Harris Friedman and the Science of Transpersonal Psychology

I'm deep in my final paper for my independent study, so once again I'm posting part of a writeup for the research I've done along the way. Harris Friedman and the Science of Transpersonal Psychology © 2025 by Kimberly Israel is licensed under CC BY-NC 4.0

Romanticism, Scientism, and Constructivism

Harris Friedman advocates for transpersonal psychology to be circumscribed as a scientific field, suggesting that nonscientific approaches could legitimately belong to “transpersonal studies” but not “transpersonal psychology” (Friedman, 2002). He argues that psychology is generally treated as a science, that transpersonal psychology was originally developed along those scientific lines, and that using the word “psychology” to define the field carries an expectation of scientific methodology, particularly in clinical settings. He describes three major attitudes that diminish the scientific reputation of the field: romanticism, scientism, and constructivism.

 

Friedman (2005) describes romanticism as “rejection of rationality, fascination for the so-called exotic, erosion of all basis for discriminating among truth claims, fixation of idyllic images regarding humanity's relationship with nature, and attributions of supernatural claims without evidentiary support.” Examples include using astrology in a clinical practice or interpreting Eastern religious concepts as corresponding to particular states of consciousness (Friedman, 2002). Indeed, he demonstrates the issue quite succinctly in a non-paper in which he proposes to describe “all cogent scientific conceptualizations of the non-dual” (Friedman, 2018a) and presents the reader with a blank page. The abstract to the “article” explains that characterization of psychological states as non-dual depends on metaphysical constructs, which cannot be scientifically evaluated.

 

Friedman (2002) goes on to say that scientism is more of a concern outside the field than within; it is characterized by a narrow conception of what can and should be studied using scientific methods and frequently carries the assumption that romanticism is all transpersonal psychology has to offer. Transpersonal psychology is practically taboo in conventional psychology departments (Friedman, 2018b), possibly due to scientistic prejudice.

 

Constructivism, meanwhile, is the extreme postmodern view that because all human knowledge-building is influenced by culture and subject to bias and blind spots, no meaningful concept of reality is possible. While recognition of the limits of objectivity is certainly useful, science cannot proceed without some sense that methodology matters, that evidence means something beyond personal preference (Friedman, 2002).

 

Of course, much of the subject matter important to transpersonal psychology is outside the realm of science: transcendence, divinity, and nonduality are metaphysical concepts that cannot be directly probed. Science can, however, explore areas such as the effect of subjectively transcendent experiences on people’s lives or the influence of culture on one’s concept of transcendence. We can study the “phenomena,” the material available to our senses, including reports of others’ experience, without claiming access to the “noumena,” the things in themselves, such as the ontological validity of subjective experience (Friedman, 2002). Although Friedman takes a strong stance in favor of transpersonal psychology as a science, he also accepts that nonscientific sources, such as spiritual teachers or traditions, may well be valuable sources of knowledge in one’s personal life. Although Friedman is a psychologist rather than a paleontologist, his stance seems to approximate Gould’s (1997) position of “nonoverlapping magisteria.”

Western Romanticism Towards Aikido

As a practitioner of aikido, Friedman (2005) uses it as a case study of the kind of romanticism he finds objectionable in the transpersonal field. He begins by noting that the roots of the martial art are in the training needed for a disarmed samurai to have a chance of surviving against his opponents long enough to escape. The character traits of courage and present-moment focus emphasized by the practice would also have been specifically adaptive in combat conditions.

 

Friedman notes that in cross-cultural situations, Westerners interested in transpersonal systems frequently romanticize traditional lines of authority and teaching styles, assuming without evidence that because the tradition demonstrates some benefits, it is correct in all things. As an example, he refers to the primary global school of aikido, leadership of which has been handed down from father to son. The current head of the school is the grandson of the man who developed much of modern aikido but is young and inexperienced. Friedman sees unquestioning acceptance of the current leader’s qualifications as a form of romanticism.

 

He also challenges the tendency to romanticize Japan as the spiritual home or truest expression of aikido simply because the practice developed there: today, aikido has many more practitioners outside Japan, where baseball is far more popular. Finally, he explains that the effectiveness of aikido can be understood without reference to the supernatural. The martial art does take a transpersonal perspective of viewing self and opponent as one system, and Friedman argues that doing so results in greater attunement to the opponent and a more effective defense. Impressive feats like the “unbendable arm” don’t rely on a conceptually nebulous “energy” but on physiological relaxation of opposing muscles and the prevention of inhibitory nerve impulses through clarity of intent (Friedman, 2005).

