Is our inner voice our conscience?

I say to myself…

There­fore I am ?

Lan­guage allows us to com­mu­ni­cate our thoughts, emo­tions, and feel­ings to oth­ers – its com­mu­nica­tive func­tion is essen­tial. We speak with oth­ers, but we also speak to our­selves, inter­nal­ly, to think. Hence, lan­guage also has a cog­ni­tive func­tion, as Egypt­ian schol­ars, and Greek philoso­phers from Her­a­cli­tus to Aris­to­tle, via Pla­to, already knew. Lat­er, Descartes, in the Dis­course on Method¹ revealed a third essen­tial func­tion of lan­guage – metacog­ni­tive – where­by the think­ing sub­ject is aware of itself: “I think, there­fore I am”, as he wrote.

Lan­guage has indeed a cru­cial role in self-aware­ness, which can be defined as the recog­ni­tion of one’s own exis­tence. But the Carte­sian notion of the self as a sta­ble and uni­fied sub­stance has been ques­tioned, as the self is depen­dent on sit­u­a­tions – it is in per­pet­u­al motion. Con­tem­po­rary reflec­tions in phi­los­o­phy, lin­guis­tics and cog­ni­tive sci­ences have made it pos­si­ble to put for­ward new ele­ments of response to this ques­tion of self-aware­ness. We can con­sid­er that it is built up through lan­guage, start­ing from a so-called “min­i­mal” or prim­i­tive self-con­scious­ness, shared with cer­tain non-human ani­mals². The elab­o­rate self-con­scious­ness, and the men­tal posi­tion­ing in time, called auto­noet­ic con­scious­ness, is based on lan­guage and seems to be spe­cif­ic to human beings.

Min­i­mal self-aware­ness, con­sist­ing of pure per­cep­tu­al expe­ri­ences, with­out lan­guage, seems to exist in infants. Visu­al per­cep­tion and somat­ic pro­pri­o­cep­tion makes it pos­si­ble to asso­ciate the feel­ing of move­ment of one’s body with the obser­va­tion of one’s body in motion. In infants, it con­tributes to the expe­ri­ence of a dif­fer­en­ti­at­ed self, sit­u­at­ed in space, with a bound­ed body.

Elab­o­rate self-aware­ness is scaf­fold­ed on min­i­mal self- aware­ness and brings lex­i­cal and syn­tac­tic tools into play. The acqui­si­tion of pro­nouns by chil­dren, around the age of two, enables them to dif­fer­en­ti­ate between “I” and “you” or “mine” and “yours”. It indi­cates the con­scious emer­gence of the con­trast between the self and the oth­er. Then, with the increase in vocab­u­lary, demon­stra­tives, adverbs, and the use of verb tense, which all organ­ise spa­tial and tem­po­ral rela­tions, with the self as the ori­gin (“this, here, now, yes­ter­day, tomor­row”), chil­dren can bet­ter rep­re­sent them­selves and oth­ers. In this way, they can con­struct nar­ra­tives about past mem­o­ries and future intentions.

Through­out life, thanks to lan­guage, human beings cre­ate an iden­ti­ty, or rather an ipse­ity, a sense of “self” expand­ed over time. Thus, while lan­guage obvi­ous­ly enables inter-human com­mu­ni­ca­tion, its major role in thought and in auto­noet­ic con­scious­ness has favoured its inter­nal­i­sa­tion. By inhibit­ing the pro­duc­tion of overt lan­guage, by inter­nal­ly sim­u­lat­ing lan­guage, human beings can secret­ly devel­op their self-awareness.

As we have shown at the Lab­o­ra­toire de Psy­cholo­gie et Neu­roCog­ni­tion in Greno­ble, in an fMRI neu­roimag­ing study, dur­ing the pro­duc­tion of inner speech, the brain regions of overt speech are acti­vat­ed, as well as regions of the pre­frontal cor­tex, involved in inhi­bi­tion⁴. The pos­si­bil­i­ty of inhibit­ing and speak­ing inter­nal­ly to one­self, what Georges Saint-Paul called in 1892 “endopha­sia”⁵, thus seems fun­da­men­tal. By talk­ing to our­selves to recall mem­o­ries, plan things, imag­ine oth­ers, or even to engage in self-cri­tique, we can cre­ate an extend­ed sense of self-aware­ness over time.

The links between endopha­sia, or inner lan­guage, and mem­o­ry have been exten­sive­ly stud­ied by psy­cholin­guists. In par­tic­u­lar, inner lan­guage inter­acts with work­ing mem­o­ry, the short-term mem­o­ry that allows us to store and manip­u­late infor­ma­tion tem­porar­i­ly to accom­plish a task. To remem­ber a tele­phone num­ber or a code to dial, to remem­ber a shop­ping list, we can say them inter­nal­ly, in a loop. The inter­nal rep­e­ti­tion of the words to be remem­bered allows the infor­ma­tion to be tem­porar­i­ly held in mem­o­ry. This type of work­ing mem­o­ry is based on the sound of words. This can be ver­i­fied with an exper­i­ment that has been repli­cat­ed many times, in which par­tic­i­pants are asked to remem­ber a list of words⁶.

