I've heard that red clothing is forbidden for women to wear because it's immodest. Some recent psych research confirmed that men are more attracted to women in red. So that means it's prohibited, right?
There are traditional sources (e.g. the Talmud discusses shoelaces) that yes, red is flashier and perhaps more attractive. That doesn't mean it's prohibited.
If you look up "red clothing" in the index to the Igrot Moshe, you'll find the following discussion by Rabbi Moshe Feinstein:
A style of clothing can be prohibited if it's just plain inappropriate. Another way a style of clothing can be prohibited is if this is a "non-Jewish" style, i.e. Jewish women have abstained from wearing it until now, AND this style is somewhat flashier, for instance it's red.
Writing in 1953, Rabbi Feinstein feels that the latter point is moot, as he is not aware of any clearly "non-Jewish" clothing styles in America; most American clothing (provided it's appropriate) is also "American Jewish" clothing.
In "Contemporary Tzniut", Rabbi Yehuda Herzl Henkin argues that just because clothing is attractive doesn't make it prohibited. See Rashi's commentary on Genesis 49:11: “And colorful clothing” is expressed by the word סוּתֹה, [a garment] a woman wears to entice [מְסִיתָה] a male to cast his eyes on her." This description appears as part of a Biblical blessing, and we don't see it prohibited.
I recall reading the study in question and it is significant in that the color red did not effect how the male perceived the female's other traits such as intelligence or kindness but only his, shall we say, interest in her. Although it is not clear based on this study whether this tendency is the result of biological factors, cultural factors, or both, it strongly suggests that the color red does have a certain effect even in contemporary society which may not be particularly welcome from the standpoint of tznius (modesty).
While others have noted that there are authorities who are lenient with respect to wearing the color red, it should be recognized that the Rema in Yoreh Dea 178:1 writes that: "Rather one should be distinct [from non-Jews] in his dress and in his other ways, but all of this isn't prohibited unless it is done by non-Jews for reasons of immodesty, for example they are accustomed to wearing red clothes" To this the Sifsei Cohen (Shach 178:3) adds, "since it is not the way of the modest to have red in their clothes" (transl. mine, sorry for any imperfection).
Rav Moshe Feinstein zt'l (Igros Moshe Y.D. 1:81) rules that red clothing do not constitute a transgression of the prohibition against chukkas hagoy (non-Jewish customs) in contemporary society but describes them as having a tinge of immodesty (pritzus) and there is no explicit (nor I believe implicit) licence given to wear them. Indeed he explicitly states that the among the clothing he mentioned as not being prohibited due to chukkas hagoy there are those which are prohibited do to immodesty. Insofar as he closes with the statement that such a consideration (immodesty without the problem of non-Jewish clothing) is not relevant to men, it would seem that red clothing would be at the forefront of types of "immodest" clothing he referred to (i.e. those conceivably worn by men).
According to Rav Wosner shlita the prohibition against wearing red is still applicable, and that one is obligated to educate older children to abstain from wearing red clothing ( Shevet HaLevi 6:24:2). According to Rav Elyashiv shlita this prohibition is also in effect, albeit only with respect to bright red (I don't believe that there is a disagreement about this, nor that there are other colors which the prohibition does apply to). The Be'er Moshe 4:147:13 also applies the prohibition to contemporary times. It is related in the name of Rav Yaakov Kaminetzky zt’l that it is permitted to wear red but it is preferable not to.
It would seem that according to Rav Shlomo Zalman Aurbach zt"l that red is prohibited, but that it is permitted when it is an incidental accent to the garment.
Since we see that, in fact, there appears even in contemporary times a statistically significance increase in less-than-modest association with the color red I'm inclined to believe one should not be quick to dismiss the explicit words of these (and other) Gedolei haPoskim. I would add, however, that while the study may not have revealed any similar perception by women viewing men in red (though I don't believe it addressed that question)
The discussion above re: prohibition due to the ways of the non-Jews is one issue. However, "Tzenius" is not just about legal prohibitions. It is a "Midda Tova" and it is a lauded character trait among Jews. It was described by Bila'am in his praise for Israel, and Rashi mentions it as a "worthy practice" a few places (e.g. Sanhedrin end of seventh chapter), not rising to the level of a full Mitzva, but nevertheless a mitzva. The Sma"k (57) considers it a full mitzva. A verse in Tenach (Micha 6) is one of the sources for this as well:
Tzenius in this sense is the practice of not calling attention to oneself, but rather operating discreetly, and it applies to man and woman alike. For a woman, wearing red, or skirts with slits, or anything that draws a man's attention, would not be considered "tzniusdik" by this definition.
on a mystical level not only women but anyone is not not reccomended to wear red, it means dinim
If a clothe has only a little red on it is Mutar according to everyone and also a clothe which isn't really red like pink is Mutar. And nowadys there a Posekim that are Matir to wear and those who are Mekil have upon whom to rely.
