Ideas guided by astrological principles have existed in just about every human civilization, going back several millennia before the birth of Christ (Tester, 1989). The basic underlying concept is that the positioning of celestial objects at a time that is of significance to the individual influences fundamental aspects of their personality, motivations, wants, and needs. As a consequence, the astrologer, an individual trained to calculate the position of relevant objects and make an accurate reading will be able to make predictions or recommendations positively influencing individual well-being. Astrology represented an essential part of the culture of several ancient civilizations and was until comparatively recently considered to be a science. Western astrology goes back several centuries prior to the birth of Christ, with the birth of modern astrology being attributed to Ptolemy’s Tetrabiblos, considered to be the earliest comprehensive textbook on astrology (Woolfolk, 2006). A key characteristic of western astrology is its horoscopic nature, implying that predictions can be made based on the positioning of the planets, and stars at a given point in time, typically at the individual’s time of birth. From the end of the Roman Empire until today, the popularity of astrology among the general public in what is today the western world has varied considerably. It experienced a considerable resurgence among both intellectuals and the general public during the Renaissance, while it came under increasing scrutiny during the age of Enlightenment. This was largely due to the scientific discoveries of—among others—Copernicus, Galileo, Kepler, and Newton, displacing the Earth from the center of the solar system as well as introducing a new understanding of physics.
In recent centuries, however, astrology has experienced a revival, again becoming widely popular and used primarily for entertainment, but in certain cases also with the intent to obtain guidance. Individuals in western countries are exposed to weekly or monthly horoscopes in just about every printed newspaper. Bogart (1989) reports that about 85% of American newspapers included an astrology column in 1987, a figure that is most likely very similar today. In addition, there is a plethora of horoscopes or other information related to astrology available on the internet as well as in books, for those who consider themselves to be more than a casual consumer. While data is scarce, and it is difficult to directly compare across different studies, the persistence of horoscopes in popular media confirms that the general public’s consumption of astrology remains high. Maitre (1966) examined a sample of Parisians, showing that about 30% of those surveyed reported to be consumers of astrology. Some 20 years later, in the UK, in 1988, Bauer and Durant (1997) report that 73% of the adult population read horoscopes or astrology reports, with the majority doing so “fairly often” or “often.” For the USA, in 1999, about half of the population surveyed for the 2000 Science and Engineering Indicators report claimed that they read their horoscope at least occasionally (National Science Board, 2000).
Existing data suggests that the majority of individuals who read horoscopes do so primarily for the entertainment value of it, with less than one of ten individuals in the UK, claiming that they take astrology reports “seriously” or “fairly seriously” (Bauer & Durant, 1997). More recent statistics from many different countries, however, indicate that the share of the population who look to horoscopes not only for entertainment but also believe them to have scientific value is considerably higher than what is suggested by the figure from the UK. A 2005 Gallup survey in the USA, for example, revealed that one-quarter of those interviewed believed that “astrology (...) can affect people’s lives” (Lyons, 2005). This remains true even more recently, with 42% of Americans in 2012 claiming astrology is either “sort of scientific” or “very scientific” (National Science Board, 2014). Indeed, the same survey reports that the share rejecting astrology as “not at all scientific” in 2012 was at its lowest point since 1983. Another interesting observation from the US survey that has also been reported from Europe (Allum, 2011), is that there is a negative relationship between age and believing in astrology.
In Europe, net of a range of individual-level characteristics, beliefs in astrology are shown to vary substantially across countries. While the results display no clear geographical pattern, Sweden emerges as one of the countries with the lowest share of individuals believing in astrology. Indeed, the 2015 wave of a Swedish attitude survey indicated that only 13% were leaning toward believing in astrology, with only 3% expressing a firm belief that “the positioning of the planet at the time of the individual’s birth influences their daily lives and personality” (Foreningen Vetenskap och Folkbildning, 2015). Further corroborating evidence for the comparatively low level of belief in astrology in Sweden comes from the 2005 Special Eurobarometer, surveying individuals in 25 EU countries. Overall, the survey found that 41% of those surveyed gave astrology a score of 4 out of 5 when asked to assess how scientific it is. This study, along with others, have however indicated that individuals tend to conflate astrology and astronomy, indeed suggested by a substantially smaller share who assesses the scientific qualities of horoscopes as high, only amounting to 13% (see also Allum, 2011).
