Keywords

1 Introduction

Due to continuous shifts in the age structure, elderly people, their needs, and demands, move into the focus of today’s society [1]. Regarding the European Union, Germany is one of the countries where demographic change proceeds rapidly, since nearly one in five people is 65 years or older – provided that this number will rise to one-third by 2060 – while the working-age population steadily declines [2, 3]. As aging restricts health and mobility, new care measures are needed to bridge the gap between growing care needs and shortages of skilled workers [4]. To this, ambient assisted living (AAL) technologies and systems, such as the ultrasonic whistle, provide innovative solutions to increase independence in old age and relieve health care.

In general, AAL is referred to as “the use of information and communication technologies (ICT), stand-alone assistive devices, and smart home technologies in a person’s daily living and working environment to enable individuals to stay active longer, remain socially connected, and live independently into old age” [5]. The ultrasonic whistle is a new assistive device that is to be used as an integrated part of supportive home environments and can be installed at little cost and effort, e.g., in switches fixed to the wall. The user interface is particularly designed for people with motoric disabilities, who can easily access and operate the ultrasonic whistle on a large and robust surface at the push of a button, for example. As a holistic assistance system, the ultrasonic whistle is adaptable to personal needs, such as the automation of domestic tasks, safety prevention, and fall detection.

Though, assistive devices facilitate aging in place, they are not accepted per se due to perceived restrictions, such as privacy concerns within living space [6]. In fact, the perception and evaluation of AAL technologies and systems differ among users [7]. Hence, the willingness to adopt innovative technology strongly depends on user-diverse factors, such as trust when dealing with technology [8], data security and control needs [9], but also personal experience with care and disabilities [10]. Particularly with regard to older adults, a central but heterogeneous user group of AAL, there are different needs and demands on what an assistance system should (not) be able to do [11]. Hence, this study’s aim was to examine the assessment of ultrasonic whistles in home care with special regard to older users’ benefit and barrier perception, since so far there is only little known about requirements of the elderly in this context.

2 The Acceptance of AAL in an Aging Society

In recent years, the majority of frail and older people in Germany has been cared for by family members at home, since nursing staff decreases [12], but also, because many (care-dependent) people prefer to grow old in their familiar environment [13]. This development opened up other ways of long-term care, besides traditional nursing homes and care wards, leading to “aging in place” as a growing research branch [e.g., 14,15,16,17,18,19]. In order to support aging in place and relieve those affected, ambient assisted living (AAL) technologies and systems have been investigated in a variety of applications and contexts to meet individual user demands and care needs [e.g., 20,21,22,23]. In practice, AAL includes stand-alone devices, which are often visible for others (e.g., stair lift), as well as holistic systems that are unobtrusively integrated into the living environment (e.g., floor sensors for fall detection) to prevent stigmatization, support residents and their relatives in daily life, and enhance caregiving tasks [24,25,26,27].

In the present study, the focus was set on the ultrasonic whistle, a new AAL application for home care. The final ultrasonic whistle will be small and made of soft silicone, so it can be installed in user friendly switches and easily retrofitted in different places (e.g., living spaces and objects). Technically, ultrasound is generated mechanically (when the switch is actuated) and transmitted via air towards microphones and receivers for decoding [28, 29]. Receiving devices are installed in ceiling lights or other home devices nearby, which are permanently connected to electricity, to ensure a reliable signal transmission. The ultrasonic signal is frequency coded using different pipe lengths to activate one specific function. In particular, the ultrasonic whistle serves for home automation (e.g., automatic door and window opening or lightning control) and emergency services (e.g., emergency calls to outside assistance).

Against the background of an aging society, the key is to adjust AAL technologies and systems to the needs of older users, as they are at a higher risk for diseases and care [30]. One of the main challenges is, that the adoption of assistive devices in the personal living environment can be limited by perceived barriers (e.g., low usability, technical support, and experience) [31]. This is particularly important with regard to older adults, who are less expertized [9] and may be restricted in the use of technology by memory loss or motoric disabilities, for example [32]. However, disease incidences [33], the way people feel satisfied with their personal aging process [34], as well as the perceived need for technical assistance (e.g., due to disabilities) [10] differ between individuals. Hence, it is essential to address “the elderly” as a heterogeneous user group [17].

