Images in Chemistry Roberta W. Kleinman,' Henry C. Grlffin,z and N. Konigsberg Kemer University of Michigan. Ann Arbor, MI 48109 Concern for difficulties students encounter in learning chemical conrept;i must be universal among chemistry instrurtors, but relatively few instructors approach this problem in an analvtiral manner. Reif I 1 I describes learnine and teaching as a transformation process in which the &dent goes from initial state S, to a final state SEof improved intellect. He lists four unknowns which confront a systematic study of the process: What are the characteristicsof S:? , What are rherharncteriatird uf St'' f hat isa path from S to.qi? \!'hat pmcriee will implement t h e process? ~
+
~~~
Although Reif's association with the Graduate Group in Science and Mathematics Education a t Berkeley gives him an interdisciplinary perspective, his article ( I ) emphasizes learning and teaching physics. Significant progress toward a svstematic approach to learnine chemistrv has been made. For examp1e;~erron(2) studiedstudent characteristics and found that about half of entering college students have not reached the "formal" reasoning level required for understanding some chemistry concepts. Wiseman (3) found that the path to understanding chemistry involves more than formal reasoning. We suspected that images play an important but little recognized role in "doing" chemistry. There is certainly little explicit attention to relations among the types of chemical images and to transitions between images and other forms of knowledge. For example, in discussing molecular symmetries one of us drew a representation of bromobenzene (with bromine identified as "Br") on the board and declared "a plane of symmetry is perpendicular to the ring and passes through the 'b r' ". At the end of the class hour a student denied &e molecule had the purported symmetry because "b" Z "I". This range possibilities for misrepre. of . sentation is suggested in Figure 1. We divided our inquiry into two stages. First we sought to determine the importance of images to experienced chemists-we sought to characterize the final state with respect to images. Anecdotal information from departmental and divisional seminars supported our suspicions that visual (and probably other types) of images are quite important. Our sample was biased in that our subjects were all involved in teaching as well as research. However, the evidence seemed sufficiently strong that we concentrated on the second phase: determining the nature of images among learners, with particular attention to correlations with level of learning. Along the way we discovered there is much more to images and their study than we initially realized. In brief, types of images (4) correspond to sensory or "input" channels-;ision, audition, smell, taste, and kinesthesia (gross muscle and nerve response). Any mental image can he triggered by any sense. When we hear the hissing and crackling of logs hurn-
Presented in part at the 8th Biennial Conference of the Division of Chemical Education at Storrs, CT. 1984. Present address: Lock Haven University. Lock Haven, PA 17745. Corresponding author.
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Figure 1. Images in the classroom.
ing in a fireplace hidden from view (auditory input), we might visualize a burning log, or smell the smoke, or even feel the heat as though we were standing in front of it. Images can be substantially voluntary. Nikola Tesla (5) claimed to he able to test proposed devices by turning them on in his imagination and bringing them back weeks later to examine them for signs of wear. Several studies (6-8) have shown that a learner creates some type of symbolic construction to code information and make i t more meaningful. An image is one such construction. Forisha ( 9.) sueeested that imaeerv " .individualizes our exnerience, gives meaning to our thoughts, and can help or hinder our ahilitv to reason. Bunelski (10) summed uo a number of studies that show thatUcomm&ication ma< fail because meanings are dependent on individual imaaerv. ~ r n h e i m(11) pointed out that diagrams &an important part of abstract thinking and that idiosvncrasies in perception can prevent connecting existing knowledge with new experience. Bodner and McDaniel (12) found a positive correlation between verbal, numerical, and spatial abilities and performance in an introductory college-level chemistry course.
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Experlrnental Method We developed a list of chemical terms that might be associated with images and designed a procedure to determine the specific images that subjects (chemists and students) associated with these terms. Key Words. The chemical terms were selected from standard, general chemistry texts. The key words were bond, energy, equilibrium, functional group, mole, orbital, rate, resonance, solubility, and spontaneous process. Professional Leuel of Interuiewees. The subjects were all volunteers and comprised three professional levels: undergraduates, graduate students, and a combined group of faculty and postdoctoral students (referred to as faculty in this study). There were ten undergraduate, eight graduate students, and three faculty. Interview Procedure. Each person listened to a short tape
that outlined.the purpose of the interview and described the procedure that would he followed, including taping the interview. Each key word representing a concept was read and shown to the subject, and the subject was given five seconds to respond before the interviewer asked whether the interviewee was ex~eriencineanv imaees. The resnonses were verbal descriptions a n z drawing; The inte&ewer interrupted a description only to ask for a clarification of a response (for example, if a person responded "K," to the key word solubility, he or she was asked to describe how solubility was experienced), or to record on the tape any body movements the subject was making. Care was taken to use language that did not suggest a particular type of imagery. Data Analysls
At the end of each interview the tape was transcribed, and the separate images for each key word were counted. For example, "Big hall of heat, light, the sun7'wascounted as one image, and "I experienced heat, I experienced light, I experienced the color yellow, I experienced explosions, I saw the sun" was counted as five images. The separate images given by each person for each concept were listed, and each image was classified according to the following categories: (1) whether the image was chemical or nonchemical, (2) whether the image was visual, kinesthetic, or auditory, and (3) the level of ahstraction of the chemical image. Level of Abstraction
Each chemical image was placed into one of the following categories, listed in order of increasing abstraction. 1. Associative (simple word association such as the letters "K,," as the only response to solubility). 2. Real (a description of a concrete or real-world exoerience such as "sun" for energy). 3. Model (a description of an abstraction such as "electron densi-
ty" for orbital).