Image credit: Christelle Fillonneau

https://commons.wikimedia.org/wiki/File:Nikyo_omote.jpeg

(This is not an image of Friedman, just a representative image of people practicing aikido)

                                                                        References

Friedman, H. (2002). Transpersonal psychology as a scientific field. International Journal of Transpersonal Studies, 21(1), 175-187.

Friedman, H. (2005). Problems of romanticism in transpersonal psychology: a case study of aikido. The Humanistic Psychologist, 33(1), 3-24.

Friedman, H.L. (2018a). An explication of all cogent scientific conceptualizations regarding the non-dual: finding nothing to write. International Journal of Transpersonal Studies, 37(2), 116-118.

Friedman, H.L. (2018b). Transpersonal psychology as a heterodox approach to psychological science: focus on the construct of self-expansiveness and its measure. Archives of Scientific Psychology 6, 230-242.

Gould, S.J. (1997). Nonoverlapping magisteria. Natural History, 106, 16-22.

Buriro, Z. A., Nawaz, H. I., & Asif, M. (2025). FROM EMPHASIS TO MOCKERY: THE MULTIFUNCTIONAL ROLE OF REDUPLICATION IN SINDHI. Journal of Applied Linguistics and TESOL (JALT), 8(2), 959-969.

 What They Did

The researchers studied the linguistic role of word and sound reduplication in Sindhi, a major language of Pakistan, particularly the province of Sindh. They collected 31 instances of reduplication from social settings and analyzed their contextual meaning with the assistance of native speakers. Reduplication of full words often carries emotional content. Saying گهم گهم (‘ghum ghum’) is a reference to wandering around and can be used affectionately in the sense of a parent telling a child to go have fun. The phrase کل کل (‘khil khil’) can refer to someone laughing happily, but in response to mocking, the meaning is more akin to “You’re laughing now, but my time will come.”

Sound reduplications may be rhymes, near rhymes, or alliterations. They frequently carry information about the situational context. Saying وٺ سٺ (‘wath sath’) refers to being in a hurry, particularly for handling complex plans such as wedding preparations. The phrase پويتياگتي (‘agte poete’) literally means “back and forth” and socially refers to a situation in which another person won’t make a commitment. When people say سهانگو مهانگ (‘mahango sahango’), which translates as “costly but necessary,” it’s generally a comment on rising costs of necessary items and the fact that they have to be purchased anyway.

Sinhi speakers also use reduplication of words that have no literal meaning. The phrase هور هور (‘horr horr’) is used to mock someone in an exaggerated way, while تر تر (‘tur tur’) is an angry warning that the opponent in a confrontation had better leave.

 

Further Exploration

I use reduplication in my own communication. My spouse and I often want to text “k” as a shorthand for “Ok” but somehow “k” on its own feels abrupt or dismissive, so we’ve taken to using “kk.” This defeats the purpose of shortening “Ok,” but it’s also developed a different feeling: “kk” carries a sense of being on the same wavelength, of being in an activity together, even if we’re carrying out different tasks. “Ok,” on the other hand, has a sense of accepting information or instruction from the other person.

Similarly, if I text “neat neat” in response to a story or observation, that means I’m engaged and open to hearing more, whereas “neat” without the repetition has more of a sense of “I’m happy for you and want to be supportive but am not necessarily interested for myself.” Of course, these examples are highly idiosyncratic, but many other examples of reduplication in English will likely be familiar (see https://daily.jstor.org/the-nitty-gritty-on-reduplication-so-good-you-have-to-say-it-twice/).

In the sentence “I’ll make the tuna salad and you make the salad-salad,” the repetition indicates that the second salad is closer to the central concept of a salad. Sound reduplications in English are often informal and nonliteral. The phrase “loosey-goosey,” for example, seems to have a sense of being unstructured almost to the point of falling apart, which may indicate negligence or flexibility, depending on the situation, but has nothing to do with geese. Lots of other languages also use reduplication, but that’s a rabbit hole for another day!