To predict the intention to use and usage behavior, age was integrated as a moderating factor into technology acceptance models, here to be mentioned in particular UTAUT (unified theory of acceptance and use of technology) [35] and its extension to UTAUT2 [36]. However, both models lack the possibility of context transfer [37] – as they were not specifically tested in the sensitive context of AAL – and the consideration of age as a multidimensional factor (e.g., including self-perceptions of and attitudes towards aging [34, 38]).

For a deeper understanding, user studies focused on older adults’ personal requirements concerning the use of AAL, with special regard to trade-offs between perceived benefits and barriers [e.g., 39,40,41]. For this purpose, diverse research approaches were conducted, using qualitative and quantitative methods (e.g., interviews [42], focus groups [32], and scenario-based questionnaires [43]) as well as participatory [44] and mixed-method designs [45]. Results showed that older users are aware and appreciate the advantages of AAL as great support for aging in place – but also, that it affects their perception and meaning of home, as the necessity of using assistive devices creates an awareness of own health insufficiencies and users may behave differently because of monitoring systems in their living environment [32, 42].

Major perceived benefits referred to an increased feeling of independence, a stronger sense of security, and the opportunity to reduce burdens on family caregivers [13, 41,42,43]. In particular, visual and hearing aids, the automation of home infrastructure, and reminder systems for appointment notices were appreciated to cope with everyday tasks [32]. In contrast, privacy concerns, the feeling of losing control over technology and being restricted in one’s own behavioral freedom, less human contact as well as usability risks were detected as strong perceived barriers [31, 32, 41,42,43]. As personal characteristics (e.g., confidence), attitudinal factors (e.g., the perceived usefulness of a technology), and the social environment (e.g., family support) influence the decision to adopt or reject technology assistance at home [31], there is a need to take greater account of user factors, particularly in connection with the technology acceptance of elderly people [46].

Concerning the ultrasonic whistle, previous studies showed that its acceptance depended on different functions and usage locations, provided that emergency applications in the bathroom were appreciated the most – with regard to the users’ perspective, biological age and attitudes towards aging seemed to affect the adoption of ultrasonic whistle in home care [47]. As the technology is still under development, there is great potential to iteratively integrate user requirements into the production process to achieve high acceptance levels.

3 Method

The following section presents the study’s empirical approach, the design of the online questionnaire, a description of the study’s sample as well as detailed insights regarding the relationships between the user factors age, aging, and health status.

3.1 Empirical Design

The current study aimed for (a) an investigation of older people’s attitude towards aging and (b) the examination of older people’s benefit and barrier perception with regard to AAL technology based on usage of ultrasonic whistles. For both research aims an empirical approach was needed considering individual user factors as potential influencing parameters, e.g., gender, health status, or attitude towards aging (only for benefit and barrier perception).

An overview of the underlying empirical research design is presented in Fig. 1. The items of the online questionnaire based on a literature review (e.g., attitudes towards aging) as well as on a preceding qualitative study [38], in which in particular diverse benefits and barriers were identified with regard to using an AAL system based on ultrasonic whistles within the own home environment.

Fig. 1.
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Empirical research design.

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The first part of the questionnaire referred to independent variables including demographics of the participants such as age, gender, educational level, occupation, income (optional), and living circumstances. Additionally, this part also considered the participants’ health status by asking if the participants (answer options: yes/no) suffer from a chronic illness, depend on care, depend on using medical assisting technology, or have a physical impairment. If a participant answered one of these aspects with “yes”, he or she was categorized as “ill” and otherwise as “healthy”. A last aspect belonging to the independent variables, referred to the participants’ attitude towards aging using 10 items focusing on the areas health, active aging, dealing with change, autonomy, and social integration. The items based on a preceding study [38], included potential positive as well as negative aspects of aging, and were assessed on a six-point Likert scale (min = 1: “I strongly disagree”; max = 6: “I strongly agree”).

