Biochemistry is considered by medical students as a difficult subject to study, while it’s also an equally challenging task for the teachers to teach [1]. Unlike the subjects where it may be possible for students to correlate with specimens, dissections, or real life examples, conceptualization in biochemistry is often, a challenge [1]. Traditional didactic teaching and textbooks may not suit all students since learning preferences are different among individuals [2]. The new generation of medical students is more proficient with the use of technology. Hence, educators need to come up with strategies to assist self-learning [3]. In this context, podcasts can be a useful educational technology that can cater to learners with auditory, visual or mixed learning preferences [4]. The term ‘podcast,’ now refers to audio/video files that can be downloaded or streamed on portable media players [5]. Podcasting was initially developed for entertainment but has been tried in the fields of medical, dental, nursing and veterinary education [6–9]. Understandably, students have the advantage to access podcasts by devices of their choice (smartphones, tablets, and computers). Since podcasts can be used anywhere, anytime, they enable students to learn at their pace [5, 10].

There is a notable enthusiasm among educators for the adoption of podcasts into medical education [11–13]. On the other hand, a few educators also raise caution in using podcasts, citing lack of credible evidence [14]. Additionally, the success of this technology also depends on other factors such as the purpose of podcasts, type of podcasts, mode of delivery, target audience, etc. Hence, there are still gaps in our understanding of the utility of podcasts in medical education. Despite the available evidence to support the use of podcasts, currently, there is no defined role for it in medical education [14]. The consensus is that podcasting should be used to complement rather than replace traditional teaching for a richer learning experience [6, 12, 15].

In the past, several studies have used podcasts in medical education for different purposes. Podcasts have been tried as a teaching method in comparison to traditional didactic teaching [8, 16–21] or text-based learning [22, 23]. Most other investigators have used podcasts as tools to supplement routine teaching practices [6, 7, 10, 24–34]. Alternatively, a few investigators have tried podcasts as a preparatory tool for “flipped-classroom” which allows teaching hours to be utilized for problem-solving interactions [35, 36].

An additional factor that can influence the success of podcasts, albeit less studied, is the length of podcasts. Based on a classification by Carvalho et al., podcasts can be of different types based on their length: short (1–5 min), moderate (6–15 min) and long (>15 min) duration [37]. A common practice among several universities has been to record and provide entire lecture sessions, analogous to long-duration podcasts [38–40]. However, it is known that long duration podcasts are less preferred by listeners [41]. The general recommendation is to maintain the length of podcasts <15 min, considering the attention span of listeners [37, 38, 42]. In the past, several researchers have mainly used moderate-duration podcasts for their investigation [6, 8, 27, 29, 30, 34]. Short-duration podcasts are less studied, and there are only a few studies in this regard [28, 43, 44]. Aguiar et al. used short-duration podcasts for delivering learning outcomes and guidelines for reading the topic without providing any conceptual information, as such [43]. In a study by Narula et al., clinical clerks were provided with 5-min podcasts each designed to cover a selected core internal medicine concept [28]. Another study used short-duration podcasts for information delivery and student feedback on evolution and heredity topics [44]. However, students’ perceptions towards short-duration podcasts are less understood.

Short-duration podcasts are unique since they are capsules of high-yield information for students to review quickly. However, an inherent disadvantage of short-duration podcasts is the limited information that can be conveyed due to the time barrier. This factor can be critical from the students’ perspective; because gathering information within short-duration may require some prior knowledge on the topic. Hence, it is important to analyze the usefulness of podcasts among medical students. This pilot study was undertaken to analyze the perceptions and preferences of medical students towards short-duration podcasts in biochemistry. An exploratory analysis of students’ usage of podcasts and its impact on performance in summative assessments was also undertaken.

The study was conducted in the Department of Biochemistry at Christian Medical College, Vellore, India from December 2015 to March 2016. The study protocol was approved by the Institutional Review Board (IRB). First-year medical students (N = 100) from the Batch of 2015 from the institution were invited to participate in the study. Since the investigator (AR) and participants were acquainted with each other, the study had a post-positivistic approach. The investigator’s speculation was that short-duration podcasts would be useful as supplementary learning tools.

Ninety-four students consented to participate in the study. Feedback indicated that 41 students (43.6%) used 3MTLs for both topics, 34 students (36.2%) used for one of the topics while 19 students (20.2%) did not use 3MTLs. The usage statistics from the e-learning portal indicated that at the end of the study period, the total numbers of views and visitors for 3MTLs were 477 and 308, respectively (Table 1).

For analysis of responses from the Part B questionnaire (for data from items B1 to B10, see Additional file 4: Table S3), students who indicated they did not use 3MTLs for either of the topics (n = 19) were excluded. The majority of responses indicated that students used 3MTLs for revision while, a smaller percentage also used it for orientation, and studying (Fig. 1i). Smartphones and laptops were the major gadgets used by students to access 3MTLs (Fig. 1ii). When questioned about their perception of the length of the podcast, 37 students (49.3%; Fig. 1iii) indicated that the time duration of podcasts was optimal, while an equal proportion felt that duration can be increased, preferably to 5 min. Mean scores on the rating of the quality of 3MTLs were lowest for ease of downloading (streaming) on e-learning and highest for the use of simple, clear language (Fig. 2). Mean scores for the usefulness of 3MTLs were lowest for motivation obtained to the read the topic and highest for helping to prepare for the test (Fig. 2). Also, an overwhelming majority (96%; n = 72) of students indicated that they would recommend 3MTLs for other topics in future.