Image credit: Baba66

https://simple.m.wikipedia.org/wiki/File:Flag_of_Sindh.svg

Hunter, Holly, Grace Blackburn, Benjamin J. Ashton, and Amanda R. Ridley. "Group size affects spontaneous quantity discrimination performance in wild Western Australian magpies (Gymnorhina tibicen dorsalis)." Animal Cognition 28, no. 1 (2025):

What They Did

The researchers studied the ability of wild Western Australian magpies to distinguish quantities. The magpies live in groups of 3 to 15 in urban semi-natural areas and are accustomed to humans. Individual magpies were separated from their group, either by waiting for them to wander off naturally or by distracting the other group members. The bird under study was then presented with a randomized sequence of choices between two boards: one with two strips of cheese and the other with two, three, four, or five strips. Over the course of the experiment, 42 birds were tested, each being offered the four choices 15 times on separate days.

 The researchers found that the birds chose the larger amount of food more than half the time, with better performance correlated with greater differences between the amounts. They also found that birds that lived in smaller groups were more likely to choose five strips of cheese over two, but the group size had no effect for the other combinations. The correlation between “correct” choice likelihood and difference between the choices suggests that the birds decide based on ratio rather than absolute number, with the smallest ratio (i.e. 2:5) easiest to detect.

The researchers also propose two hypotheses for the effect of group size. Smaller groups may offer less protection in intergroup conflicts, making it important to compare the size of rival group. Smaller groups also have fewer individuals watching for predators, so it’s more important to maximize the benefit of limited foraging time.

 

Further Exploration

The researchers describe two cognitive systems animals use to process quantity information: the object-file system tracks each object and works for small numbers, while the approximate number system provides a general idea of which group is larger. This seems to be the case for humans too. Automatically knowing how many objects are in a group in called subitizing (see https://hechingerreport.org/proof-points-subitizing/). Perceptual subitizing means seeing the number of objects “all at once.” For humans, the maximum is typically 4 to 6 objects.

Larger numbers, however, can be subitized by mentally dividing the array into groups and subitizing the number in each group, such as seeing three groups of four and knowing there are 12 objects without thinking about counting or multiplication. This process is called conceptual subitizing. Subitizing sounds as if it might be analogous to the object-file system described in animal cognition, and of course humans also seem to have an approximate number system. We can tell which group of items contains more, and we’re better at it if there’s a greater difference between them.

Humans can also count one by one, as long as we have the patience for. A lot of animals deal with quantity in a lot of different ways (see https://www.quantamagazine.org/animals-can-count-and-use-zero-how-far-does-their-number-sense-go-20210809/), but I haven’t seen any evidence that they can count symbolically and indefinitely the way humans do. It would also be interesting to see how animals handle number when the objects are dissimilar or when distractor objects are included, but that’s a rabbit hole for another day!    

Image credit: D. Gordon E. Robertson

https://commons.wikimedia.org/wiki/File:Western_Magpie,_Perth.jpg

Testoni, I., Vischio, A., Ciappa, C., Gentile, M., & De Vincenzo, C. (2025). Social Psychological and Spiritual Discomfort: Legitimization of the Need for Transcendence and Psychological Listening. Pastoral Psychology, 1-14.

 What They Did

Working through a spiritual support organization, the researchers recruited 21 adults who had sought help from a priest exorcist (though none had actual exorcisms performed). Participants responded to questionnaires about personal well-being, coping methods, childhood trauma, propensity for fantasy, and conceptualizations of death. Eight of the respondents also participated in semi-structured interviews about their experience.

 Statistical analysis of the questionnaire responses showed that use of religion and transcendence as coping strategies was correlated with lower psychological distress. Conceptualization of death as the end of one’s existence, on the other hand, was correlated with greater psychological distress and inversely correlated with both the use of religion as a coping method and the propensity for fantasy. Finally, childhood emotional neglect was correlated with the use of avoidance as a coping strategy.

The eight interviews revealed that the participants experienced existential distress, particularly around personal and family issues. Some reported feeling trapped and desperate for escape. Most of the participants had significant trauma in their childhoods, ranging from parental violence or severe parental mental illness to emotional neglect, even when some had attempted suicide themselves. Many participants were surprised at the compassion and understanding with which spiritual caregivers responded to their stories. They mentioned feelings of relief and comfort and described the importance of being deeply seen and heard in their suffering. Although participants saw their faith as an important source of clarity and stability, many also noted the importance of combining spiritual and psychological approaches, some working with both clergy and psychologists.