Following this first part of the questionnaire, a scenario was used in order to emphasize the participants with a situation of care needs due to health restrictions. The scenario contained a short explanation of an AAL system based on ultrasonic whistles and described possible functions and applications, i.e. using ultrasonic whistles as emergency button or for fall detection by integrating them into the floor. Within the scenario, the participants were asked to imagine the situation that he/she or a close family member is in need of care and an AAL system based on ultrasonic whistles was integrated unobtrusively in the home environment in order to enable an active and autonomous longer staying at home. The technical description as well as the scenario were evaluated in a pretest with participants of different ages ensuring comprehensibility and clarity.

Following the scenario, the participants were asked to evaluate perceived benefits and perceived barriers of the AAL system, as well as their acceptance in terms of their intention to use the described AAL system in their daily routine. As first dependent construct, perceived benefits were evaluated using 10 items (α = .918) focusing on safety, relief, independency, mobility, invisibility, but also on technology-specific aspects in terms of independency of electricity and batteries. As a second construct, perceived barriers were assessed using 11 items (α = .891) reaching from data security and privacy-related aspects to concerns about finances, surveillance, or control. Finally, the acceptance of the described AAL system was evaluated using 4 items (α = .886) referring to the participants’ behavioral intention to use the system. All items of the dependent variables were evaluated using six-point Likert scales (min = 1: “I strongly disagree”; max = 6: “I strongly agree”).

Overall, evaluations above the mean of the scale (>3.5) indicated acceptance, whereas evaluations below the mean of the scale (<3.5) indicated rejection of a statement or construct.

3.2 Sample Description

In total, 188 (= N) participants completed the questionnaire, aged between 50 and 93 years, with an average of 61.8 years (SD = 9.8). The sample consisted of 105 (55.9%) females and 83 (44.1%) males. The educational level was above average with 44.1% holding a university degree [48].

On a voluntary basis, 151 (80.3%) participants provided information on their monthly net household income, which was mostly between 2,000 and 3,000 euros. With regard to their home environment, the majority (65.4%) lived in flat-sharing communities, provided that the intention to stay at home in old age was commonly high (M = 5.2; SD = 1.0), next to the wish to be cared for at home (M = 4.0; SD = 1.5), whereas moving to relatives (M = 2.4; SD = 1.3) or nursing homes (M = 2.3; SD = 1.2) received comparatively little approval. Overall, attitudes towards aging (M = 4.1; SD = 0.7) and attitudes towards technology (M = 4.5; SD = 1.0) were high. Except for blood pressure monitors (61.2%), personal experience with medical devices, such as motion detectors (17%), wheelchairs (4.3%), emergency systems (4.3%), and bathtub lifts (1.1%), was low. Yet, 85 (45.2%) of the participants indicated to be health-restricted in terms of acute physical impairments, chronic diseases, and/or being dependent on care assistance. Data was collected in Germany and on average the participants needed 20 min to complete the questionnaire.

3.3 Age, Aging, and Health Status

Concerning AAL, older people are a major but heterogeneous user group, since aging, its onset and extent, is an individual process with varying demands and needs [17, 30]. For a better understanding of age-related acceptance factors, we formed two age groups considering older people in working-age (50–65 years), who came into question as family caregivers, and the elderly (≥66 years) as potentially care-dependent patients. Descriptive age group profiles of demographic and attitudinal data are presented in Table 1. With regard to aging perceptions, both age groups were positively inclined. However, slight differences were observable, indicating that people in working-age (M = 4.1; SD = 0.6) tended to be a little more optimistic concerning issues such as health, dealing with change, active aging, social integration, and autonomy than the elderly (M = 4.0; SD = 0.8).

Table 1. Descriptive age group profiles of demographic and attitudinal data.
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Correlation analyses (see Table 2) did not confirm a relation between age and attitudes towards aging (rs = −.057; p = .441; n.s.). However, health status correlated with attitudes towards aging (rs = .348; p < .01), indicating that people in good health shared more positive aging concepts compared to those who were affected by health restrictions.

Table 2. Correlation analyses of user factors (**p < .01).
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For a closer regard to attitudes towards aging depending on the participants’ health status, two health groups were formed: The first group consisted of “healthy” participants (n = 103) who were not affected by any health restrictions and thus, also not dependent on nursing services, whereas the second group of “ill” participants (n = 85) indicated to suffer from acute or chronic diseases and, partially, being care-dependent. Descriptive health group profiles of demographic and attitudinal data are presented in Table 3.