Theoretical framework
The theoretical foundation upon which astrology predicts the relationship compatibility of two individuals is based on a belief that the position of celestial bodies at the time of birth has a profound influence on the personality (Orion, 2007). While the theory is rather clear about which characteristic that is influenced by which celestial body and about the strength of this influence depending on its position at the time of birth, it is less clear about the mechanism which produces the predicted outcome. The most comprehensive (and, arguably, precise) astrological reading is referred to as natal astrology, and requires information not only on the individual’s time of birth but also the geographical location in order to thoroughly assess a range of different characteristics (Oken, 1988). This is needed in order to not only identify the location of the sun at the time of birth but also the location of several other celestial bodies, each associated with their unique influence on the individual’s personality. All ten celestial bodies examined, from the Sun and the Moon to Venus and Uranus alternate between the twelve familiar different sun signs, at varying intervals, and with differing implications for how the individual’s associated traits are expressed (Woolfolk, 2006). For example, if the planet Venus, associated with ruling the force of attraction, sexual and otherwise, is in Cancer at the time of the individual’s birth, the individual is predicted to be a nester, whereas when it is in Scorpio, the love life tends to be stormier. The sign of the moon—describing emotional reactions, changes every 2-3 days, whereas those of more distant planets change much less frequently (Orion, 2007).
The astrologer also needs to address the twelve so-called houses, representing another dimension of authority over specific areas of interest of the individual’s life. In terms of their areas of influence, the fifth house, for example, influences the individual’s experience in the area of romance and children, whereas the seventh house influences marriage and partnerships. The ascendant, the rising sign or the first house, is the sign that was rising over the eastern horizon at the moment of the individual’s birth, rotating overall twelve zodiac signs over the course of 24 h (once approximately every 2 h), implying that, for every day, each sign is the rising sign during a 24 h period. The outcome of this is that if an individual whose sun sign is Aries is born while Aries is the ascendant, the resulting personality traits will be courageous, ambitious, and impulsive. Having found the ascendant, assigning the remaining eleven houses is straightforward, since this follows the sign chart. Thus, if the ascendant is Gemini, the second house will be Cancer, followed by Leo and so forth, until all twelve houses are occupied.
While a full natal reading requires more comprehensive information and thereby also is argued to provide a more precise astrological reading, the majority of horoscopes consumed by the general public are represented by a sun-sign astrological reading. This type of horoscope bases the astrological prediction solely on the position of the sun on the day an individual was born, without accounting for the position of the remaining nine celestial bodies or the houses. Despite its comparatively greater simplicity, astrologers widely claim sun sign horoscopes to be highly informative regarding matters such as relationships and career, and these represent what is normally encountered in magazines and newspapers (Crowe, 1990). The twelve sun signs are argued to be distinguishable according to three different qualities, which together form the basis for the individual’s essential personality traits. The first dimension divides the sun signs into two categories, the positive (masculine) and the negative (feminine) signs. Individuals born under the positive signs are believed to be more extroverted, objective, and assertive, whereas the negative signs are associated with the opposite qualities, namely introversion, subjectivity, and being receptive (Hamilton, 2001). The next dimension is referred to as a sun sign’s modality, dividing the sun signs into three categories which describe differences in individuals’ forms of expression. Gemini, along with Virgo, Sagittarius, and Pisces, represent the mutable sun signs, considered to be flexible and versatile. In contrast, individuals belonging to the four fixed sun signs are focused and determined, whereas the last category, the four cardinal sun signs are enterprising, promoting change, and making things happen. The third and last dimension is represented by the elements, allocating each sign of the zodiac to one of the four elements: fire, earth, air, and water. Following the same logic as the previously discussed dimensions, the twelve sun signs are distributed evenly across the four elements, thus with three sun signs in each. The associated characteristics are informative about the individual’s character, with the air signs (Gemini, Libra, Aquarius) being strong both when it comes to intellect and sociability, whereas the corresponding strengths for the fire signs (Aries, Leo, Sagittarius) are vitality, excitement, and intensity. Taking the three dimensions together, each sun sign is represented by a unique combination of characteristics, allowing the astrologer to make predictions about essential features of the individual, in addition to determining which sun signs are the most compatible in romantic relationships (Orion, 2007).
