Sex differences in cognition

Cognitive abilities

Cognitive abilities are mental abilities that a person uses in everyday life, as well as specific demand tasks. The most basic of these abilities are memory, executive function, processing speed and perception, which combine to form a larger perceptual umbrella relating to different social, affective, verbal and spatial information. Memory, which is one of the primary core of cognitive abilities can be broken down into short-term memory, working memory and long-term memory. There are also other abilities relating to perceptual information such as mental rotation, spatial visualization ability, verbal fluency and reading comprehension. Other larger perceptual umbrellas include social cognition, empathy, spatial perception and verbal abilities.

Short term memory

Various researchers have conducted studies to determine the differences between men and women and their abilities within their short-term memory. For example a study conducted by Lowe, Mayfield, and Reynolds (2003) examined gender differences among children and adolescents on various short-term memory measures. This study included 1,279 children and adolescents, 637 males and 642 females, between the ages of 5 and 19. They found that females scored higher on two verbal subtests: Word Selective Reminding and Object Recall, and males scored higher on the Memory for Location and Abstract Visual Memory subtests, the key spatial memory tasks. In two different studies researchers have found that women perform higher on verbal tasks and men perform higher on spatial tasks (Voyer, Voyer, & Saint-Aubin, 2016). These findings are consistent with studies of intelligence with regards to pattern, females performing higher on certain verbal tasks and males performing higher on certain spatial tasks (Voyer, Voyer, & Saint-Aubin, 2016). A similar study by Knox, Bergstein, Seth, Longo, McElveen (n.d.) concluded that none of their male subjects were able to compete with their female subjects in the amount of questions they got correct. This suggests that females definitely have better short term memory than males. Therefore, it would seem that gender does play a role in the usage of short term memory.Another 2015 study published in the Journal of International Neuropsychology Society also replicated the results. Same results have been also found cross culturally. Sex differences in verbal short term memory have been found regardless of age even among adults, for example a review published in the journal Neuropsychologia which evaluated studies from 1990–2013 found greater female verbal memory from ages 11–89 years old.

Working memory

There are usually no sex differences in overall working memory except those involving spatial information such as space and object. A 2004 study published in the journal of Applied Cognitive Psychology found significantly higher male performance on four visuo-spatial working memory. Another 2010 study published in the journal Brain and Cognition found a male advantage in spatial and object working memory on an n-back test but not for verbal working memory. Similarly another study published in the journal Human Brain Mapping found no sex differences in a verbal n-back working memory task among adults from ages 18–58 years old. There was also no sex differences in verbal working memory among a study of university students published in the Journal of Dental and Medical Sciences. However, they still found greater male spatial working memory in studies published in the journals Brain Cognition and Intelligence. Also, even though they found no sex differences in verbal working memory, researchers have found lower brain activity or hermodynamics in the prefrontal cortex of women which suggested greater neural efficiency and less effort for the same performance. Researchers indicate women might have greater working memory on tasks that only relies on the prefrontal cortex. A 2013 study published in the journal Current Research in Psychology also found a female advantage in one visual-working memory task among university students. A 2006 review and study on working memory published in the journal European Journal of Cognitive Psychology also found no gender differences in working memory processes except in a double-span task where women outperformed men. There have also been no sex differences found in a popular working memory task known as n-back among a large number of studies.

Long term memory

Studies have found a greater female ability in episodic memory involving verbal or both verbal and visual-spatial tasks while a higher male ability that only involves complex visual-spatial episodic memory. For example, a study published in the journal Neuropsychology found that women perform at a higher level on most verbal episodic tasks and tasks involving some or little visual-spatial episodic memory. Another study published the following year found that women perform at a higher level in verbal and non-verbal (non-spatial visual) episodic memory but men formed at a higher level in complex visual-spatial episodic memory. A review published in the journal Current Directions in Psychological Science by researcher Agneta Herlitz also conclude that higher ability in women on episodic-memory tasks requiring both verbal and visuospatial episodic memory and on face-recognition tasks.

Sex differences in semantic memory have also been found with a higher female ability which can be explained by a female advantage in verbal fluency. One other study also found greater female free-recall and long term retrieval among the ages 5–17.

Sex differences in executive functions

There has not been enough literature or studies assessing sex difference in executive functioning, especially since executive functions are not a unitary concept. However, in the ones that have been done, there have been differences found in attention and inhibition.