Overall, average scores in Test_3MTL were not different when compared with Test_P or Test_S or among student groups based on 3MTLs usage (Fig. 3). However, the difference of scores in pairwise comparisons (Test_3MTL vs. Test_P; Test_3MTL vs. Test_S) was statistically significant (Table 3). In the pairwise comparisons with students groups stratified based on 3MTL usage, the difference was significant amongst 3MTL: Heavy-users in Test_3MTL vs. Test_P. In the comparison of Test_3MTL vs. Test_S, all three subgroups showed significant pairwise differences. Also, the magnitude of the score difference amongst 3MTL: Heavy-users in pairwise comparisons were higher than both Intermediate and Non-users (Table 5). Further, 3MTL: Heavy-users were sub-classified into tertiles based on their average scores in historical assessments and pairwise comparisons were repeated (Additional file 5: Table S4). Notably, only the Above-average performers among the 3MTL: Heavy-users had consistently higher pairwise scores in the Test_3MTL vs. Test_P and Test_3MTL vs. Test_S comparisons (Table 5). Other demographic characteristics were similar in the subgroups of 3MTL: Heavy-users (data not shown).

Groups	N	Paired differences				Significance (2-tailed)
		Mean	SEM	99% Confidence interval
				Lower	Upper
T3MTL - TP
Overall	94	1.67	0.43	0.53	2.8	<0.001
3MTL: Heavy-users	41	2.32	0.74	0.32	4.31	0.003
3MTL: Intermediate-users	34	1.07	0.67	−0.75	2.9	0.117
3MTL: Non-users	19	1.33	0.76	−0.86	3.52	0.098
T3MTL - TS
Overall	92	3.3	0.43	2.19	4.47	<0.001
3MTL: Heavy-users	41	4.20	0.66	2.43	5.97	<0.001
3MTL: Intermediate-users	32	2.63	0.73	0.62	4.64	0.001
3MTL: Non-users	19	2.63	0.91	0.003	5.26	0.01
Analysis of subgroups of 3MTL: Heavy-users
T3MTL - TP
Below-average performers	13	2.94	1.74	−0.84	6.73	0.116
Average performers	14	2.57	1.38	−0.41	5.55	0.085
Above-average performers	14	1.48	0.58	0.24	2.73	0.023
T3MTL - TS
Below-average performers	13	6.40	1.07	4.06	8.75	<0.001
Average performers	14	4.66	1.33	1.78	7.54	0.004
Above-average performers	14	1.70	0.51	0.59	2.80	0.005

Paired differences of scores in the test (Test_3MTL) which had implemented 3MTLs were compared with assessments that immediately preceded (Test_P) and succeeded (Test_S). Based on self-reported 3MTL usage, students were divided into 3 groups for comparison [3MTL: Heavy-users (used 3MTLs for two topics); 3MTL: Intermediate-users (used 3MTLs for some of the topics); 3MTL: Non-users (did not use 3MTLs]. For intragroup comparison, students were classified into tertiles based on their average scores in the historic assessments conducted prior to Test_P (Below-average performers, Average performers, and Above-average performers). All tests were scored out of a maximum of 30. SEM: Standard Error of Mean. Paired t-test was used for all comparisons. Significant p values are highlighted in bold

This pilot study was designed to analyze the perceptions of medical students to short-duration podcasts in biochemistry. Specifically, the study was designed to analyze how and why students accessed podcasts and their experiences in the process. Additionally, an exploratory analysis of the use of podcasts and students’ performance in the assessments was also done. Overall, podcasts were well received in this study and students perceived 3MTLs mainly as a supplementary learning tool. Students felt that 3MTLs were a valuable addition to routine teaching practice and suggested extending it to other topics. The results of the qualitative and quantitative analysis indicated that students mainly used 3MTLs for revision purpose after having read the topic. Particularly, students reported using 3MTLs for a quick review before assessments. This aspect was corroborated with a spike in the number of visitors and views of 3MTLs a day before assessment in the e-learning portal (data not shown). A smaller proportion of students used 3MTLs as a preparatory tool for gaining a topic overview. Additionally, students also felt that 3MTLs were helpful in improving their understanding of the topic, clarify concepts and focus on important points. These findings are consistent with other previous studies involving podcasts [5, 24, 30–32, 53].

Interestingly, half of the students perceived that the length of podcasts was optimum while an equal proportion suggested that the duration of podcasts can be increased to about 5 min. The survey by Matava et al. showed that podcast listeners preferred different podcast durations depending on the content [41]. For case presentations, procedural skills, journal article summaries, and discussions, the preferred podcast duration were 5–15 min, while for recorded lectures, a 15–30 min podcast was preferred; podcasts >45 min were least preferred. Matava et al. explain this observation as “respondents perceive that a certain amount of time is necessary to convey key learning objectives” [41].