Table 3. Descriptive health group profiles of demographic and attitudinal data.
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Overall, the group of healthy participants had more positive attitudes towards aging (M = 4.3; SD = 0.6) compared to the ill ones (M = 3.9; SD = 0.7). In detail (see Fig. 2), for the healthy group, aging in particular included staying in contact (M = 5.5; SD = 0.7) with others, next to making plans (M = 5.0; SD = 0.8), being more relaxed (M = 4.8; SD = 1.0), and keep on learning (M = 4.6; SD = 0.9), whereas pessimistic aging concepts, especially less enjoyment (M = 2.6; SD = 1.2), did not seem to bother them that much. In contrast, the group of ill participants tended to evaluate negative aging attitudes more strongly, in particular the fear of being less fit and lively (M = 4.4; SD = 1.2) and decreasing health (M = 4.3; SD = 1.0), as well as being dependent (M = 3.8; SD = 1.3) on others, although, their perception of positive aging concepts was still high.

Fig. 2.
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Evaluation of attitudes towards aging between two health groups (means).

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4 Results

The following section presents the study’s results starting with the evaluations of benefits and barriers with regard to the whole sample. Afterwards, the results of a cluster analysis are detailed in order to understand user-specific evaluation patterns concerning benefit and barrier perceptions of a specific AAL technology.

4.1 Overall Evaluation of Using Ultrasonic Whistles in Home Care

In general, the acceptance of ultrasonic whistles in home care was rather high (M = 4.0; SD = 1.2) with minor evaluation differences concerning different usage locations and installation sites. According to this, the participants agreed to use the ultrasonic whistle in the bathroom (M = 4.7; SD = 1.2) rather than in the bedroom (M = 4.5; SD = 1.3) and living room (M = 4.4; SD = 1.4). Besides, the installation on doors (M = 4.2; SD = 1.5), wall switches (M = 3.9; SD = 1.5), and windows (M = 3.8; SD = 1.5) was more acceptable compared with cupboards (M = 3.6; SD = 1.5), floor mats (M = 3.5; SD = 1.6), and chairs (M = 3.5; SD = 1.5).

Concerning perceived benefits of using ultrasonic whistles in home care, all items were marked with approval (see Fig. 3). Above all, an increased feeling of safety (M = 4.9; SD = 1.1) and independence of electricity and batteries (M = 4.8; SD = 1.3) were highly valued within the whole sample, followed by higher independence from others (M = 4.3; SD = 1.3) and more autonomy in everyday life (M = 4.3; SD = 1.3), multifunctionality (M = 4.2; SD = 1.3), unobtrusive technology (M = 4.2; SD = 1.3) as a protection from stigmatization, and maintaining mobility (M = 4.1; SD = 1.3). In comparison, environment protection (M = 4.0; SD = 1.4), physical relief (M = 3.9; SD = 1.4), and time savings (M = 3.5; SD = 1.3) were less decisive.

Fig. 3.
figure 3

Evaluation of perceived benefits regarding ultrasonic whistles in home care (means).

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With regard to perceived barriers (see Fig. 4), in particular the fear of data abuse (M = 3.6; SD = 1.4) and self-funded finance (M = 3.6; SD = 1.4) were assessed as restrictions on the willingness to use ultrasonic whistles in home care. In contrast, data transfer to third parties (M = 3.5; SD = 1.4), the feeling of surveillance (M = 3.3; SD = 1.3), restriction of privacy (M = 3.2; SD = 1.3), and an error rate (M = 3.1; SD = 1.1) due to interfering noises (for example in the background) were not perceived as use-inhibiting. The same applied to less human contact (M = 2.9; SD = 1.3), deficient usefulness (M = 2.8; SD = 1.2) in comparison with other technologies, loss of control (M = 2.5; SD = 1.2), deficient aesthetics (M = 2.4; SD = 1.0), and less self-determination (M = 2.4; SD = 1.2).

Fig. 4.
figure 4

Evaluation of perceived barriers regarding ultrasonic whistles in home care (means).