Further Exploration

Although the research findings are interesting, I don’t feel like they really address the question of why the participants sought assistance from spiritual figures rather than from mental health professions. About 90% of the participants said they were religious, and about half had seen a psychologist at some point. It’s not surprising that religious individuals might seek help from clergy, though I do wonder what motivated the other 10% to seek not just a priest but one trained in exorcism.

This study was conducted in Italy, and I don’t know what the statistics are there, but in the United States, about 150 Roman Catholic priests are trained in exorcism (see https://thenationaldesk.com/news/americas-news-now/vatican-to-hold-training-next-month-as-demand-for-exorcism-continues-to-rise-catholic-church-prayer-ritual-priests-internation-association-of-exorcists-paranormal-supernatural-psychiatry-mental-health) out of about 37,000 priests total (see https://www.usccb.org/offices/public-affairs/clergy-and-religious), so less than 1% of U.S. Roman Catholic priests are exorcists. As noted above, none of the research participants actually went through an exorcism ritual, which is also unsurprising: according to the National Desk article above, only 1 in every 5000 people who present as possible cases of possession are confirmed as such by religious officials.

The National Desk article dates from 2023 and refers to an increase in requests for exorcisms, but that increase has been reported since at least 2014 (see https://www.vice.com/en/article/why-catholic-exorcists-are-seeing-an-uptick-in-requests/). Some suggest that fictional representations have increased interest. The researchers who conducted this study also mention that some consider possession in the Christian sense to be a culture-bound psychological syndrome. It would be interesting to compare possession with other culture-bound syndromes, but that’s a rabbit hole for another day!

Public domain image

https://commons.wikimedia.org/wiki/File:Folio_166r_-_The_Exorcism.jpg

Zivanovic, Goran, Concepció Arenas, and Francesc Mestres. "Temporal and habitat adaptations in Drosophila subobscura populations: changes in chromosomal inversions." Genetica 153, no. 1 (2025): 16.

 What They Did

In 2023, the researchers collected Drosophila subobscura fruit flies from Jastrebac Mountain in Serbia, revisiting oak and beech forest locations that had been previous collection sites in 1990 for the oak forest and in 1990, 1993, and 1994 for the beech forest. Male flies from the 2023 collection and their descendants were crossed with flies from a reference strain. The researchers dissected at least eight larvae from each cross to examine their chromosomes. In particular, they looked at the different patterns of inversions, areas where part of the original chromosome was detached, flipped, and replaced. (For example, a nucleotide sequence of TGATTCGG might change to AGTTTCGG).

Previous research had identified many D. subobscura chromosomal inversions as cold-adapted, warm-adapted, or not thermally adapted. Therefore, the researchers were able to quantify the degree of imbalance in warm- or cold-adapted chromosomes for each collection site. Multivariate analysis showed that some of the chromosomal variation among groups of fruit flies depended on time, with those from the 2023 oak and beech site similar to each other, those from the 1993 and 1994 beech sites differing, and those from the 1990 oak and beech sites differing even more.

Among the flies in the beech forest, the imbalance towards warm-adapted chromosomes increased from 1990 to 1994 but did not change from 1994 to 2023, suggesting that the degree of adaptation reached its maximum in 1994. The flies at the oak site did not show a significant change in the degree of adaptation between 1990 and 2023.

 

Further Exploration

A good number of inversions have been in the human genome for a while and aren’t reported in laboratory DNA analysis because they’re considered natural variants. Since this information came from a document about chromosomal disorders (see https://rarechromo.org/media/information/Other%20Topics/Inversions%20FTNW.pdf), I assume the context is a DNA analysis to find out if one has any chromosomal issues that might affect fertility or the health of one’s children.

Most of the time, chromosomal inversions don’t cause any problems. This might be because they’re usually less than 1000 base pairs (see https://pmc.ncbi.nlm.nih.gov/articles/PMC2946949/). Since most human DNA doesn’t code for proteins, an inversion of only a few hundred base pairs might not affect protein coding at all. At the same time, other functions have been found for some of that non-coding DNA, and I wonder what effects inversions would have on other functions (see https://www.quantamagazine.org/the-complex-truth-about-junk-dna-20210901/). Sections of DNA with inversions are a lot less likely to recombine with non-inverted analogous chromosomes during meiosis, so there’s more tendency for genes in or near the inversion to be inherited together. This is also part of how sex chromosomes work: inversions make the Y chromosome largely unable to recombine with the X chromosome.