Previous research
Despite the contemporary scientific community’s enduring skepticism toward astrology, frequently labeling it a pseudo-science (Thagard, 1978), there is a relative dearth of empirical studies examining its potential validity. Difficulties in evaluating the validity of astrology are intrinsically linked to predictions from horoscopes which are often very vague, making testable hypotheses difficult to formulate. Indeed, the vagueness of astrological predictions is likely to be a key reason for its persistent popularity among the general public, since individuals have a tendency to embrace unspecific (favorable) characterizations of themselves as accurate if they believe that they are the result of a systematic procedure and uniquely generated for them. This phenomenon is named the Barnum effect, and its relevance for astrology was first illustrated by Forer (1949) who conducted an experiment where he provided students with what they believed to carefully tailored personality evaluations. The evaluations handed out were, however, identical across all students, consisting of a rather general description of personality traits. The students’ high degree of agreement with said evaluations led Forer to conclude that the students’ behavior was consistent with the Barnum effect (see also Fichten & Sunerton, 1983).
Another feature linked to astrology is that of self-attribution, referring to how knowledge of one’s horoscope influences how one remembers experiences (Glick & Snyder, 1986; Munro & Munro, 2000). More specifically, an individual who reads in their daily horoscope that they will meet with some unfortunate event is likely to pay particular attention to situations that could be perceived as threatening or dangerous, thus, positively reinforcing a confirmation bias. Similarly, an individual who knows that they are supposed to be short-tempered because of their particular sun sign, will be more likely to remember behavior consistent with this description than someone displaying a similar behavior but whose horoscope says that they are patient. Related to this, Hamilton (2001) suggested that a key determinant of an individual’s acceptance of astrology is linked to the degree of favorability that it offers. As a consequence, astrology could affect an individual’s experience, not necessarily because the astrological prediction is correct, but because it influences how individuals perceive events. Clobert, Van Cappellen, Bourdon, and Cohen (2016) confirm this through showing that individuals subjected to a positive astrological reading not only interpreted ambiguous events in a more favorable light but also that it positively affected cognitive performance and creativity. Further support for the hypothesis that observed effects are driven by self-attribution is provided by the fact that effects were the strongest for individuals self-professing to believe in astrology (Hamilton, 2001).
The vast majority of the empirical research has focused on whether an individual’s displayed personality traits are consistent with those predicted by astrology, producing rather mixed results. One strand of literature has investigated to what extent individuals are able to accurately predict which out of two astrology readings—one actually made for them and one for another sign—applies to themselves, depending on their birth chart. The results have failed to confirm individuals’ ability to do so (Carlson, 1985; Culver & Ianna, 1988; Dean, 1987). Another number of papers have examined a fundamental prediction in astrology, namely that individuals born with the sun in a positive sign are more extroverted. Analyzing the personality scores of a comparatively large sample of individuals, Mayo, White, and Eysenck (1978) clearly found differences in extroversion scores that are consistent with astrological predictions. While a number of subsequent studies confirmed their findings (e.g., Fuzeau-Braesch, 1997; Jackson, 1979; Smithers & Cooper, 1978), several scholars indeed found that the relationship observed was driven by self-attribution. As an example, van Rooij (1994) shows that aforementioned personality differences can only be observed among individuals with prior knowledge about astrology, a result which mirrors the findings of Eysenck (1981) as well as the later studies by Hamilton (1995) and Chico and Lorenzo-Seva (2006).
To our knowledge, only a small number of previous studies have examined the influence of astrology on outcomes relating to matters of love and relationships. The earliest example is Silverman (1971), who analyzes marriage and divorce records from Michigan in 1967 and 1968. While being a rather rudimentary test of compatibility, using predictions from two named astrologers, the study fails to find any indications suggesting that the predictions of two independent astrologers are consistent with what is observed in the data. These findings were challenged by Sachs (1999), using data from Switzerland to examine the relationship between zodiac sign combinations and marriages, divorces as well as a selection of other outcomes. According to Sachs, among the 13 sun-sign pairs that displayed higher than expected marriage probabilities, 12 belonged to pairings that are deemed astrologically compatible. Another study, by Blackmore and Seebold (2001) found that women who are subjected to positive love advice through their horoscopes were observed with slightly elevated relationship scores, compared to women exposed to neutral advice. Effects were largest for women with greater belief in astrology, consistent with self-attribution. Lastly, Henningsen and Miller Henningsen (2013) examine a sample of married individuals, investigating to what extent the couple’s astrological compatibility is associated with the degree of marital satisfaction. While simultaneously controlling for individuals’ beliefs in astrology, thus attempting to cancel out the self-attribution influence, the study finds some support for astrological compatibility.