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4.2 User-Specific Evaluation of Perceived Benefits and Barriers

To get a broader understanding of the perception of perceived benefits and barriers, a deeper analysis and investigation of the participants’ evaluation was necessary. For this purpose, a two-step cluster analysis was chosen (hierarchical and K-means cluster analysis) [49] identifying user segments based on their evaluations of (a) perceived benefits and (b) perceived barriers.

Starting with the evaluation of perceived benefits, the hierarchical cluster analysis identified a three cluster segmentation as best segmentation solution in the data set. The first cluster contained n = 76 (40.4%) participants, the second cluster comprised n = 88 (46.8%) participants, and n = 24 (12.8%) participants were part of cluster 3. Subsequently, a K-means Cluster analysis was applied and segmented the respondents into three distinct groups based on the evaluation of perceived benefits. In a next step, ANOVAs confirmed the validity of the cluster segmentation, as the three clusters significantly differed (a) with regard to demographic characteristics (see Table 4) and (b) regarding all perceived benefit items.

Table 4. Demographic characteristics and intention to use the ultrasonic whistle of the segmented clusters (perceived benefits).
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With regard to the demographic characteristics, inference statistical analyses revealed that the three groups differed significantly regarding their attitude towards aging and gender (see Table 4). In contrast, the clusters were not influenced by the participants’ age or health status. Cluster 1 contained a clearly higher proportion of women than men and hold the comparatively least positive attitude towards aging. Cluster 2 was the largest group of participants holding a nearly equal distribution of women and men and also a clearly lower expressed positive attitude towards aging than Cluster 3. Cluster 3 represented the smallest group of participants and was characterized by a slightly higher proportion of men than women as well as the most positive attitude towards aging compared to the other two groups.

As a further criterion, the intention to use the ultrasonic whistle was investigated with regard to the three clusters. The results revealed significant differences (F(2,187) = 33.449; p < .01) indicating the highest usage intention for Cluster 1, a neutral intention to use for Cluster 2, and a slight negative intention to use for Cluster 3. Based on these differences and in accordance with the evaluation of benefits (see Fig. 5), Cluster 1 was simplified called “Adopters”, Cluster 2 the “Undecided”, and Cluster 3 “Rejecters”.

Fig. 5.
figure 5

Evaluation of perceived benefits differing between three clusters (means).

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Figure 5 shows the evaluation of benefits differentiating between the three identified clusters. Cluster 1, the “Adopters”, clearly evaluated all benefits positively indicating a high acknowledgement of all potential benefits of using the ultrasonic whistle. Thereby, independence of electricity and batteries (M = 5.5; SD = 0.7) as well as increased feeling of safety (M = 5.5; SD = 0.6) represented the most confirmed benefits, while environment protection (M = 4.8; SD = 1.1) and time savings (M = 4.6; SD = 1.0) received lower, but still high agreements from this group.

In contrast, almost all potential benefits were clearly rejected by Cluster 3, the “Rejecters”. This indicates that this group did not perceive the evaluated aspects to be “real” benefits. Thereby, time savings (M = 1.9; SD = 1.4) and environment protection (M = 1.9; SD = 1.3) represented the strongest rejected benefits, while increased feeling of safety (M = 3.5; SD = 1.8) received the highest evaluations of this group.

For the “Undecided”, Cluster 2, the evaluations showed more heterogeneous patterns: the participants acknowledged an increased feeling of safety (M = 4.7; SD = 0.8) as well as independence from electricity and batteries (M = 4.6; SD = 1.0) as benefits, showed slight agreements towards most of the other aspects, e.g., more autonomy in everyday life, and slightly rejected physical relief (M = 3.4; SD = 0.9) and time savings (M = 3.1; SD = 0.8) to be benefits of the ultrasonic whistle’s usage.

Considering the evaluation of perceived barriers, the hierarchical cluster analysis also identified a three cluster segmentation as optimal segmentation solution in the data set. The first cluster comprised n = 55 (26.1%) participants, the second cluster contained n = 84 (44.7%) participants, and n = 49 (26.7%) participants were part of cluster 3. Similar to the procedure for the perception of benefits items, a K-means Cluster analysis was applied and segmented the respondents into three distinct groups based on the evaluation of perceived barriers. In a next step, ANOVAs again confirmed the validity of the cluster segmentation, as the three clusters significantly differed (a) with regard to demographic characteristics (see Table 5) and (b) regarding all perceived barrier items.