Just adding some Talmudic sources around which most of this debate centers. In Berachot 20a, when discussing the amazing levels of self-sacrifice to be found in generations previous to them, the Gemara relates, "Rav Ada bar Ahava saw this non-Jewess that was wearing a carbalata in the market. He thought that she was a Daughter of Israel, [so] he arose and tore it from her. It became revealed that she was a non-Jewess, and they assessed [his requirement to compensate] it at 400 zuz. He said to her, 'What is your name?' She said to him, "Matun!" He said to her, 'Matun? Matun is worth 400 zuz!'" (Rashi explains this final pun in 2 ways. Either he's referring to Ma'atan, Aramaic for the number 200, so he's saying "Ma'atan plus Ma'atan is worth 400 zuz!" Alternately, he's referring to metinut, the patient investigation he had not done, so he's saying "Patience? Learning patience is worth 400 zuz!")
Carbalata is the same word used for a rooster's comb. Rashi translates it in context as "the name of an expensive garment". The Aruch in his dictionary says, "A red article of clothes, like the comb of a rooster, for it is not the normal way of Daughters of Israel to clothe themselves with it, for it is pritzut (immodesty) and leads to sinful acts." (Pritzut has a connotation of poretz geder, breaking through societal mores - hence, immodesty.)
So, carbalata is either an article of clothes that's red as a rooster's comb (Aruch), or one that helps you strut like a rooster (Rashi)...
At the very bottom of Sanhedrin 74a, the Talmud discusses the requirement to give your life in sanctification of G-d's Name. It states that if a) it is a time of anti-Judaic governmental decrees, or b) if it's a public demand to capitulate, "even on a mitzva kala ("light" mitzvah), one should allow himself to be killed rather than transgress. The Talmud then asks "What is a mitzva kala?", to which it responds on the top of 74b, "Even to change the laces of sandals!"
Rashi explains, "...if it is the way of the idol worshipers to tie the laces so, and the way of Jews in a different way - for example, when there is a Judaic aspect to it, and it is the way of Israel to be modest people - even this change, when there is no mitzva but just a general custom, he should sanctify The Name before his Jewish peers..." Nothing about red, but a general mention of modesty. In Tosafot, Rabbeinu Tam opines that Jews wore white shoelaces while all others wore black. Again, no red. However, many other Rishonim & Acharonim do specifically reference red (see Hagahot Maimoniyot on Yesodei HaTorah 5:2).
For example, Kitzur Shulchan Aruch (Code of Jewish Law, Ganzfried) says in 3:2, "We don't walk in the statutes of the idol worshippers, nor do we imitate them, not in dress nor in hairstyles and similar things... He should not wear clothing that is specific to them for haughtiness... As an example, this that the Talmud says (San. 74b) that it is prohibited for a Jew to imitate them even with shoelaces, for it was their way to tie like so & the way of Israel in a different way, OR (capitalization mine, RR) that their custom was to have red laces and those of Jews were black, for the color black demonstrates humility and humbleness and modesty, [so] it is prohibited for a Jew to change. And from this each person should learn, ACCORDING TO HIS TIME AND PLACE..."
So, KSA hedged his bets: He mentioned Rashi's "it was their way to tie like so", other Rishonim's red vs. black (which sounds like the effects of red & black are an OBJECTIVE reality), then says that it depends on the time and place (which sounds like immodesty is SUBJECTIVE). Left open is our question: Is red objective while many (most?) other forms of immodesty are subjective, or are they ALL subjective?
Do colors still affect us? This study says it does, though we don't know how the results would change if these colors were worn by the other person rather than painted on the wall.
Parenthetically, an ex-TSA agent just admitted that they had special codes for attractive female passengers, with red & yellow clothes getting special mention. Just sayin'...