Attention

A 2002 study published in the Journal of Vision found that males were faster at shifting attention from one object to another as well as shifting attention within objects. 2012–2014 studies published in the Journal of Neuropsychology with a sample size ranging from 3500–9138 participants by researcher Ruben C Gur found higher female attention accuracy in a neurocognitive battery assessing individuals from ages 8–21. A 2013 study published in the Chinese Medical Journal found no sex differences in executive and alerting of attention networks but faster orientation of attention among females. A 2010 study published in Neuropsychologia also found greater female responsiveness in attention to processing overall sensory stimulation.

Inhibition and self-regulation

A 2008 study published in the journal Psychophysiology found faster reaction time to deviant stimuli in women. The study also analyzed past literature and found higher female performance in withholding social behavior such as aggressive responses and improper sexual arousal. Furthermore, they found evidence that women were better at resisting temptation in tasks, delaying gratification and controlling emotional expressions. They also found lower female effort in response inhibition in equal performance for the same tasks implying an advantage for females in response inhibition based on neural efficiency. In another study published in 2011 in the journal Brain and Cognition, it was found that females outperformed males on the Sustained Attention to Response Task which is a test that measures inhibitory control. Researchers have hypothesized that any female advantage in inhibition or self-regulation may have evolved as a response to greater parenting responsibilities in ancestral settings.

Sex differences in processing speed

Sex differences in processing speed has been largely noted in literature. Studies published in the journal Intelligence have found faster processing speed in women. For example, a 2006 study published in Intelligence by researcher Stephen Camarata and Richard Woodcock found faster processing speed in females across all age groups in a sample of 4,213 participants. This was followed by another study published in 2008 by researchers Timothy Z Keith and Matthew R. Reynolds who found faster processing speed in females from ages 6 to 89 years old. The sample also had a number of 8,818 participants. Other studies by Keith have also found faster processing speed in females from ages 5 to 17.

Sex differences in semantic perception

Studies of sex differences in semantic perception (attribution of meaning) of words reported that males conceptualize items in terms of physical or observable attributes whereas females use more evaluative concepts. Another study of young adults in three cultures showed significant sex differences in semantic perception (attribution of meaning) of most common and abstract words. Contrary to common beliefs, women gave more negative scores to the concepts describing sensational objects, social and physical attractors but more positive estimations to work- and reality-related words, in comparison to men This suggests that men favour concepts related to extreme experience and women favour concepts related to predictable and controllable routines. In a light of the higher rates of sensation seeking and deviancy in males, in comparison to females, these sex differences in meaning attribution were interpreted as support for the Evolutionary theory of sex.

Sex differences in spatial abilities

Sex differences in spatial abilities are widely established in literature. Males have much higher level of performance in three major spatial tasks which include spatial visualization, spatial perception and mental rotation. Spatial visualization illicit the smallest difference with a deviation of 0.13, perception a deviation of 0.44 and mental rotation the largest with a deviation of 0.73. Another 2013 meta-analysis published in the journal Educational Review found greater male mental rotation in a deviation of 0.57 which only grew larger as time limits were added. These male advantages manifests themselves in math and mechanical tasks for example significantly higher male performance on tests of geometry, measurement, probability, statistics and especially mechanical reasoning. It also manifests and largely mediates higher male performance in arithmetic and computational fluency All of these math and technical fields involve spatial abilities such as rotation and manipulation of imagined space, symbols and objects. Mental rotation has also been linked to higher success in fields of engineering, physics and chemistry regardless of gender. Spatial visualization on the other hand also correlate with higher math achievement in a range of 0.30 to 0.60. Furthermore, male advantage in spatial abilities can be accounted for by their greater ability in spatial working memory. Sex differences in mental rotation also reaches almost a single deviation (1.0) when the tasks require navigation, as found in one study with participants who used Oculus Rift in a virtual environment.

Even though most spatial abilities are higher in men, object location memory or the ability to memorize spatial cues involving categorical relations are higher in women. Higher female ability in visual recognition of objects and shapes have also been found.