Table 5. Demographic characteristics and intention to use the ultrasonic whistle of the segmented clusters (perceived barriers).
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Taking demographic characteristics into account, the three identified barrier clusters differed also significantly regarding gender and attitudes towards aging and were not influenced by the participants’ age or health status.

Cluster 1 contained a higher proportion of men than women and hold a less positive attitude towards aging compared to Cluster 2. Cluster 2 represented the largest group of participants with a higher proportion of women than men and the comparatively most positive attitude towards aging. Cluster 3 was characterized by the comparatively highest proportion of women and the least positive attitude towards aging.

As a further criterion, the intention to use the ultrasonic whistle was investigated with regard to the three barrier clusters. The results revealed significant differences (F(2,187) = 8.412; p < .01) indicating the highest usage intention for cluster 1, a slight positive intention to use for cluster 2, and a neutral intention to use for Cluster 3. Based on these differences and in accordance with the evaluation of barriers (see Fig. 6), Cluster 1 was simplified called “Adopters”, Cluster 2 the “Undecided”, and Cluster 3 “Rejecters”.

Fig. 6.
figure 6

Evaluation of perceived barriers differing between three clusters (means).

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Figure 6 shows the evaluation of barriers differentiating between the three identified clusters. Starting with Cluster 1, a clear rejection of all potential barrier aspects was striking. Thus, this group did not perceive any of the aspects as “real” barriers of using the ultrasonic whistle in home care. Thereby, loss of control (M = 1.5; SD = 0.6) and less self-determination (M = 1.5; SD = 0.6) represented the most rejected aspects, while fear of data abuse (M = 2.8; SD = 1.2) was comparatively least rejected by this group.

In contrast, Cluster 3 showed partly high agreements of some barriers (i.e., data transfer to third parties (M = 4.9; SD = 0.8), self-funded finance (M = 4.7; SD = 1.0), restriction of privacy (M = 4.7; SD = 0.8), and feeling of surveillance (M = 4.6; SD = 1.1)). Further, slight agreements were found for single aspects (e.g., less human contact (M = 4.0; SD = 1.3) and loss of control (M = 3.7; SD = 1.3)). Even Cluster 3 slightly rejected less self-determination (M = 3.4; SD = 1.2) and deficient aesthetics (M = 3.2; SD = 1.0) to be “real” barriers of technology usage.

Similar to the benefit cluster, a more heterogeneous evaluation pattern was found for Cluster 2: Data transfer to third parties (M = 3.6; SD = 1.0), self-funded finance (M = 3.5; SD = 1.1), and fear of data abuse (M = 3.5; SD = 1.1) represented the barriers with the comparatively highest – but still nearly neutral – evaluations, while all other barriers were slightly (e.g., feeling of surveillance (M = 3.1; SD = 1.0)) to moderately (e.g., less self-determination (M = 2.4; SD = 0.9)) rejected to be real barriers of using ultrasonic whistles in home care.

5 Discussion

In the following section, the study’s insights are discussed with regard to previous research in the field of AAL, technology acceptance, and aging. In addition, limitations of the study and ideas for future work are outlined.

5.1 Interpreting Perceptions of Aging, Benefits, and Barriers

This study’s aim was to achieve deeper insights into the assessment of ultrasonic whistles in home care, with special regard to older users’ benefit and barrier perception, as the risk for health restrictions and care needs increase with age. Though, commonly referred to as “the elderly”, our study showed that older people represent a heterogeneous user group with subjective aging concepts and visions of life. As new insights, the analysis of evaluation patterns proved an influence of attitudes towards aging on the decision to adopt or reject home care assistance.