An image was put into the least abstract category (associarive) i f (1) the person responding indicated thatthk image he or she was experiencing consisted only of words or numbers, and (2) the descri~tionthat immediatelv" followed -~~ for the ~--same concept showed essentially no greater degree of abstraction. Several of the imaees eiven for the kev word mole are good examples of the sze&on process usld to decide between the associative category and a higher degree of ahstraction. One graduate student responded to mole with ~
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~
~~
I experreneed it as a figure And what 1 see isa figure like if it was wrlttm dnwn on a blackhoard. . I see the number.. . I don't Ree any l ~ r t ~ rIaonly , see the figures
There were no other images reported by this graduate student for mole. This image was classified as an associative image. Another graduate student, who also first reported experiencing a number, went on to clarify the number as "numher of particles. . .many,multitudes, just kind of many things". This image clearly shows a higher degree of ahstraction than that reported by the first graduate student. An image was put into the real category if the image corresponded to the experience of a concrete thing or event, such as several of the images given for the key word solubility. One graduate student responded with putting salt into a beaker of water.. .I can see the beaker, pour the salt in, stir it up and you no longer see the solid but it's dissolved. An undergraduate reported two images for solubility, the first an associative image
The first thing I think of is K.,, and I think that's because we just studied it and the second real image, then I kind of like see a beaker and something dissolving in it.
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An imaee was ~ uinto t the most abstract cateeorv - (model) . if (1) numbers 07 words were further elaborated (as in the second e x a m ~ l eeiven for mole). (2) the elaboration was not simply a deseripiion of a concrete thing or event, and (3) i t involved the description of a mathematical operation or a concept that was derived from one of the accepted models used in chemistry. I t was not necessary that the description he chemically or mathematically correct. Many of the images reported for orbital were placed in the model category. One of the undergraduates reported seeing a round, I guess it would be like an atom with orbitals going around it. . .I see like a motion, orbital going around the center.
While the undergraduate was describing the image, she was also drawing the standard representation of a Bohr atom. One of the graduate students reported several related images. Again, it's the electron density and defined by boundaries.. .I think of chemical reactions, orhital overlaps, bonds ehanging.. .Visually. One faculty memher also reported several images for orbital including a spatial property where the electrons will he located. It has sharp edges because I usually associate that with, for instance, the fact that 90%ofthe electrons.. .The edees and the shaoe of the edees. They're very sharp and they're even associated wiih a given energy scale. The average numher of images per person a t each level of abstraction is reported in Tahle 1. The data in Tahle 1then were used to calculate, for each key word and each professional level, the fraction of the images a t each level of ahstraction. These fractions are shown in Figure 2. The model category for the faculty n o u p was used as the standard t o order the data; the fraition of model images for the faculty decreases from mole t o rate. There is an increase in both the level of ahstraction and in the total number of images per person in going from the undergraduates to the faculty. Not only did the faculty report more abstract images, but they also reported the greatest total number of images per person. The major changes in going from the undergraduates to the faculty are an increase in the average numher of images in the model category and a decrease in the average numher of images in the associative category. The average numher of real images per person remained relatively constant for all three groups. There does not appear to be any pattern as to which key words tend to elicit more associative, more real, or more model responses. I t is interesting to note that associative images are still reported by the faculty. The overall degrees of abstraction for the three groups is shown in Figure 3. The greatest fraction of images reported by the undergraduates are in the associative category; for the faculty, the greatest fraction are in the model category. The graduate students fall in between. They do show a greater fraction of images in the model category, hut also show a substantial fraction in the associative category. There is only asmall change in the real image category when comparing all three groups. Volume 64
Number 9
September 1987
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Table 1.
-AssociativeF'
Kev Word
-1 G1
US
F
Frequency of Images Level of Abstractiona Real 1G
11
G
Mole Orbital Func. Group Bond Spon. Proc. Energy Equilibrium Resonance Solubility Rate TOTAL'
d hpar&meoes ; i
Table 2.