Sex differences in verbal abilities

Like spatial ability, sex differences in verbal abilities have been widely established in literature. There is a clear higher female performance on a number of verbal tasks prominently a higher level of performance in speech production which reaches a deviation of 0.33 and also a higher performance in writing Studies have also found greater female performance in phonological processing, identifying alphabetical sequences, and word fluency tasks. Studies have also females outperforming males in verbal learning especially on tests such as Rey Auditory Verbal Learning Test and Verbal Paired Associates. and A 2010 study published in the Journal of Advanced Prosthodentics found women showed significantly higher speech intelligibility scores than men and differences in acoustic (sound) parameters. Meanwhile, in another studies, a female advantage in generating synonyms and solving anagrams have also been found. Furthermore, a 2009 study published in the Archive of Clinical Neuropsychology found better female performance in writing that reached about 8 points in a sample of 22–80 year old adults, in relation to better male performance in math which reached about 4 points. It has also been found that the hormone estrogen increases ability of speech production and phonological processing in women, which could be tied to their advantages in these areas. Overall better female performance have also been found in verbal fluency which include a trivial advantage in vocabulary and reading comprehension while a significantly higher performance in speech production and essay writing. This manifests in higher female international PISA scores in reading and higher female Grade 12 scores in national reading, writing and study skills. Researchers Joseph M. Andreano and Larry Cahill have also found that the female verbal advantage extends into numerous tasks, including tests of spatial and autobiographical abilities. Another 2008 study published in the journal Act Psychologica found no sex differences in remembering phonologically-unfamiliar novel words but higher female ability to remember phonologically-familiar novel words. Meanwhile, higher depth of processing in semantic analysis among females compared to males have also been found in brain imaging studies, while greater female performance in many verbal abilities might be linked to their higher verbal memory. A 2013 study published in the International Journal of Psychology also found an adult female advantage in time for performing a verbal lexical task and temperament scale of social-verbal tempo.

Sex differences in social cognition

Current literature suggests women have higher level of social cognition. A 2012 review published in the journal Neuropsychologia found that women are better at recognizing facial effects, expression processing and emotions in general. Men were only better at recognizing specific behaviour which includes anger, aggression and threatening cues. A 2012 study published in the journal Neuropsychology with a sample of 3,500 individuals from ages 8–21, found that females outperformed males on face memory and all social cognition tests. In 2014, another study published in the journal Cerebral Cortex found that females had larger activity in the right temporal cortex, an essential core of the social brain connected to perception and understanding the social behaviour of others such as intentions, emotions, and expectations. In 2014, a meta-analysis of 215 study sample by researcher A.E. Johnson and D Voyeur in the journal Cognition and Emotion found overall female advantage in emotional recognition. Other studies have also indicated greater female superiority to discriminate vocal and facial expression regardless of valence, and also being able to accurately process emotional speech. Studies have also found males to be slower in making social judgments than females. Structural studies with MRI neuroimaging has also shown that women have bigger regional grey matter volumes in a number of regions related to social information processing including the Inferior frontal cortex and bigger cortical folding in the Inferior frontal cortex and parietal cortex Researchers have indicated that these sex differences in social cognition predisposes males to high rates of autism spectrum disorders which is characterized by lower social cognition.

Empathy

Empathy is a large part of social cognition and facilitates its cognitive components known as theory of mind. Current literature suggests a consistent higher level of empathy in woman compared to men. A 2006 meta-analysis by researcher Rena A Kirkland in the journal North American Journal of Psychology found significant sex differences favoring females in the "Reading of the mind" test. The "Reading of the mind" test is an advanced ability measure of cognitive empathy in which Kirkland's analysis involved 259 studies across 10 countries. Another 2014 meta-analysis in the journal Cognition and Emotion, found overall female advantage in non-verbal emotional recognition across 215 samples.

Using fMRI, neuroscientist Tania Singer showed that empathy-related neural responses are significantly lower in males when observing an "unfair" person experiencing pain. A 2014 study by researchers Chiyoko Kobayashi Frank, Simon Baron-Cohen and Barbara L. Ganzel found that on average women use brain networks correlated with both cognitive empathy (more activation in the mPFC) and affective empathy (deactivation in the vmPFC) more than men, and this can partly explain for women's better performance in theory of mind or cognitive empathy skills. An 2014 analysis from the journal Neuroscience & Biobehavioral Reviews also found that there are sex differences in empathy from birth, growing larger with age and which remains consistent and stable across lifespan. Females were found to have higher empathy than males, while children with higher empathy regardless of gender continue to be higher in empathy throughout development. Further analysis of brain tools such as event related potentials found that females who saw human suffering had higher ERP waveforms than males. Another investigation with similar brain tools such as N400 amplitudes found higher N400 in females in response to social situations which positively correlated with self-reported empathy. Structural fMRI studies also found females to have larger grey matter volumes in posterior inferior frontal and anterior inferior parietal cortex areas which are correlated with mirror neurons in fMRI literature. Females were also found to have stronger link between emotional and cognitive empathy. The researchers found that the stability of these sex differences in development are unlikely to be explained by any environment influences but rather might have some roots in human evolution and inheritance.

Throughout prehistory, females nurtured and were the primary caretakers of children, so this might have led to an evolved neurological adaptation for women to be more aware and responsive to non-verbal expressions. According to the Primary Caretaker Hypothesis, prehistoric males did not have the same selective pressure as primary caretakers; so therefore this might explain modern day sex differences in emotion recognition and empathy.