The survey was given before and after instruction in the next offering of the honor’s seminar on life in the universe and also in several sections of a nonmathematical, general education, introductory astronomy (astronomy 101) course in which life in the universe was covered as the last topic in only one or two class sessions at the end of the semester. In these sections, the Drake equation was introduced using the same, above-described, activity as it was in the honor’s course.
Seminar Course on Life in the Universe
The honor’s seminar course on life in the universe, N = 39, showed change in the responses to most items after instruction. Item 1 (Figure 3
) showed almost all students correctly identifying the estimated number of stars in the galaxy.
Almost all students in the honor’s seminar course correctly identified the approximate number of stars in the galaxy after instruction
This was also true for item 9, the only other item in the survey that had a correct response. Over 90% of respondents selected the detection of radio signals as the most likely way to communicate with life elsewhere in the galaxy. Before instruction, over 50% had selected radio signals, but about 30% had selected robot spacecraft.
Item 2 (Figure 4
) showed an overall increase in the estimates of the percentage of stars with planets. This was also true for item 3 (Figure 5
) that also showed a large decrease in the number responding that there are very few habitable planets per system. This was likely due to the geology lecture in the above list of topics covered being largely about what factors contribute to a planet being habitable or “Earth-like.”
Estimates of the number of stars with planets increased after instruction
The majority estimated very few habitable planets per system before instruction, but estimates increased after instruction
Items 4–6 showed increases in optimism about the chances of life originating, evolving to intelligence, and developing civilization on a habitable planet. Similar to the plot for item 5 (Figure 6
), all three items began with approximately half of the respondents maintaining before instruction that there was little or no chance of any of these events occurring and becoming more optimistic after instruction. However, there was little consensus in how
much more likely they estimated these events to be. This can be seen in Figure 6
. Similar numbers of respondents selected each of the choices for item 5 on the posttest. As with item 3, these changes were likely due to the fact that there were lectures explicitly devoted to each topic; the origin and evolution of life, intelligence, and civilization and technology.
Estimates of the chances of the origin and evolution of life and development of civilization on a habitable planet were more optimistic after instruction (histograms for items 4 and 6 were similar to that for item 5)
Item 7, the lifetime of technological civilization showed very little change in after instruction responses. The distribution was reminiscent of a bell-curve peaking with 35%–40% selecting 10 000 yr. There was a hint of pessimism, as 1000 yr was a more common response than 100 000 yr by a factor of about two, with about 30% and 15% choosing each, respectively.
Item 8, the chances that communication with extraterrestrial life could occur, reflects, N, the final product of all the Drake equation factors. Responses before and after instruction showed a slight shift toward pessimism. This is likely due to instruction resulting in an increased appreciation of the immense distances between the stars in our galaxy that results in planets in different systems being extremely isolated from one another. This fact was noted in many of the students’ term papers in both semesters the course was offered.
It should also be noted that further validation of the survey comes from the distribution of the after instruction responses shown for item 8 (Figure 7
). It was similar to that of the final estimates for N in student’s term papers that same semester. This was also true of the responses to item 8 before instruction and the distribution of the student’s initial estimates of N in the early semester activity in which they were introduced to the Drake equation.
A small shift after instruction toward pessimism in the chance of communication
The fact that no students selected prior to, or after instruction, that communication has already occurred could be considered encouraging. This could be because members of a population of honor’s students may be less likely to believe conspiracy theories about government cover-ups of such an event. As will be seen below, in the general education course, this was not the case.
Instruction showed very little effect on item 10 about whether extraterrestrials would be similar or different than humans and friendly or hostile. About equal numbers of respondents chose friendly and hostile before and after instruction and over 80% responded that extraterrestrials would be different than humans or unrecognizable. This was, again, before and after instruction.
