Effects of Gender and Luminance Backgrounds on the Recognition of Neutral Facial Expressions

Abstract

In this study we challenged the universal view of facial emotion perception evaluating the effects of gender and different luminance backgrounds on the recognition accuracy of neutral facial expressions. To this aim, we applied the Ekman standard paradigm for assessing the human ability to decode neutral facial expressions reproduced on black, white and grey backgrounds and portrayed by male and female actors. The exploited stimuli consisted of 10 different neutral faces (5 females) selected from the Dutch Radboud database (Langner et al. Cogn Emot, 2010 [21]) where luminance backgrounds were changed in black, grey and white. The resulted 30 stimuli were assessed by 31 subjects (16 females) who were asked to tag each of them with one of the six primary emotion labels. The data analysis demonstrates a significant gender effect where neutral male faces are less accurately decoded than females ones. On the other hand, no effects of luminance backgrounds have been identified.

Supplemental Material

Observer Questionnaire

Each potential observer completed the following (culture appropriate) questionnaire. We selected only participants that answered to the following questions as reported below⁴:

Please answer to the following questions

• 1. Vision

Do you have normal (uncorrected) vision, do you wear glasses or contact lenses, or are you visually impaired?–

☑ Normal vision ☑ Glasses ☑ Contact Lenses ☐ Visually Impaired

• 2. Laterality

Since the left part of the brain control the right side of the body, and the right part of the brain controls the left side, it is important to know such things as handedness of subjects before running an experiment. Are you left, right-handed or ambidextrous (use both hands equally)?

☐ Left-handed ☑ Right-handed ☐ Ambidextrous

• 3. Learning disabilities

The term learning disability is used to refer to individuals who show a discrepancy between their apparent capacity to learn and their level of achievement. Specific learning disabilities include difficulties with:

• reading (dyslexia)

• writing (dysgraphia)

• speech and language (dysphasia or aphasia)

• maths (dyscalcula)

• motor-planning (dyspraxia)

A learning disability can also be a difficulty with information processing, such as visual and auditory perception (e.g. difficulty recognizing shapes). If you are aware of any learning disability that you may have please specify this here. Do you suffer from learning disability?

☐ Yes ☑ No

• 4. Synaesthesia

Synaesthetes experience a fascinating phenomenon called synaesthesia, a “joining together” of two senses that are normally experienced separately. There are many, many types of synaesthesia. For example, synaesthetes may perceive colours when they read numbers, letters, or words; the colours may be superimposed on the graphemes themselves or merely perceived in their “mind’s eye”. Synaesthetes may “hear colours”, “see sounds”, or feel touch sensations on their own bodies when they observe others being touched. Likewise, the days of the week or even numbers may appear in a specific location, form, or shape.

Take a look at the following questions and statements. If your answer to any of them is either “yes” or “sometimes”, then you may be a synaesthete.

• I experience colours when I look at written numbers.

• I experience colours when I look at written letters.

• I experience colours when I look at written words.

• Each number/letter/word has a specific colour.

• I associate numbers to colours.

• I associate letters to colours.

• I associate words to colours.

• I experience touch on my own body when I look at someone else being touched (i.e., I feel touch sensations on my own body when I observe them on another person’s body).

• I experience touch on my own body when I look at something else being touched (i.e., I feel touch sensations on my own body when I observe them on objects).

• I experience touch in response to body postures.

• Do these experiences have specific locations (i.e., on your body, on words or objects, in front of your eyes) or not (i.e., you just “know” or they feel as though they are in your “mind’s eye”)?

• Do you think about ANY of the following being arranged in a specific pattern in space (i.e., in a line, a circle, etc.)? ALPHABET, CALENDAR YEAR, DAYS OF THE WEEK, WEEKS, TIME, NUMBERS (NUMBER LINE)

• Do you think about numbers/letters/words as having personalities or genders?

• Do you experience colours in response to: SOUNDS, MUSIC, VOICES, TOUCH. If your answer to any of those questions is YES or SOMETIMES, you may be a synaesthete.

Are you a synaesthete? ☐ Yes ☑ No

• 5. Hearing

Do you have normal hearing, corrected hearing (e.g. cochlear implant) or is your hearing impaired (e.g. tinnitus)?

☑ Normal ☐ Corrected ☐ Impaired