Respondents in our study also indicated a preference to the audio and visual component in podcasts similar to few earlier observations [5, 34, 41]. Students noted that the teacher’s voice-over in the background was reassuring and useful in learning while the visual component in the podcasts made them lively. A few students felt that 3MTLs were more useful and interesting compared with reading texts. However, these observations were not shared by the majority, and a few students specified their preference to reading as the reason for not using 3MTLs. These observations further reiterate about different learning preferences among students. Certainly, the inclusion of audio-visual component in podcasts would be advantageous for students with aural, visual or multimodal learning preferences [2].

It was noted that the majority of students reported using smartphones to access 3MTLs followed by laptops. This observation was an interesting contrast since, several studies conducted before 2014 have reported that podcasts were accessed by listeners mainly through computers followed by portable media players [5, 6, 10, 31–33, 37, 41, 54–57]. However, general podcast listenership trends in the USA and UK has shown a shift towards smartphones after 2014 [58, 59]. Keeping in line with this trend, the more recent studies in medical education also indicate that podcasts are mainly accessed through smartphones over computers [60, 61] and our results corroborate with this observation.

Attention to technological issues of podcasts and their perceptions to users are important. Earlier observations show that technological issues are often cited by students as barriers to accessing podcasts [32]. Findings from this present study also indicate technical issues: ease of downloading (streaming) 3MTLs had lower ratings (Fig. 2 ii) and several students who did not access podcasts cited download issues and bigger file size as reasons. Additionally, the ease of downloading was rated lower among students who accessed 3MTLs on phones compared to computers (data not shown). A probable reason for this could be that podcasts were made available through the institution’s e-learning portal, a website best suited for use with computers. An alternative option to overcoming issues with the medium of delivery would be to make podcasts available through more than one portal that allows video streaming (e.g., YouTube, Facebook). Other device-related technical factors could be issues related to internet connectivity, server, browser compatibility, device’s storage capacity, software or hardware. Concerning the format of podcasts, the major feedback provided by students in this study was towards the improvement of audio and video quality. A major reason could be that only basic equipment was used for recording the podcasts. The investigator’s lack of experience in podcasting could be another contributing factor. Also, 3MTLs were made available in 320 × 240 image resolution ideally suited for viewing in handheld gadgets. It is possible that students who accessed podcasts on devices with larger screens may have rated the video quality lower. However, production of high-quality video podcasts would also require more preparation time, costlier recording equipment, and larger file sizes, amongst other factors. The costs and benefits would need to be weighed while considering the production of video podcasts. However, it is important for podcasters to be aware of these issues while deciding on the format and medium of delivery of podcasts.

An exploratory comparison of scores in summative assessments also suggested that use of 3MTLs was associated with better performance. A few studies in the past have used a pre-test-post-test quiz to assess the effectiveness of podcast implementation in comparison to lecture-teaching and showed weak evidence for improvement in podcast group [25–27]. Comparison between teaching with lectures and video podcasts by a crossover trial observed that student evaluations were not different between the two formats [8]. In this study, the overall mean scores were not different between students based on 3MTLs usage, suggesting that factual recall is similar amongst students, irrespective of podcast usage. However, the pairwise comparisons revealed better scores amongst 3MTL: Heavy users. It is further possible that a subset of students in 3MTL: Heavy-users may be the primary beneficiaries of 3MTLs since sub-stratification of 3MTL: Heavy users showed that benefit was consistently observed only amongst ‘Above-average performers.’

Some potential confounders of this study are factors about the student’s background related to school education, study habits, learning preferences, and availability of gadgets to access 3MTLs (Additional file 6). The questionnaire was designed to collect information on some of the above factors, but, no patterns were detected in the use of 3MTLs (data not shown). Participants were recruited by convenience sampling, and hence there is a possible sampling bias in the study. There is a possibility of response bias considering that investigator (AR) and participants are well acquainted and AR was also involved in the delivery of lectures, creation on 3MTLs and feedback collection. Another limitation of this study would be the lack of baseline pre-test scores on the topics under study. Finally, data on the total number of views and visitors from the website statistics may be an underestimate, since it does not account for files downloaded and transferred to students by other means. In comparison to previous studies, there are also a few aspects of the methodology of this current study that are worth mention. A major difference would be that fixed, short-duration podcasts aimed at providing highlights of the topic were used in this study, while others have used moderate- or long-duration podcasts [8, 25, 30, 34]. Also, in this study 3MTLs were only provided as a supplementary tool, and hence, assessments were held as per routine teaching schedule, and no additional assessments (specifically related to 3MTLs) were conducted.

To conclude, short-duration podcasts are useful supplementary tools in medical education. Analysis of the feedback from students suggests that they consider podcasts as a very useful tool for review and preparation for assessments. The authors’ beliefs about the future of this media concur with others who view podcasts as a supplementary learning tool but not meant to replace traditional teaching.