Mental images are unique mental representations and the depictive view in the imagery debate states that mental images have similar spatial structures as their corresponding external object. The propositional view, however, contends that beliefs about the external world influence a mental image – also known as the cognitive penetrability theory –, therefore mental images cannot be described in visual terms. People with self-described aphantasia, those considered lacking visual mental images, offer a new opportunity to approach this issue. The current study employed the mental rotation task (MRT), where a three-dimensional object needs to be mentally aligned with another one that is rotated to a different angular position. To test the effects of beliefs on mental images, different instruction conditions were used on the MRT. Twenty-seven participants (21 females, mean age 47 years) with self-described aphantasia completed an online experiment, consisting of the MRT, the Object-Spatial Imagery Questionnaire (OSIQ), and the Vividness of Visual Imagery Questionnaire (VVIQ). While participants scored low on the VVIQ and higher on the spatial items than on the object items of the OSIQ, the key finding was that increasing reaction time with increasing angular disparity on the MRT was not influenced by different instruction types. This suggests that the theory of cognitive penetrability is not applicable on mental rotation in aphantasia, highlighting the importance to revise how mental images (or the lack of them) are understood and described.

While previous research on episodic memory vividness aims at measuring episodic memory, such cognitive tasks also involve visual mental imagery since vividness is primarily a property of visual mental imagery. Literature also shows that subjective measurements of visual mental imagery (e.g., the Vividness of Visual Imagery Questionnaire; VVIQ) are confounded by demand characteristic effects, either by participant response biases or instructional cues. Investigating such claims is most suitable in those who report an absence of visual mental imagery, that is, in aphantasia. Therefore, this study examines whether subjective vividness ratings are interpreted differently between a “visualize” and a “recollect” version of the VVIQ. One hundred and thirty-nine participants filled out online either one of the versions of the questionnaire, which also included an additional manipulation on demand characteristics (i.e., instructional cues on what alleged previous research found on response patterns). Eighty-nine participants self-described with aphantasia. Results showed that irrespective of self-describing with aphantasia or not, participants scored comparably on the two versions of the questionnaire (with aphantasic participants scoring overall lower than control participants), favouring the interpretation that episodic memory vividness involves visual mental imagery. Furthermore, no demand characteristic effects were found in those self-describing with aphantasia, whereas controls’ questionnaire scores were affected only negatively by the employed instructional cues. Different interpretations of such results are discussed, highlighting the idea that it is a difficult methodological exercise to discern the two theoretical constructs: visual mental imagery and episodic memory.

O debate da imagética mental consiste de uma controvérsia iniciada nos anos 1970 a respeito da forma das representações mentais, e foi travada principalmente entre Stephen Kosslyn, que propunha uma forma imagética, e Zenon Pylyshyn, que propunha um formato simbólico-estrutural, além de apontar falhas conceituais na teoria da afiguração implícita no modelo pictorialista. Nesta dissertação, apresenta-se um balanço filosófico deste debate, levando em conta também críticas adicionais de Daniel Dennett aos pressupostos da abordagem pictorialista. / The mental imagery debate is a controversy that began in the 1970s concerning the form of mental representation, and was carried out mainly by Stephen Kosslyn, who defended a picture-like representation, and Zenon Pylyshyn, who proposed a symbolic-structural format. The latter also pointed out conceptual problems of the pictorialist model. This thesis presents a philosophical discussion of the debate, also taking into account additional criticisms by Daniel Dennett to the presuppositions of the pictorialist approach.

O debate da imagética mental consiste de uma controvérsia iniciada nos anos 1970 a respeito da forma das representações mentais, e foi travada principalmente entre Stephen Kosslyn, que propunha uma forma imagética, e Zenon Pylyshyn, que propunha um formato simbólico-estrutural, além de apontar falhas conceituais na teoria da afiguração implícita no modelo pictorialista. Nesta dissertação, apresenta-se um balanço filosófico deste debate, levando em conta também críticas adicionais de Daniel Dennett aos pressupostos da abordagem pictorialista. / The mental imagery debate is a controversy that began in the 1970s concerning the form of mental representation, and was carried out mainly by Stephen Kosslyn, who defended a picture-like representation, and Zenon Pylyshyn, who proposed a symbolic-structural format. The latter also pointed out conceptual problems of the pictorialist model. This thesis presents a philosophical discussion of the debate, also taking into account additional criticisms by Daniel Dennett to the presuppositions of the pictorialist approach.