Supplementary material

Comparing the atmosphere to a bathtub: Effectiveness of analogy for reasoning about accumulation

Submitted to Climatic Change

Sophie Guy*, Yoshihisa Kashima, Iain Walker, Saffron O’Neill

* Corresponding author

Melbourne School of Psychological Sciences, Redmond Barry Building, University of Melbourne, VIC, 3010, Australia

Phone: +613-8344-6377

Email:

  1. Comparison of demographic characteristics of the two samples (student and general public)
  2. Belief that climate change is occurring
  3. Results of mapping task

1 Comparison of demographic characteristics of the two samples (student and public)

The tablecompares the sample characteristics of Studies 1 and 2. There are differences on most variables. There was also a difference on belief in the existence of climate change between the two samples. Age, education level, and belief in climate change were controlled for in Study 2 analyses.

Demographic characteristic (%) / Study 1 / Study 2
(N=100) / (N=335)
Mean age in years (SD) / 21.21 (4.14) / 44.08 (17.05)
Female / 58 / 50
Born in Australia / 54 / 73
Education level
Did not complete school / - / 11
Completed school / 100 / 36
Tertiary educated / - / 53
Political identification
Liberal/National / 12 / 29
Labor / 15 / 23
Green / 24 / 13
Other/Don’t know / 48 / 25
Mean belief climate change is occurring (SD) / 5.74 (.91) / 5.02 (1.22)

2Belief that climate change is occurring

Six items were adopted from a study conducted by Heath and Gifford (2006) that tapped acceptance that climate change is occurring (e.g., ‘I am quite sure that climate change is occurring now’). Participants rated the items on a scale ranging from 1 ‘Strongly disagree’ through to 7 ‘Strongly agree. Item scores were summed and averaged to create a‘belief that climate change is occurring’ scale (α = .72).

We examined whether there were differences in level ofbelief that climate change is occurring acrossparticipants of different educational backgrounds. Tertiary educated participants reported significantly higher belief scores (M = 5.16, SD = 1.14) than those whose highest level was school completion (M = 4.87, SD = 1.37) and those who did not complete school (M = 4.87, SD = 1.37), however, these differences were not significant, F (2, 332) = 2.58, p = .08.

3Results of mapping task

A mapping task was included in the study to facilitate deeper processing of the analogy. It involved making explicit connections between the relational elements in the base and target analog. Participants were presented with a list of elements from the base analog (i.e., bathtub scenario) and asked to identify matching elements in the target analog (description of carbon accumulation). The first pair (water and carbon) was provided as an example. The list included the following base analog items: water, tap, inflow of water, outflow of water, level of water, drain, bathtub, bathtub overflowing. Participants could also record additional relational matches not contained in the list. The responses were coded according to the accuracy of the mapping, attracting scores of 0, 1, and 2. For example, an accurate response to the base element ‘tap’ would be ‘sources of CO2’ and would attract a score of 2. Scores for the eight mapped element responses were summed and any additional correct ‘other’ responses were added to create a total mapping score. The following table shows the descriptive statistics for the mapping score variable across the two studies.

Study 1 / Study 2
Mean (SD) / 8.86 (2.64) / 6.46 (3.44)
Median / 9.00 / 7.00
Range / 2-14.00 / 0-15.00

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