Humans are probably the only creature capable of shedding tears based on feelings.

In order to fathom human crying, psychologists from the Universities of Ulm and Sussex surveyed 720 people online about the reasons for emotional tears.

In another study, 91 subjects were asked to keep a daily diary.

The participants in the studies, members of the general public and students of both genders, had a mean age of 30.3 years.

In the journal "Motivation and Emotion", the scientists now divide human tears into five categories: loneliness, powerlessness, overwhelm, harmony and media consumption.

Hurt or fulfilled basic needs cause tears

The classification into these categories is based on the idea that emotional tears always occur when basic psychological needs are either not met or are very intensely satisfied, the researchers explain.

This is similar to basic biological needs - such as eating or sleeping - where frustration or satisfaction would also affect our subjective well-being.

Research has established the needs for “closeness” (to feel connected), “autonomy” (to be able to influence things) and “competence” (to be able to carry out something successfully) as central psychological basic needs.

The psychologists point out, for example, that the feeling of loneliness is caused by an unfulfilled need for closeness - and can thus lead to tears.

Tears flow "representatively"

Tears that flow because of lovesickness or homesickness are also counted in the same category.

On the other hand, tears that fell through an intensive satisfaction of the need for closeness - such as tears of joy at a wedding celebration - were classified in the harmony category.

As an example of tears due to impotence, the researchers describe the reaction to a death message.

Overload was often reported in the work context - tears fell, especially among younger people.

Every fourth reported episode in which emotional tears fell was placed in the media consumption category, which has some peculiarities in comparison.

The crying person is only indirectly affected and the tears flow "representatively" of an experience that happens to a character in a film or book that the person concerned empathizes with.

Both tears of joy and tears of sadness can flow, depending on whether it is a comedy or a drama, for example.

The emotional tears can be clearly distinguished from the so-called basal tears, which keep the eyes moist and protect them from drying out.

The researchers also left out tears as a reflex reaction to cold, wind or when cutting onions in their study.

The psychologists see the study as a basis for further research on the phenomenon of emotional tears.

So far, there has been a lack of knowledge about the influence tears have on whether one person supports another, says co-author Johannes Keller, head of the Department of Social Psychology at Ulm University.

The role of tears in mental illness is also largely unknown.

Identifying the five most common reasons for crying could therefore help to answer these questions in the future.