It appears that the process that generates some of the inversions in D. subobscura also results in additional copies of some segments of DNA. These extra copies might provide an advantage in tolerating different climate conditions (see https://www.nature.com/articles/srep30715). I’d love to know exactly how the inversions affect fruit fly climate adaption, but that’s a rabbit hole for another day!

Image credit: Martin Cooper (adapted from original collage image to show only the adult fruit fly).

https://commons.wikimedia.org/wiki/File:Drosophila_(Sophophora)_subobscura_(male)_collage.jpg

Nature-Based Spirituality, East and West

Today's post is once again taken from my independent study work. Nature-Based Spirituality, East and West © 2025 by Kimberly Israel is licensed under CC BY-NC 4.0

Spiritual Ecosystem Services

Nakadi (2023) addresses the psychological importance of nature with his conception of “spiritual ecosystem services.” In particular, he examines the ecological factors that contribute to large trees being given unique names and considered sacred. Using a database of over 39,000 trees in Japan with circumferences of at least 3 meters, he looked for correlations among tree size, tree age, average temperature, average annual precipitation, elevation, latitude, likelihood of a tree having a unique name, and likelihood of a tree being considered sacred. The largest trees tended to be older and grow in areas with more precipitation. They were also found in cooler areas at lower elevation and lower latitude.

 

Unsurprisingly, larger and older trees were more likely to have names and be considered sacred. The likelihood of naming and sacred status, however, were also inversely correlated with precipitation. Nakadi speculates that this may be because tree-worship in Japan historically included prayers for rain, particularly when the success of drought-sensitive rice crops was a matter of life and death. Some of the names given to trees also relate to their perceived spiritual connection to the rain.

 

While both naming and sacred status were related to precipitation, only the likelihood of being given a name was correlated with elevation. Nakadi suggests that large trees at higher elevations are particularly likely to be seen from a distance and to serve as landmarks and may therefore be named for practical purposes even if they are not considered sacred. As Nakadi himself points out, this study addresses only one component of the relationship between spiritual meaning and underlying ecology in one culture. Much more research is needed to understand the provisioning of “spiritual ecosystem services” in other contexts so as to prevent the loss of important components of human well-being.

 

Neo-Pagan Spirituality

 

Modern druidry is frequently classified as a form of neo-pagan spirituality, and indeed several of the same people were involved in the development of both Wicca and modern druidry (OBOD, n.d.). Therefore, research on present-day pagan spiritual experience may generalize at least somewhat to modern druid spirituality as well. Sonnex et al. (2022) discuss the psychological benefits of pagan practice in relation to liminality and eudaimonia.

 

Many pagan workings involve the casting of a circle to create a liminal space between the mundane and magical or spiritual realms (Sonnex et al., 2022), a practice also used in modern druidry (OBOD, n.d.). According to Sonnex et al., the pagan activities within the circle are generally meant to access and direct “energy” towards the chosen purpose. Engaging the senses through symbolism, props, and costumes helps create a sense of immersion and increases the liminality of the working. As participants imaginatively identify with the working, the boundaries between conscious and unconscious, reason and emotion become blurred. Sonnex et al. note that although pagan workings may have an element of amateur theater, the participants find them to be spiritually meaningful.

 

Furthermore, they argue that pagan spirituality promotes well-being in the eudaimonic sense of living well, not only in the hedonic sense of feeling good. Many pagans consider personal growth to be the most important part of their workings. They see their activities as promoting empowerment and constructive acceptance of life changes. Sonnex et al. cite two examples of workings: one focusing on a young woman who wanted to confidently take on adult roles in her family and one centered on an older woman who wanted to accept aging. In both cases, the purpose was not to change the physical world but to help the participants grow to meet the challenges of a new stage of life: the workings metaphorically enact the needed transformations.

Image credit: John William Waterhouse (public domain)

https://commons.wikimedia.org/wiki/File:The_magic_circle,_by_John_William_Waterhouse.jpg

References

Nakadai, R. (2023). Macroecological processes drive spiritual ecosystem services obtained from giant trees. Nature Plants, 9, 209-213.

