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