& percamage of sublen. in a given goup uM desdbed at lead one Image at me given 1-1
Speclllc lmages lor Selected Key Words Number of Reports F G u
Energy heat [c] the sun [c] (running, physical motion) [c] light [c] names of energy forms [s] a specific color of light [c] an energy diagram [m] an explosion [c] (lhunderstorm) [ c ] doing work [c] the word "energy" [s] the words "mc squared [s] eiectrochsmical cells [elm] chemical reactions [slc]
Orbitals speciiic 3-Dshapes [m] electron density [m] the Bohr atom [m] (the solar system) [c] drawings of the wbltals [m] phases, signs, and lobes [m] a mathematicaldescription [m] Ieners of the OrWais [s] baliwns [c] canon balls [clml
Solubility something dissolving [el a beaker or other container [c] precipitation or something insoluble [c] the letters "k," [s] pouring or stirring [c] liquids in general [c] salt [c] water [c] specific colon of solutions [c] collisions of particles [m] solvation spheres [m] sugar [ c l
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M abstraction.
Journal of Chemical Education
Total
Figure 2. Levels of abstraction for key words.
0.6
' I
0.4
' I
raduale Students
0.2 I 0
ASSOC.
Real
Modd \
Figure 3. Levels of abshactian versus experience.
Specific Images for Selected Key Words Table 2 is a listing of most of the images given by the interviewees for three of the selected key words. T o be included in the listing an image had t o be described by a t least two people. The descriptions are not direct quotes from the transcribed tapes but paraphrases of similar images. Several of the images would not be considered chemical images; these images are given in parentheses for each key word. Nonchemical images were described for several other key words as well. The images presented for these three key words illustrate that some concepts tend to evoke more images that are real
Table 3.
Modes of Images Mode
Profeseimal Level
Undergraduate Graduate Fawltv
Visual
Kinesthetic
Auditory
1.0 1.3 1.0
1.0 1.1 1.2
0.2 0.3 0.2
or associative (energy and solubility) while other concepts tend to evoke more images that are models (orbital). What can be seenfor these three key words and is true for the other key words as well is that the specific images reported bv a majority of the faculty are often not the specific images reported by the undergraduates, even though both groups may be reporting images a t the same level of ahstraction. Again the graduate students fall in between, sometimes reporting the same specific images as the faculty (orbital) and sometimes reporting images that are closer to those of the undergraduates (solubility). Image Modes We also analyzed each image t o determine whether any particular mode of imagery was favored by the different groups. For this preliminary investigation, we limited the modes to visual, kinesthetic, and auditory. A visual image is any static or changing mental picture. The picture might be of a real object or event, such as sugar dissolving in a beaker. I t might he of a model that can he constructed in the real world, such as the model of an atomic orbital. I t might be the picture of a symbol or symbols, such as "CH3C00HXor "K,,,"or simply words or sentences. An auditory image involves hearing words or sentences or other sounds such as music, thunder, or explosions. A kinesthetic image is a sensation of movement, pressure, heat, cold, change, or other tactile sensation. The words used hv each person were analvzed to determine u,hether he or ;he used visual, kinesthehc, or auditory words in describing each mental image. Descriptive words were identified and-the number and type of representational words recorded. For example, one image reported hy one graduate student for bond was "glue . . . sticking together." The word "sticking" is a kinesthetic word. The same graduate student in resoonse t o functional zrom . said. "I can see aldehydes and ketones." he word "see" makes this a visual image. An undergraduate in response to mole said that he was "hearing six point oh two times ten to the twenty-third . . . ". The word "hearing" indicates that this is an auditory image. The average number of visual, kinesthetic, and auditory words used in describing a single image was determined for-each person and averaged ov& all the interviewees in each group. The results are reported in Tahle 3. The data show that all three groups tend to use visual and kinesthetic words in reporting images. Auditory words are much less common. The only exception was one graduate teaching assistant who had received an undergraduate degree in chemistry but was a graduate student in the law school. He used many more auditory words than the other interviewees.
