weaker than associations between odors and their sources, given that any odor source may occur in multiple locations. Still another possibility is that since odors often have minimally fixed sources (Herz and von Clef 2001), strong or close associations with specific odorants may not be readily available for source locations. Odor memory was influenced in the present study by an interaction between the appropriate visual stimulus and type of recognition stimulus such that people who viewed inappropriate visual stimuli with the target odorants were more likely to misremember distracter odorants corresponding to the visual stimuli as part of the target list. One reason for this finding may be that the participants were relying so heavily on the visual information that they

Chem. Percept. (2011) 4:1–8

failed to adequately encode the olfactory information, resulting in a decrease in recognition accuracy at test. Despite the instructions, it is possible that participants may have relied on the visual stimuli rather than the olfactory stimuli, and thus were led astray by non-matching visual information. However, it is also possible that the ability of inappropriate visual information to mislead participants into falsely indicating that odors consistent with that information had been presented may be due to a memory error involving misattribution of source (Schacter and Dodson 2001). If both olfactory and visual information were represented mentally in a sensory-free manner, it would be difficult for a participant to determine at test whether a target odorant or a distracter odorant that matched a visual stimulus had been initially presented. This idea is supported by at least one study (Pauli et al. 1999) in which olfaction acted as a primer, influencing the naming speed of the colored ink of words related to olfaction and suggesting that the point of intersection of the pathways of different sensory systems converge at some higher sensory-free zone. Since the instructions in the present experiment did not explicitly indicate which type of stimuli would be included in the memory test, they potentially encouraged a misattribution memory error. Still another explanation for these findings, however, is that increased task complexity in the non-matching conditions decreased encoding ability, thus impairing later memory function (Perkins and Cook 1990).

Conclusions While the experimental context is relevant to encoding in odor memory, the present research does not support the idea that the presence of appropriate source location information improves odor memory. However, some evidence was presented that the presence of accompanying visual information could mislead participants into false recognition. One interpretation of these findings suggests that olfactory information, similar to other types of information, may be subject to memory error of misattribution. This olfactory memory error could reflect a tendency toward recalling the “gist” of a situation rather than the details, presumably in an effort to facilitate transfer and generalization across memory systems (Schacter and Dodson 2001) and to minimize memory capacity requirements (Anderson and Schooler 1991). However, additional research in this area should be performed to provide further support for these conclusions. Acknowledgments This work was supported by a grant from the Le Moyne Student Research Fund (N.S.) and presented in partial fulfillment of Bachelor of Arts, Honors requirements at Le Moyne

7 College. This project was presented in poster form at the XXIX Meeting of the Association for Chemoreception Sciences (AChemS) in Sarasota, FL, April 25–29, 2007. The authors would like to thank Dr. Paul Sheehe for his assistance with the design of the study and his thoughts on the results section of this paper. The authors would also like to thank International Flavors and Fragrances for providing some of the olfactory stimuli.

References American Psychological Association (2009) Publication manual of the american psychological association, Sixthth edn. American Psychological Association (APA), Washington Anderson JR, Schooler LJ (1991) Reflections of the environment in memory. Psychol Sci 2:396–408 Cain WS, Potts BC (1996) Switch and bait: probing the discriminative basis of odor identification via recognition memory. Chem Senses 21:35–44 Dalton P, Wysocki CJ, Brody MJ, Lawley HJ (1997) The influence of cognitive bias on the perceived odor, irritation and health symptoms from chemical exposure. Int Arch Occup Environ Health 69(6):407–417 Degel J, Köster EP (1999) Odors: implicit memory and performance effects. Chem Senses 24:317–325 Distel H, Hudson R (2001) Judgement of odor intensity is influenced by subjects’ knowledge of the odor source. Chem Senses 26:247–251 Dubois D, Rouby C (2002) Veridical names and categories for odors. Cambridge University Press, Cambridge Engen T, Ross B (1973) Long term memory of odors with and without verbal descriptions. J Exp Psychol 100:221–227 Epple G, Herz RS (1999) Ambient odors associated to failure influence cognitive performance in children. Dev Psychobiol 35 (2):103–107 Gilbert PE, Pirogovsky E, Ferdon S, Murphy C (2006) The effects of normal aging on source memory for odors. J Gerontol B 61:58– 60 Gilbert PE, Pirogovsky E, Ferdon S, Brushfield AM, Murphy C (2008) Differential effects of normal aging on memory for odorplace and object-place associations. Exp Aging Res 34(4):437– 452 Herz RS (2003) The effect of verbal context on olfactory perception. J Exp Psychol 132(4):595–606 Herz RS, von Clef J (2001) The influence of verbal labeling on the perception of odors: evidence for olfactory illusions? Perception 30:381–391 Jehl C, Royet JP, Holley A (1997) Role of verbal encoding in shortand long-term odor recognition. Percept Psychophys 59(1):100– 110 Kirk-Smith MD, Van Toller C, Dodd GH (1983) Unconscious odour conditioning in human subjects. Biol Psychol 17:221–231 Lyman BJ, McDaniel MA (1986) Effects of encoding strategy on long-term memory for odors. Q J Exp Psychol 38:753–765 Lyman BJ, McDaniel MA (1990) Memory for odors and odor names: modalities of elaboration and imagery. J Exp Psychol 16(4):656– 664 Macmillan NA, Creelman CD (1991) Detection theory: a user’s guide. Cambridge University Press, New York Pauli P, Bourne LE Jr, Diekmann H, Birbaumer N (1999) Crossmodality priming between odors and odor-congruent words. Am J Psychol 112(2):175–186 Perkins J, Cook NM (1990) Recognition and recall of odours: the effects of suppressing visual and verbal encoding processes. Br J Psychol 81:221–226

8 Peterson LR, Peterson M (1959) Short-term retention of individual verbal items. J Exp Psychol 58:193–198 Rabin MD, Cain WS (1984) Odor recognition: familiarity, identifiability, and encoding consistency. J Exp Psychol Learn Mem Cogn 10:316–325 Schacter DL, Dodson CS (2001) Misattribution, false recognition, and the sins of memory. Phil Trans R Soc Lond B 356:1385–1393

Chem. Percept. (2011) 4:1–8 Simons DJ, Levin DT (1998) Failure to detect changes to people during a real-world interaction. Psychon Bull Rev 5(4):644–649 Takahashi M (2003) Recognition of odors and identification of sources. Am J Psychol 116(4):527–542 White TL, Hornung DE, Kurtz DB, Treisman M, Sheehe P (1998) Phonological and perceptual components of short-term memory for odors. Am J Psychol 111(3):411–434