In general, the obtained results revealed that the wish to grow old at home was commonly high, confirming corresponding research in the field of aging in place [13] and the importance of AAL studies. The majority of participants had only little experience with AAL technologies and systems (except for blood pressure monitors), presumably, as they were in good health. Overall, attitudes towards aging were positive, indicating an optimistic age frame regardless of predominant age stereotypes, such as of “the old and frail” (cf. [34]). On closer regard to the user characteristics, it was found that health status was related to the attitude towards aging. In detail, healthy participants shared rather positive concepts and expectations of aging, such as social inclusion, active lifestyle, and relaxed mood. In return, ill participants tended to agree more strongly with negative attitudes, such as decreasing health, being less fit and lively, which can be explained by negative experiences they have already made in terms of care dependency, acute and/or chronic diseases. Interestingly, neither gender nor age correlated with the attitude towards aging. Since in this context, personal experience (e.g. through health restrictions) was obviously more decisive, a rethinking of age and aging is required to meet individual needs of an elderly society, especially when it comes to how people imagine and perceive their lives in old age.

Considering the use of ultrasonic whistles as a new assistive device in home care, evaluation patterns were generally positive. With special attention given to the perception of benefits and barriers, an increased feeling of safety (as in many other AAL contexts [32, 42]) as well as independence from electricity and batteries (as a core feature in the present scenario) were considered as major advantages within the whole sample, whereas particularly the fear of data abuse restricted the adoption of ultrasonic whistles, emphasizing the importance of transparency and users’ trust in the monitoring system as essential acceptance factors. Besides, potential users were disconcerted by the self-funded finance, which may be explained against the background of an increasing poverty among the elderly [33].

With regard to effects of user diversity, we identified groups of “Adopter”, “Undecided”, and “Rejecter” in both evaluation contexts (benefits and barriers), summarized as follows: While the Adopters agreed with the benefits and rejected the barriers more strongly, the Rejecters disapproved of the benefits and supported the barriers, while the Undecided did not express a clear opinion in either context. Overall, the results showed a distinct intention to use the ultrasonic whistle in home care (which was highest for Adopters) as well as an influence of gender and the attitude towards aging on the perception of benefits and barriers. It was particularly surprising that people who did not appreciate benefits of using ultrasonic whistles (the “Rejecter”), had a comparatively very positive attitude towards aging, which may be related to an intrinsic drive for independence and autonomy, regardless of technology use. Hence, with regard to further research, the handling and perception of aging should be focused instead of the consideration of “age groups”.

5.2 Limitations and Outlook

Besides new insights into evaluation patterns regarding benefits and barriers of assisting technology and their relationships with different user factors (age and attitude towards aging), there are some limitations of the current study, which should be considered for future work in this research field.

As one methodological limitation, a cluster analysis was used to identify user groups differing in their perception of benefits and barriers. The cluster analysis presents only one approach to investigate user diversity impacts. In order to gain deeper insights into the relevance of user diversity, future research should aim an investigation of standard deviation distributions comparing the whole sample and the clusters. Besides this approach, future studies should investigate other relevant user factors such as attitude towards care and handling of aging.

Further, the knowledge about relationships between benefits and barriers is limited due to isolated evaluation of benefit items on the one and barrier items on the other hand. Current and future work therefore focuses on other approaches such as conjoint analyses [50] in which real life decisions, e.g., considering several benefits and barriers of technology usage can be simulated.

Besides scenario-based approaches, future studies should aim for investigations of the described AAL technology based on ultrasonic whistles in real life settings. This is of major importance as previous research has already shown that the applied methodology probably effects an underestimation of potential benefits and an overestimation of potential barriers [45]. Thus, future studies should aim for hands-on evaluations of the described AAL technology considering diverse user groups.

Another aspect refers to fact that the current study was conducted in Germany and represents a perspective of one single country. In particular with regard to perception of aging and care, other countries and cultures will probably have diverse attitudes and handlings of aging due to different family structures, (feelings of) responsibility, and diverse health care systems. Future studies will therefore focus on cross-national and cross-cultural comparisons of attitudes towards as well as handling of aging and care and their potential relationships with technology acceptance.

With regard to the sample, the sample size was adequate – in particular considering the fact that people aged 50 years and older were under study. While gender was equally spread, the educational level of the sample was above average [48]. Thus, future studies should investigate a more diverse sample with a broader range of educational levels (higher proportions of people with lower education levels) and its potential impact on evaluation patterns of benefits and barriers.