For exam­ple:

camp, foot, nail, floor, wall

Or :

bat, mat, hat, pat, cat

Words that are pro­nounced the same are like­ly to be con­fused, result­ing in poor­er recall of the sec­ond list than the first. This is known as the phono­log­i­cal sim­i­lar­i­ty effect, an effect that reveals that par­tic­i­pants use inner rep­e­ti­tion of words to retain them.

Auto­bi­o­graph­i­cal mem­o­ry can also be enhanced by endopha­sia. One can evoke mem­o­ries, recall a past event, by talk­ing to one­self inter­nal­ly. Auto­bi­o­graph­i­cal mem­o­ry is based on nar­ra­tive con­struc­tions that allow events to be organ­ised coher­ent­ly in time, and to be inscribed in a per­son­al his­to­ry. Research on the devel­op­ment of mem­o­ry in chil­dren indi­cates that in the first two years of life, auto­bi­o­graph­i­cal mem­o­ries are vir­tu­al­ly absent. It has been sug­gest­ed that lan­guage devel­op­ment that would lat­er allow the struc­tur­ing of self knowl­edge and the cre­ation of auto­bi­o­graph­i­cal mem­o­ries organ­ised in time.

When do chil­dren start talk­ing in their head? For the psy­chol­o­gist Vygot­s­ki⁷, inner speech is inher­it­ed from overt speech, via a grad­ual process of inter­nal­i­sa­tion that takes place dur­ing child­hood. Like Piaget before him, Vygot­s­ki observed that chil­dren begin by speak­ing aloud to them­selves. In this phase, which Vygot­s­ki called ‘pri­vate speech’, the child plays alone and repro­duces dia­logue sit­u­a­tions. Then, lit­tle by lit­tle, the child learns to inhib­it this behav­iour and inter­nalis­es it. Their pri­vate speech becomes their inter­nal lan­guage between the ages of five and seven.

Recent exper­i­men­tal psy­chol­o­gy stud­ies con­firm the hypoth­e­sis that the child can speak inter­nal­ly from this age. A clas­sic exper­i­ment uses the Tow­er of Hanoi game. If, while per­form­ing the task, chil­dren are pre­vent­ed from talk­ing to them­selves in their head, by hav­ing them repeat aloud “ba ba ba”, it is observed that their per­for­mance decreas­es. This sug­gests that the child uses inner speech for action plan­ning, as ear­ly as about five years⁸. It is more dif­fi­cult to know whether inner speech is used by chil­dren in such tasks at ear­li­er ages, as their reduced per­for­mance may sim­ply be relat­ed to dif­fi­cul­ties in con­cen­tra­tion or reasoning.

How­ev­er, some recent research, notably that led by Sharon Peperkamp in Paris⁹sug­gests that infants may be able to inter­nal­ly evoke the sound of cer­tain words as ear­ly as 20 months, before they are able to artic­u­late them aloud. The researchers from the Paris team pre­sent­ed 20-month-old infants with images of objects or ani­mals, fol­lowed by a voice nam­ing the image. They used both short (such as “cat”) and long (such as “banana”) words. After the pic­ture and sound were pre­sent­ed, the child saw two emp­ty box­es on the screen. Then the pic­ture filled in one of the box­es: the left box for short words and the right box for long words. This step was repeat­ed sev­er­al times until the infant under­stood the implic­it rule: short words on the left, long words on the right. After this famil­iari­sa­tion stage, the researchers pre­sent­ed a pic­ture with­out the sound, for exam­ple a tele­phone. They observed that the infants antic­i­pat­ed and looked to the right side even before the tele­phone filled the right-hand box. This exper­i­ment sug­gests that twen­ty-month-old infants can inter­nal­ly evoke the sound of words and thus cat­e­gorise words as mono- or tri-syl­lab­ic, while they are still unable to artic­u­late them aloud.

The devel­op­ment of cer­tain forms of inner lan­guage could thus pre­cede, or even be a deter­min­ing fac­tor in, the devel­op­ment of oral lan­guage. The ques­tion remains open. Do such exper­i­ments reveal auto­mat­ic asso­ci­a­tions between an image and a mnemon­ic sound trace, or are they evi­dence for actu­al inner speech production?

Interview by Pablo Andres

For more on the topic of inner language (or endophasia):

• « Who says ‘I’ in me? », her book to be pub­lished by Denoël in May 2022: The mys­tery of inner voices
• A sci­en­tifique impromp­tu, a show cre­at­ed with the actor Mick­aël Chou­quet of the group n+1, Les ate­liers du spec­ta­cle : Des voix dans la tête (voic­es in the head)
• An ongo­ing online sur­vey on men­tal imagery and inner language