Responses to item 11 comparing our technology to that of extraterrestrials that we may encounter largely favored their technology being superior to ours. The only noticeable change before and after instruction was an increase in the number of respondents that chose “much more advanced” and a decrease in those that chose “similar.” This would once again likely be due to a gain in the appreciation of how remote stars and their planetary systems are from one another in the galaxy.
Response to item 12 about who should speak for Earth vastly favored scientists before, over 60%, and after, over 70%, instruction. This could be due to students telling the instructor what they think the instructor wants to hear. Only small percentages, 10% before and less after, responded that contact could be too dangerous.
Students in several sections of introductory astronomy taught by two different instructors over three semesters completed the survey at the beginning of the semester, N = 192, before any instruction and at the end of the semester, N = 150. Instruction included coverage of life in the universe in one or two class periods at the end of the semester. The same Drake equation activity done at the beginning of honor’s seminar was part of the instruction.
As in the honor’s course, the majority of respondents chose the correct answer for items 1 and 9 after instruction. Instruction resulted in very little change for items 2–7 all involving the factors of the Drake equation. This likely reflects the fact that the Drake equation activity was a topic on only one day of instruction rather than as much as an entire class meeting or more being devoted to single factor, as in the seminar course. As shown in the plot for item 5 (Figure 8
), the responses before instruction were, in general, pessimistic. This was similar to those in the seminar. However, post instruction responses remained that way unlike those in the seminar that became more optimistic. The plot for item 2, the percentage of stars that have planets, showed not only very little change, but also no consensus response. This suggests that the typical coverage of planets and stars as in separate “units” in an introductory astronomy class resulted in very little consideration of this question.
There was very little change before and after instruction in introductory astronomy in items pertaining to the Drake equation.
Responses for items 10 and 11 also showed very little change due to instruction, item 10 heavily favoring extraterrestrials being unrecognizable with similar numbers of respondents indicating that they would be friendly and unfriendly. Item 11 responses heavily favored extraterrestrials being more technologically advanced. This was also similar to responses in the honor’s seminar.
Items 8 and 12 both showed interesting results in introductory astronomy that did not occur in the seminar course. In item 8, on the chances of contact, which is related to the final product of the Drake equation, N, nearly 15% of respondents indicated before instruction that they felt that contact had already occurred. This dropped by about a factor of two to fewer than 7% after instruction. In item 12, “Who speaks for Earth?,” prior to instruction over 40% of respondents chose that contact was too dangerous and that nobody should communicate with extraterrestrials. This was exactly as predicted by the above-mentioned instructor of introductory astronomy. This dropped to just over 10% (by a factor of four) after instruction. The large increase in the percentage that selected scientists to speak for Earth also should be noted.
During the first semester that the Life in the Universe Survey
was used in introductory astronomy, the pretest was given toward the end of the semester, right before the actual instruction on life in the universe, instead of at the beginning as it was in subsequent semesters. This means that the students had experienced nearly an entire semester of introductory astronomy before
taking the survey. The only major differences because of this were seen in responses to item 12. It can be seen in Fig. 10
that where the number of respondents choosing scientists as those who should speak for Earth was over 50% on the pretest, N = 85, and rose only to about 58% on the posttest, N = 92. Also, the percentage that felt contact would be too dangerous was just over 10% on the pretest and remained about the same on the posttest. When compared to the histogram for item 12 in Figure 9
, this indicates that the significant changes in these responses seen in sections in the subsequent semesters, where the pretest was given before any
instruction, may have occurred as a result of the earlier instruction in the introductory course prior
to explicit instruction on life in the universe.
Instruction in introductory astronomy resulted in less students responding that contact already has happened in item 8 and that contact would be too dangerous in item 12. Also in item 12, instruction resulted in a large increase in students choosing scientists as the ones who should speak for Earth
Comparison of this histogram with the item 12 histogram in Figure 9
shows that when the survey was given right before and right after coverage of life in the universe in introductory astronomy, the changes in the number of students selecting scientists to speak for Earth and that contact is too dangerous appears to have occurred prior to explicit instruction on life in the universe