Trait

Trait (pronounced treyt or trey (now rare))

(1) A distinguishing characteristic or quality distinguishing a particular person or thing, especially of one's personal nature.

(2) A pen or pencil stroke (emulated also in software).

(3) A stroke, touch, or strain, as of some quality (now rare).

(4) In biology (and later picked up in psychology), a genetically determined characteristic or condition which is some cases may be influenced by environmental factors.

(5) In programming, languages, those methods which can be used to instance or extend functionality to a class by using the class’s own interface.

1470–1480: From the French trait (line, stroke, feature, tract), from the Middle French trait (line, feature), from the Old French trait (a pulling (literally “something drawn”)), from the Latin tractus (drawing, drawing out, dragging, pulling (an later “line drawn; feature”), from trahō, from the past participle stem of trahere (to drag, pull, draw), ultimately from the primitive Indo-European treg- (to drag, pull) which may have been a variation of dreg (to pull, draw, drag”).  In the late fifteenth century the word was used in the sense of “shot, missiles; a projectile” while the meaning “a stroke in drawing, a short line” emerged in the 1580s, that form still in technical use in graphic art and some image editing software.  The earliest known record of trait being used in English to men “a particular feature or distinguishing quality” dates from 1752.  Like niche, the tradition pronunciation (trey) is now so rare that its use might be counter-productive because it likely only to mislead and the form treyt, once known only in North America, seems now universal.  Such an evolution should not be resisted because English has always worked this way although there will be snobs who cherish trey as a class-identifier however wrong-headed this may be.  Trait is a noun and trait-like is an adjective; the noun plural is traits.

In the biological sciences, a trait refers to any observable characteristic of an organism and that might be physical, physiological, or behavioral and can be something the result entirely of genetic inheritance or a combination of genetic and environmental factors.  Like niche (another word where the US pronunciation seems to have prevailed), trait was borrowed from biology by psychology where it describes enduring patterns of thought, feelings or behavior which tend to be relatively stable despite the influence of external factors but traits in psychology are acknowledged often to be affected by both genetic and environmental factors.  Crucially, the understanding in human psychology notes the significance of the relationship in trait development between external factors and an individual’s reaction to them.  For psychologists, the study of traits often focuses on individual differences and how they contribute to personality and behavior whereas in botany & zoology etc, it’s usually more about what can be generalized about species & sub-species.

The personality traits of some attract much attention.

So, while the essential concept of traits is common between biology and psychology, the focus and application differ. In biology, traits are studied to understand the characteristics of organisms and how they evolve while in psychology traits are studied to understand human personality and behavior.  In general use (and that includes pop-psychology), the word (often in the form “character trait”) is used as a synonym for characteristic, peculiarity, mark, attribute, property etc and is well-understood, nobody confusing a genetic trait (like hair color) with descriptions of behavioral proclivities.  The apparently strange use in computer programming does make sense even though it can be argued that in programming languages there’s really no such thing as genetics (except in the abstract although the simile is useful in things like the change-logs which document changes from version-to-version) and everything is environmental.  However, the idea does work because what it means is that aspects of the language which manifest as particular characteristics of the type will appear also in the function of the software produced, something most apparent when a functional change is obvious such as when object-oriented programming (OOP, which was an example of when the over-used term “paradigm change” was justified) began to become dominant in consumer-level application in the 1990s.

The Personality Inventory for DSM-5 (PID-5) is a 220 item self-rated personality trait assessment scale for adults.  The domains appear in the middle column, with contributed facets (green, left) and non-contributed facets (blue, right).

The notion of personality traits of course underlie much of the content of the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM) and the most notable codification of the approach to personality disorders appeared in the DSM-5 (2013).  Although there have been detail changes in the DSM-5-TR (2022), the structure has been maintained and the revisions were most concerned with ensuring the diagnostic criteria accommodated the not unusual situation of a patient meeting the criteria for a specific personality disorder frequently also satisfying those for other personality disorders.  The emphasis remains on personality disorders being characterized by impairments in personality functioning and pathological personality traits.  The specific personality disorder diagnoses that may be derived from this model include antisocial, avoidant, borderline, narcissistic, obsessive-compulsive, and schizotypal personality disorders but there’s also the diagnosis of “personality disorder—trait specified” (PD-TS) which can be made when a personality disorder is considered present but the criteria for a specific disorder cannot be met.