Concluslons The data in Tahle 1 shows an increase in the degree of image ahstraction with professional level. In general the experienced chemists tended to suppress theassociative image in favor of mental models, wherens the students tended toronceptualize more by word association. Our conrlusion is that therr is an evolution in the degree of image abstraction that occurs as a person becomes more experienced with a chemical concept. Initially a student learns to connect the symbol or words with certain mental images hut goes little further than simple association. Thus the chemical tern mole caused some of
the undergraduates to respond "Oh, Avogadro's number!" with no further elaboration. They had not yet associated the term with a more ahstract imaee. At least thev had begun to e recognize the word in a chemical context. ~ h & wereiimes, however. when a kev word did not cause an initial chemical response. Several undergraduates responded to the key word bond with "James Hond" or "007". 'l'hev did eive a chemical image as well but only after a period of time.As the concept becomes more familiar, a student progresses to manipulating real-world images. For example, upon hearing solubility a more ex~eriencedstudent might describe seeing something dissolve;or upon hearing equilibrium someone a t this level might describe seeing a seesaw while moving his or her hands ;p and down. At the most abstract level of imagery development the imaees are no loneer of the observable world but are constructs based on a k r a c t models. Several graduate students described a eraoh in resvonse to rate while one facultvmember said tha't oihitals were "like sticky cotton halls".A person seems to revert to the associative or real image when a concept has not been used for a period of time. For example, one of the faculty commented after the interview that several of her reported images were not very high level because the concepts associated with them were not important in her work, and she did not use them very often. Our study suggests that students may he unable to learn chemistry, and that classroom communication may fail, hecause they cannot relate to or form the image appropriate to -~ a conceni For exam~le.a concent such as mole. which to the instructor would he'associated with a specific ehemical imaee. " . mieht either he a meanineless noise to a student or trigger an inappropriate image such as "furry little animal". I t is onlv when a student can associate written and s ~ o k e n symbuls with appropriate representational images that communication can be effective. Forisha (13) indirates that at lower levels of development inappropriate imagery might actuallv interfere with ahstract thought. ~ h o & hthe number of suhjerts studied was small, it is hard to overlook the evident relationship hetween the level of professional development as a chemist and the predominant type of image . reported. In retrospect i t does not seem surprising that many creative scientists refer to the importance of imagery in their own thought proresses. The imagery ofan abstract thinker could faril~tatecreativeinsights by allowing the person to retreat within and restructure his or her perspective. Thus there can be cognitive flexihility which would enhance the ahstract thought process. Albert Finstein ( 1 4 ) in a famous letter to the psvcholoaist Jacaues ~ a d a m a r ddescribed the importance bf visualand kinesthetic imagery in his own abstract thinking. ~
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Thr words of thr languagr, as they are written and spoken, do not srrm to play any role in my merhnnirm of thought. The psychirnl entities which seem toserve aselements in thought are certain signs and more or less clear images which can be voluntarily reproduced and combined
... . The above mentioned elements are, in my ease, of visual and
some of muscular type. Conventionalwords or other signs have to he soueht for laboriouslv in a secondarv staee. when the above mentioned associative piay is sufficient& established end can be reproduced at will.
Our studv sueeests that classroom instructional methods should con&de;that the ahility of a student to understand chemistry may be related t o the student's ability to develop specific images appropriate t o the chemical concepts. The frustrated student may be unable to shift from the associative image (such as rote chemical or mathematical formulas) to the more abstract and specific images that professional chemists use (see Fig. 3). Volume 64 Number 9
September 1987
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Acknowledgment This work was supported in part hy a grant from the Center for Research in Learning and Teaching of the h i versity of Michigan. We are grateful to Donald R. Brown and Rudolf Arnheim for their helpful suggestions during the formulation of this study.
Literature CHed 1. Reif, F. Physics Today 1986.39 (11),48. 2. Herron, J. J. Chem. Educ. 1975.52.146. 3. Wiseman. F.. Jr. J.Chem. Educ. 1979.58.484,
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4. Sheehan,P.,Ed. The Function ondNotureofMmtd1maeerv:Academie: N ~ W yor*. ..
1972.
s. W N d . J. J. h d w oeniua: ~ h . if^ ~ f h i i k ~T S~ S, ~ reprinted ~ : by iff: noily.
, 7.
8. 9.
lo. 11. 12. 13. 14.
wwd. CA, 1981. Paivio,A.Im and Ve,bolPr oc.8s.s: Holt:New York, L9,1. &der. L. RSO. E ~ W R. ~ *~980.60.5. . Weinstein. C. E.; Underwwd, V. L.;wicker, F. W.; Cubbariy, W. E., ~ d s cognitive . and ~ffecliue~ ~ o r nstratpgie8; i ~ g A C ~ ~ P N ~ ~~ C V :Y O1979. ~~. Forisha, B. J.Mental lmogory 1918,2. 209. Bueelski,R. R.Am.Psycho1. L970,25,1W2. Arnheim, R. Visual Thinking; Univ. California: Berkeley, 1969. Bdner. G.; McDaniel, E. Res. Educ. 1984.19; Ed 238 319. 1975.11.259, Forirha, B. Dov~lopmenlolPs~chol. Hadamard. J. The Pwchology oflnuantion in :ha Mathematical Field; Dover: New York, 1 9 5 4 : 142. ~