OBOD. (n.d.) The origins of Wicca & Druidry. Order of Bards, Ovates & Druids. https://druidry.org/druid-way/other-paths/wicca-druidcraft/origins-wicca-druidry

Sonnex, C., Roe, C.A., & Roxburgh, E.C. (2022). Flow, liminality, and eudaimonia: pagan ritual practice as a gateway to a life with meaning. Journal of Humanistic Psychology, 62(2), 233-256.

Passmore and Krauss on the Role of Nature in Meaning-Making

Today's post is once again from my independent study work, primarily summarizing some of the key points in a journal article I found really valuable. Passmore and Krauss on the Role of Nature in Meaning-Making © 2025 by Kimberly Israel is licensed under CC BY-NC 4.0

Although spiritual paths such as modern druidry emphasize connection with nature, the role of nature in meaning-making is certainly not unique to druids. In a review article, Passmore and Krauss (2023) discuss the research on nature as a source of meaning for people in general. They focus on a tripartite model of meaning, which breaks the concept into coherence, purpose, and significance. They also refer to work on experiential appreciation as an additional potential component of meaning.

 People can find a sense of coherence in the patterns and cycles of nature, positioning their own life and its changes in a broader context. In her book on secular meaning-making, Sasha Sagan (2019), notes that people around the world celebrate astronomy and biology: phases of the moon; solstices and equinoxes; changes in seasons; planting and harvest; birth, growth, and death. Attending to the change and repetition in nature can provide a larger perspective on life and increase a feeling that the universe makes sense (Passmore & Krauss, 2023).

 

Nature can be a source of inspiration, increasing one’s feeling of purpose. Passmore and Krauss note that research suggests that time in nature enhances self-reflection, which is necessary for developing a conscious sense of purpose. Furthermore, many people find purpose in activities that engage or benefit nature, from gardening to environmental activism. These activities provide channels for the individual to invest effort in something larger than themselves.  Purposeful action can enhance a person’s sense of significance by allowing them to see that they make a difference.

 

The experiences of connection and embodiment in nature also increase the feeling of significance. Passmore and Krauss refer to studies showing a correlation between green space and social cohesion, as well as evidence that exposure to awe-inspiring aspects of nature increases the feeling of social connectedness. Furthermore, even attention to components nature encountered in daily life increases the sense of “transcendent connectedness.” The awareness of being part of something, whether a social group or the universe as a whole, seems to increase the sense of significance. This insight seems to run counter, however, to the common descriptions of feeling small or unimportant relative to the ocean or the galaxy, and further research may be needed to unpack this apparent paradox.

 

Passmore and Krauss note that some research suggests experiential appreciation as a fourth component of meaning. Experiential appreciation involves a strong sense of valuing and being absorbed in the present moment. The authors mention several theories that suggest biological underpinnings for experiential appreciation in relation to nature. The Biophilia Hypothesis, developed by E.O. Wilson in the 1980s, suggests that human beings evolved to form emotional connections with nonhuman nature (Gaekwad et al., 2022). 

The Attention Restoration Theory, meanwhile, proposes that natural environments provide restoration from “directed attention fatigue” by gently engaging attention without requiring effort from the viewer and allowing space for the mind to wander (Kaplan, 1995). The research of Joye et al. (2016) supports the idea that the fractal quality (i.e. scale-invariant self-similarity) of natural objects means they take less cognitive effort to visually process, such that people display greater “perceptual fluency” in natural environments.

Image credit: Hubert Stoffels

https://commons.wikimedia.org/wiki/File:Jonathan%27s_Run_Falls.jpg

References

 

Gaekwad, J.S., Moslehian, A.S., Roös, P.B., & Walker, A. (2022). A meta-analysis of emotional evidence for the Biophilia Hypothesis and implications for biophilic design. Frontiers in Psychology, 13, 750245.

 

Joye, Y., Steg, L., Unal, A.B., & Pals, R. (2016). When complex is easy on the mind: internal representation of visual information in complex objects is a source of perceptual fluency. Journal of Experimental Psychology: Human Perception and Performance, 42(1), 103-114.

 

Kaplan, S. (1995). The restorative benefits of nature: toward an integrative framework. Journal of Environmental Psychology, 15, 169-182.

 

Passmore, H.-A., & Krause, A.N. (2023). The beyond-human natural world: providing meaning and making meaning. International Journal of Environmental Research and Public Health, 20, 6170.

Sagan, S. (2019). For small creatures such as we. Putnam Adult (Hc).